I have some troubles to get the views transitions animated when I change the UITabBarController.selectedIndex changed programmatically.
When I tap on a TabBar icon the animation works fine, but when I change the selectedIndex from a gestureRecognizer action.
The transition code at the TabBar controller class is the following:
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
if CanChangeTab {
guard let fromView = tabBarController.selectedViewController!.view, let toView = viewController.view else {
return false // Make sure you want this as false
}
if fromView != toView {
if (tabBarController.prevIndex > tabBarController.selectedIndex) {
UIView.transition(from: fromView, to: toView, duration: 0.3, options: [.transitionFlipFromLeft], completion: nil)
} else {
UIView.transition(from: fromView, to: toView, duration: 0.3, options: [.transitionFlipFromRight], completion: nil)
}
}
return true
} else {
return false
}
}
The gesture recogniser is calling the following function, from which the above code is not called:
#objc func swiped(_ gesture: UISwipeGestureRecognizer) {
if (CanChangeTab) {
self.tabBarController?.prevIndex = (self.tabBarController?.selectedIndex)!
if gesture.direction == .left {
if (self.tabBarController?.selectedIndex)! < 4 { // set your total tabs here
self.tabBarController?.selectedIndex += 1
}
} else if gesture.direction == .right {
if (self.tabBarController?.selectedIndex)! > 0 {
self.tabBarController?.selectedIndex -= 1
}
}
}
}
I cannot see what should be called or overridden to get the animations for the gesture base change too.
The problem is that what you are doing is not how to do a tab bar controller animation. You have to write a formally structured custom animation transition.
This means that:
Your tab bar controller has a delegate implementing animationControllerForTransitionFrom to return a UIViewControllerAnimatedTransitioning object, and interactionControllerFor to return a UIViewControllerInteractiveTransitioning object.
These objects implement startInteractiveTransition, interruptibleAnimator(using:), transitionDuration(using:), animateTransition(using:), and animationEnded to perform the animation through a UIViewPropertyAnimator.
The gesture recognizer will then be able to trigger the animation by setting the selectedIndex and will be able to track and update the animation through the supplied UIViewControllerContextTransitioning object and the UIViewPropertyAnimator.
Ok. I have found the solution, using ViewController slide animation
as Matt proposed.
So using the extension + the animateToTab function in the extension and changing my swipe method it works just as expected.
#objc func swiped(_ gesture: UISwipeGestureRecognizer) {
if (CanChangeTab) {
let thisTabController = self.tabBarController as! iBayTabController
thisTabController.prevIndex = (thisTabController.selectedIndex)
if gesture.direction == .left {
if thisTabController.selectedIndex < 4 { // set your total tabs here
thisTabController.animateToTab(toIndex: thisTabController.selectedIndex+1)
}
} else if gesture.direction == .right {
if (self.tabBarController?.selectedIndex)! > 0 {
thisTabController.animateToTab(toIndex: thisTabController.selectedIndex-1)
}
}
}
}
Related
I am having a no-show menuController and I have checked all of the suggestions in previous questions. It turns out the imageView I have implemented a UILongPressGestureRecognizer on, to show the menu, is returning False on calling .becomeFirstResponder just before setting up the menu controller.
I am coding in swift 4 and can't figure out how to make the imageView return True to calling .becomeFirstResponder. Help!
/*********************************************************/
override func viewDidLoad() {
super.viewDidLoad()
// long tap to show menu that enables deletion of the image.
imageView_1.isUserInteractionEnabled = true
let longPressRecogniser = UILongPressGestureRecognizer(target: self, action: #selector(longPressOnImage(_:)))
//longPressRecogniser.numberOfTapsRequired = 1
//longPressRecogniser.numberOfTouchesRequired = 1
longPressRecogniser.minimumPressDuration = 0.5
imageView_1.addGestureRecognizer(longPressRecogniser)
imageView_1.image = placeHolderImage_1
imageView_2.image = placeHolderImage_2
}
/*********************************************************/
#IBAction func longPressOnImage(_ gestureRecognizer: UILongPressGestureRecognizer) {
print(#function)
if gestureRecognizer.state == .began {
//print("gestureRecognizer.state == .began")
self.tappedView = gestureRecognizer.view!
if tappedView.canResignFirstResponder {
print("can resign first responder")
}
if tappedView.becomeFirstResponder() {
print("returned TRUE to becomeFirstResponder")
} else {
print("returned FALSE to becomeFirstResponder")
}
// Configure the shared menu controller
let menuController = UIMenuController.shared
// Configure the menu item to display
// Create a "delete" menu item
let deleteImage = UIMenuItem(title: "Delete", action: #selector(deleteImage_1))
menuController.menuItems = [deleteImage]
// Set the location of the menu in the view.
let location = gestureRecognizer.location(in: tappedView)
print("location = ", location)
let menuLocation = CGRect(x: location.x, y: location.y, width: 2, height: 2)
menuController.setTargetRect(menuLocation, in: tappedView)
//update the menu settings to force it to display my custom items
menuController.update()
// Show the menu.
menuController.setMenuVisible(true, animated: true)
print("menu should be visible now")
}
}
/*********************************************************/
#objc func deleteImage_1() {
print(#function)
}
My caveman debugging print statements output:
longPressOnImage
can resign first responder
returned FALSE to becomeFirstResponder
location = (207.0, 82.0)
menu should be visible now
Create a custom imageView class and override "canBecomeFirstResponder" property like this:
class ResponsiveImage : UIImageView{
override var canBecomeFirstResponder: Bool{
return true
}
}
Use this ResponsiveImage type and your code will work :)
Thank you to adri. Your answer is the solution to my problem.
I had read in other posts to similar questions about overriding var canBecomeFirstResponder but either overlooked it or it wasn't made explicit that a custom UIImageView class needs to be created.
Just to make it clear to newbies like me, the class of the imageView in storyBoard and its #IBOutlet in its viewController must typed as ResponsiveImage. If only one of these is changed a type casting error is reported.
Many thanks for ending my hours of frustration! :-)
I have a custom presentation controller which shows a UIViewController as a "bottom sheet" above the current ViewController, and allows an interactive gesture to dismiss the presented modal. The modal's modalPresentationStyle is set to .current, and the transitioningDelegate is set to my custom class during init(). The current code works perfectly on iOS 11 and 12, but appears to "freeze" the device on iOS 9 and 10.
Here is where the animation takes place. I have confirmed the presentedFrame and dismissedFrame are correct.
extension BottomSheetPresentationManager: UIViewControllerAnimatedTransitioning {
func transitionDuration(
using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 0.25
}
func interactionControllerForPresentation(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
return self
}
func interactionControllerForDismissal(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
return self
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
let key = presenting ? UITransitionContextViewControllerKey.to
: UITransitionContextViewControllerKey.from
let keyV = presenting ? UITransitionContextViewKey.to
: UITransitionContextViewKey.from
let controller = transitionContext.viewController(forKey: key)!
let view = transitionContext.view(forKey: keyV)!
if presenting {
transitionContext.containerView.addSubview(view)
}
let presentedFrame = transitionContext.finalFrame(for: controller)
var dismissedFrame = presentedFrame
switch direction {
case .left:
dismissedFrame.origin.x = -presentedFrame.width
case .right:
dismissedFrame.origin.x = transitionContext.containerView.frame.size.width
case .top:
dismissedFrame.origin.y = -presentedFrame.height
case .bottom:
dismissedFrame.origin.y = transitionContext.containerView.frame.size.height
}
let initialFrame = presenting ? dismissedFrame : presentedFrame
let finalFrame = presenting ? presentedFrame : dismissedFrame
// Runs when the animation finishes
let completionBlock: (Bool) -> Void = { (finished) in
// tell our transitionContext object that we've finished animating
if transitionContext.transitionWasCancelled {
if self.interactive {
transitionContext.cancelInteractiveTransition()
}
transitionContext.completeTransition(false)
} else {
if self.interactive {
finished ? transitionContext.finishInteractiveTransition() : transitionContext.cancelInteractiveTransition()
}
transitionContext.completeTransition(finished)
}
}
// Put what you want to animate here.
let animationBlock: () -> Void = {
view.frame = finalFrame
}
// Set up for the animation
let animationDuration = transitionDuration(using: transitionContext)
view.frame = initialFrame
// Perform a different animation based on whether we're interactive (performing a gesture) or not
if interactive {
// Do a linear animation so we match our dragging with our transition
UIView.animate(withDuration: animationDuration,
delay: 0,
options: .curveLinear,
animations: animationBlock,
completion: completionBlock)
} else {
// Do a spring animation with easing
UIView.animate(withDuration: animationDuration,
delay: 0,
usingSpringWithDamping: 0.8,
initialSpringVelocity: 0.45,
options: [.curveEaseInOut],
animations: animationBlock,
completion: completionBlock)
}
}
}
After much testing, I have figured out that the completion block on the UIView.animate block never gets called (completionBlock in the code), and in the Capture View Hierarchy view, it actually shows my presented view on top, with what looks like a screenshot of the view (UIVisualEffectView) directly under the presented menu.
What you are seeing there is my bottom menu (the UITableView with cells that you see in front), with a UIVisualEffectView behind it (appears to be a screenshot of the UICollection view behind that), and a UICollectionView that called the present() method for the menu.
What would cause the UIView.animate block not to complete? Is there any reason the behavior would differ between iOS 10 and 11? Any help would be greatly appreciated.
I made a custom modal transition by using UIViewControllerAnimatedTransitioning. After the transition has completed, a modally shown view controller fills part of parent view that some part of parent view controller is still visible.
I need to know how to detect tap on outside of shown view controller(or partially shown parent view controller) so I can use it to close the modal. I understand how to add gesture to a view but I cannot find which view to add a gesture to.
I looked through stackoverflow but there aren't example specifically for custom modal transition.
Here is a code for custom transition
class PartialSlideInAnimationController: NSObject, UIViewControllerAnimatedTransitioning {
var direction: SlideAnimationDirectionStyle
var duration: TimeInterval = 0.125
var presentedControllerWidth: CGFloat = 250
let fadeAlpha: CGFloat = 0.5
init(direction: SlideAnimationDirectionStyle) {
self.direction = direction
super.init()
}
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return TimeInterval(duration)
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
// Setup Views
guard let presentedFromVC = transitionContext.viewController(forKey: .from) else {transitionContext.completeTransition(false); return }
guard let presentingToVC = transitionContext.viewController(forKey: .to) else {transitionContext.completeTransition(false); return }
let contrainerView = transitionContext.containerView // アニメーションはこのViewで行われる、アニメーションを実装する presenter, presenteeをこの上に載せないとアニメーションが動かない
// Setup Frames
let positionHidden = CGRect(x: contrainerView.frame.width + 1, y: 0, width: presentedControllerWidth, height: contrainerView.frame.height)
let positionShown = CGRect(x: contrainerView.frame.width - presentedControllerWidth, y: 0, width: presentedControllerWidth, height: contrainerView.frame.height)
switch direction {
case .slideIn:
contrainerView.addSubview(presentingToVC.view)
presentingToVC.view.frame = positionHidden
UIView.animate(withDuration: duration, animations: {
presentingToVC.view.frame = positionShown
presentedFromVC.view.alpha = self.fadeAlpha
}, completion: { success in
transitionContext.completeTransition( success )
})
case .slideOut:
contrainerView.addSubview(presentedFromVC.view)
presentedFromVC.view.frame = positionShown
UIView.animate(withDuration: duration, animations: {
presentedFromVC.view.frame = positionHidden
presentingToVC.view.alpha = 1.0
}, completion: { success in
transitionContext.completeTransition( success )
})
}
}
}
Have you tried using UIGestureRecognizer yet? The UIGestureRecognizer can be utilized to recognize tap events, both inside a child view controller and a parent view controller. For swift 3, there should be a handleTapBehind function of the UIRecognizerDelegate that should allow you to do what you're looking for.
See if the what is documented here
See the "Swift 3.1 solution that works in both portrait and landscape" in the linked post.
I've seen posts around here that suggest that UIScrollViews should automatically scroll if a subview UITextField becomes the first responder; however, I can't figure out how to get this to work.
What I have is a UIViewController that has a UIScrollView and within the UIScrollView there are multiple textfields.
I know how to do this manually if necessary; however, from what I've been reading, it seems possible to have it autoscroll. Help please.
I hope this example will help you
You can scroll to any point by this code.
scrollView.contentOffset = CGPointMake(0,0);
So if you have textfield, it must have some x,y position on view, so you can use
CGPoint point = textfield.frame.origin ;
scrollView.contentOffset = point
This should do the trick,
But if you don't know when to call this code, so you should learn UITextFieldDelegate methods
Implement this method in your code
- (void)textFieldDidBeginEditing:(UITextField *)textField {
// Place Scroll Code here
}
I hope you know how to use delegate methods.
I know this question has already been answered, but I thought I would share the code combination that I used from #Adeel and #Basil answer, as it seems to work perfectly for me on iOS 9.
-(void)textFieldDidBeginEditing:(UITextField *)textField {
// Scroll to the text field so that it is
// not hidden by the keyboard during editing.
[scroll setContentOffset:CGPointMake(0, (textField.superview.frame.origin.y + (textField.frame.origin.y))) animated:YES];
}
-(void)textFieldDidEndEditing:(UITextField *)textField {
// Remove any content offset from the scroll
// view otherwise the scroll view will look odd.
[scroll setContentOffset:CGPointMake(0, 0) animated:YES];
}
I also used the animated method, it makes for a much smoother transition.
Here is the Swift 4 update to #Supertecnoboff's answer. It worked great for me.
func textFieldDidBeginEditing(_ textField: UITextField) {
scroll.setContentOffset(CGPoint(x: 0, y: (textField.superview?.frame.origin.y)!), animated: true)
}
func textFieldDidEndEditing(_ textField: UITextField) {
scroll.setContentOffset(CGPoint(x: 0, y: 0), animated: true)
}
Make sure to extend UITextFieldDelegate and set the textfields' delegate to self.
There is nothing you have to do manually. It is the default behavior. There are two possibilities as to why you are not seeing the behavior
The most likely reason is that the keyboard is covering your UITextField. See below for solution
The other possibility is that you have another UIScrollView somewhere in the view hierarchy between the UITextField and the UIScrollView that you want to auto scroll. This is less likely but can still cause problems.
For #1, you want to implement something similar to Apple's recommendations for Moving Content That Is Located Under the Keyboard. Note that the code provided by Apple does not account for rotation. For improvements on their code, check out this blog post's implementation of the keyboardDidShow method that properly translates the keyboard's frame using the window.
- (void)textFieldDidBeginEditing:(UITextField *)textField {
CGRect rect = [textField bounds];
rect = [textField convertRect:rect toView:self.scrollView];
rect.origin.x = 0 ;
rect.origin.y -= 60 ;
rect.size.height = 400;
[self.scrollView scrollRectToVisible:rect animated:YES];
}
You can use this function for autoScroll of UITextField
on UITextFieldDelegate
- (void)textFieldDidBeginEditing:(UITextField *)textField {
[self autoScrolTextField:textField onScrollView:self.scrollView];
}
- (void) autoScrolTextField: (UITextField *) textField onScrollView: (UIScrollView *) scrollView {
float slidePoint = 0.0f;
float keyBoard_Y_Origin = self.view.bounds.size.height - 216.0f;
float textFieldButtomPoint = textField.superview.frame.origin.y + (textField.frame.origin.y + textField.frame.size.height);
if (keyBoard_Y_Origin < textFieldButtomPoint - scrollView.contentOffset.y) {
slidePoint = textFieldButtomPoint - keyBoard_Y_Origin + 10.0f;
CGPoint point = CGPointMake(0.0f, slidePoint);
scrollView.contentOffset = point;
}
EDIT:
Im now using IQKeyboardManager
Kudos to the developer of this, you need to try this.
Solution
extension UIScrollView {
func scrollVerticallyToFirstResponderSubview(keyboardFrameHight: CGFloat) {
guard let firstResponderSubview = findFirstResponderSubview() else { return }
scrollVertically(toFirstResponder: firstResponderSubview,
keyboardFrameHight: keyboardFrameHight, animated: true)
}
private func scrollVertically(toFirstResponder view: UIView,
keyboardFrameHight: CGFloat, animated: Bool) {
let scrollViewVisibleRectHeight = frame.height - keyboardFrameHight
let maxY = contentSize.height - scrollViewVisibleRectHeight
if contentOffset.y >= maxY { return }
var point = view.convert(view.bounds.origin, to: self)
point.x = 0
point.y -= scrollViewVisibleRectHeight/2
if point.y > maxY {
point.y = maxY
} else if point.y < 0 {
point.y = 0
}
setContentOffset(point, animated: true)
}
}
extension UIView {
func findFirstResponderSubview() -> UIView? { getAllSubviews().first { $0.isFirstResponder } }
func getAllSubviews<T: UIView>() -> [T] { UIView.getAllSubviews(from: self) as [T] }
class func getAllSubviews<T: UIView>(from parenView: UIView) -> [T] {
parenView.subviews.flatMap { subView -> [T] in
var result = getAllSubviews(from: subView) as [T]
if let view = subView as? T { result.append(view) }
return result
}
}
}
Full Sample
Do not forget to paste the Solution code here
import UIKit
class ViewController: UIViewController {
private weak var scrollView: UIScrollView!
private lazy var keyboard = KeyboardNotifications(notifications: [.willHide, .willShow], delegate: self)
override func viewDidLoad() {
super.viewDidLoad()
let scrollView = UIScrollView()
view.addSubview(scrollView)
scrollView.translatesAutoresizingMaskIntoConstraints = false
scrollView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
scrollView.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor).isActive = true
scrollView.rightAnchor.constraint(equalTo: view.safeAreaLayoutGuide.rightAnchor).isActive = true
scrollView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true
scrollView.contentSize = CGSize(width: view.frame.width, height: 1000)
scrollView.isScrollEnabled = true
scrollView.indicatorStyle = .default
scrollView.backgroundColor = .yellow
scrollView.keyboardDismissMode = .interactive
self.scrollView = scrollView
addTextField(y: 20)
addTextField(y: 300)
addTextField(y: 600)
addTextField(y: 950)
}
private func addTextField(y: CGFloat) {
let textField = UITextField()
textField.borderStyle = .line
scrollView.addSubview(textField)
textField.translatesAutoresizingMaskIntoConstraints = false
textField.topAnchor.constraint(equalTo: scrollView.topAnchor, constant: y).isActive = true
textField.leftAnchor.constraint(equalTo: scrollView.leftAnchor, constant: 44).isActive = true
textField.widthAnchor.constraint(equalToConstant: 120).isActive = true
textField.heightAnchor.constraint(equalToConstant: 44).isActive = true
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
keyboard.isEnabled = true
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
keyboard.isEnabled = false
}
}
extension ViewController: KeyboardNotificationsDelegate {
func keyboardWillShow(notification: NSNotification) {
guard let userInfo = notification.userInfo as? [String: Any],
let keyboardFrame = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect else { return }
scrollView.contentInset.bottom = keyboardFrame.height
scrollView.scrollVerticallyToFirstResponderSubview(keyboardFrameHight: keyboardFrame.height)
}
func keyboardWillHide(notification: NSNotification) {
scrollView.contentInset.bottom = 0
}
}
/// Solution
extension UIScrollView {
func scrollVerticallyToFirstResponderSubview(keyboardFrameHight: CGFloat) {
guard let firstResponderSubview = findFirstResponderSubview() else { return }
scrollVertically(toFirstResponder: firstResponderSubview,
keyboardFrameHight: keyboardFrameHight, animated: true)
}
private func scrollVertically(toFirstResponder view: UIView,
keyboardFrameHight: CGFloat, animated: Bool) {
let scrollViewVisibleRectHeight = frame.height - keyboardFrameHight
let maxY = contentSize.height - scrollViewVisibleRectHeight
if contentOffset.y >= maxY { return }
var point = view.convert(view.bounds.origin, to: self)
point.x = 0
point.y -= scrollViewVisibleRectHeight/2
if point.y > maxY {
point.y = maxY
} else if point.y < 0 {
point.y = 0
}
setContentOffset(point, animated: true)
}
}
extension UIView {
func findFirstResponderSubview() -> UIView? { getAllSubviews().first { $0.isFirstResponder } }
func getAllSubviews<T: UIView>() -> [T] { UIView.getAllSubviews(from: self) as [T] }
class func getAllSubviews<T: UIView>(from parenView: UIView) -> [T] {
parenView.subviews.flatMap { subView -> [T] in
var result = getAllSubviews(from: subView) as [T]
if let view = subView as? T { result.append(view) }
return result
}
}
}
// https://stackoverflow.com/a/42600092/4488252
import Foundation
protocol KeyboardNotificationsDelegate: class {
func keyboardWillShow(notification: NSNotification)
func keyboardWillHide(notification: NSNotification)
func keyboardDidShow(notification: NSNotification)
func keyboardDidHide(notification: NSNotification)
}
extension KeyboardNotificationsDelegate {
func keyboardWillShow(notification: NSNotification) {}
func keyboardWillHide(notification: NSNotification) {}
func keyboardDidShow(notification: NSNotification) {}
func keyboardDidHide(notification: NSNotification) {}
}
class KeyboardNotifications {
fileprivate var _isEnabled: Bool
fileprivate var notifications: [NotificationType]
fileprivate weak var delegate: KeyboardNotificationsDelegate?
fileprivate(set) lazy var isKeyboardShown: Bool = false
init(notifications: [NotificationType], delegate: KeyboardNotificationsDelegate) {
_isEnabled = false
self.notifications = notifications
self.delegate = delegate
}
deinit { if isEnabled { isEnabled = false } }
}
// MARK: - enums
extension KeyboardNotifications {
enum NotificationType {
case willShow, willHide, didShow, didHide
var selector: Selector {
switch self {
case .willShow: return #selector(keyboardWillShow(notification:))
case .willHide: return #selector(keyboardWillHide(notification:))
case .didShow: return #selector(keyboardDidShow(notification:))
case .didHide: return #selector(keyboardDidHide(notification:))
}
}
var notificationName: NSNotification.Name {
switch self {
case .willShow: return UIResponder.keyboardWillShowNotification
case .willHide: return UIResponder.keyboardWillHideNotification
case .didShow: return UIResponder.keyboardDidShowNotification
case .didHide: return UIResponder.keyboardDidHideNotification
}
}
}
}
// MARK: - isEnabled
extension KeyboardNotifications {
private func addObserver(type: NotificationType) {
NotificationCenter.default.addObserver(self, selector: type.selector, name: type.notificationName, object: nil)
}
var isEnabled: Bool {
set {
if newValue {
for notificaton in notifications { addObserver(type: notificaton) }
} else {
NotificationCenter.default.removeObserver(self)
}
_isEnabled = newValue
}
get { _isEnabled }
}
}
// MARK: - Notification functions
extension KeyboardNotifications {
#objc func keyboardWillShow(notification: NSNotification) {
delegate?.keyboardWillShow(notification: notification)
isKeyboardShown = true
}
#objc func keyboardWillHide(notification: NSNotification) {
delegate?.keyboardWillHide(notification: notification)
isKeyboardShown = false
}
#objc func keyboardDidShow(notification: NSNotification) {
isKeyboardShown = true
delegate?.keyboardDidShow(notification: notification)
}
#objc func keyboardDidHide(notification: NSNotification) {
isKeyboardShown = false
delegate?.keyboardDidHide(notification: notification)
}
}
If you have multiple textfields say Textfield1, Textfield2, Textfield3 and you want to scroll the scrollview along the y-axis when textfield2 becomes first responder:
if([Textfield2 isFirstResponder])
{
scrollView.contentOffset = CGPointMake(0,yourY);
}
As Michael McGuire mentioned in his point #2 above, the system's default behavior misbehaves when the scroll view contains another scroll view between the text field and the scroll view. I've found that the misbehavior also occurs when there's a scroll view merely next to the text field (both embedded in the scroll view that needs to be adjusted to bring the text field into view when the text field wants to start editing. This is on iOS 12.1.
But my solution is different from the above. In my top-level scroll view, which is sub-classed so I can add properties and override methods, I override scrollRectToVisible:animated:. It simply calls its [super scrollRectToVisible:animated:] unless there's a property set that tells it to adjust the rect passed in, which is the frame of the text field. When the property is non-nil, it is a reference to the UITextField in question, and the rect is adjusted so that the scroll view goes further than the system thought it would. So I put this in the UIScrollView's sub-classed header file:
#property (nullable) UITextField *textFieldToBringIntoView;
(with appropriate #synthesize textFieldToBringIntoView; in the implementation. Then I added this override method to the implementation:
- (void)scrollRectToVisible:(CGRect)rect animated:(BOOL)how
{
if (textFieldToBringIntoView) {
// Do whatever mucking with `rect`'s origin needed to make it visible
// based on context or its spatial relationship with the other
// view that the system is getting confused by.
textFieldToBringIntoView = nil; // Go back to normal
}
[super scrollRectToVisible:rect animated:how];
}
In the delegate method for the UITextField for when it's about to begin editing, just set textFieldToBringIntoView to the textField in question:
- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
// Ensure it scrolls into view so that keyboard doesn't obscure it
// The system is about to call |scrollRectIntoView:| for the scrolling
// superview, but the system doesn't get things right in certain cases.
UIScrollView *parent = (UIScrollView *)textField.superview;
// (or figure out the parent UIScrollView some other way)
// Tell the override to do something special just once
// based on this text field's position in its parent's scroll view.
parent.textFieldToBringIntoView = textField;
// The override function will set this back to nil
return(YES);
}
It seems to work. And if Apple fixes their bug, it seems like it might still work (fingers crossed).
Building off of Vasily Bodnarchuk's answer I created a gist with a simple protocol that you can implement and it'll do it all for you.
All you need to do is call registerAsTextDisplacer()
I created a BaseViewController in my project and made that implement it
https://gist.github.com/CameronPorter95/cb68767f5f8052fdc70293c167e9430e
Other solutions I saw, let you set the offset to the origin of the textField but this makes the scroller view go beyond it bounds.
I did this adjustment to the offset instead to not go beyond the bottom nor the top offsets.
Set the keyboardHeightConstraint to the bottom of the page.
When the keyboard shows, update its constraint's constant to negative the keyboard height.
Then scroll to the responderField as we will show below.
#IBOutlet var keyboardHeightConstraint: NSLayoutConstraint?
var responderField: String?
#objc func keyboardNotification(notification: NSNotification) {
guard let keyboardValue = notification.userInfo [UIResponder.keyboardFrameEndUserInfoKey] as? NSValue else { return }
let keyboardHeight = keyboardValue.cgRectValue.height
keyboardHeightConstraint?.constant = -keyboardHeight
scroll(field: responderField!)
}
func textFieldDidBeginEditing(_ textField: UITextField) {
responderField = textField
}
Now we want to make sure we do not scroll greater than the bottom offset nor less than the top offset.
At the same time, we want to calculate the offset of the field's maxY value.
To do that, we subtract the scrollView.bounds.size.height from the maxY value.
let targetOffset = field.frame.maxY - scrollView.bounds.size.height
I found it nicer to scroll an extra distance of the keyboard height, but you could neglect that if you want to scroll right below the field.
let targetOffset = keyboardHeight + field.frame.maxY - scrollView.bounds.size.height
Remember to add the scrollView.contentInset.bottom if you have the tab bar visible.
func scroll(field: UITextField) {
guard let keyboardConstraintsConstant = keyboardHeightConstraint?.constant else { return }
let keyboardHeight = -keyboardConstraintsConstant
view.layoutIfNeeded()
let bottomOffset = scrollView.contentSize.height - scrollView.bounds.size.height + scrollView.contentInset.bottom
let topOffset = -scrollView.safeAreaInsets.top
let targetOffset = keyboardHeight + field.frame.maxY + scrollView.contentInset.bottom - scrollView.bounds.size.height
let adjustedOffset = targetOffset > bottomOffset ? bottomOffset : (targetOffset < topOffset ? topOffset : targetOffset)
scrollView.setContentOffset(CGPoint(x: 0, y: adjustedOffset), animated: true)
}
If you have scrollView and tableView with invalidating intrinsicContentSize as the subview, you can disable tableView scrolling in storyboard or set tableView.isScrollEnabled to false in code.
is it possible to determine whether my UIView is visible to the user or not?
My View is added as subview several times into a Tab Bar Controller.
Each instance of this view has a NSTimer that updates the view.
However I don't want to update a view which is not visible to the user.
Is this possible?
Thanks
For anyone else that ends up here:
To determine if a UIView is onscreen somewhere, rather than checking superview != nil, it is better to check if window != nil. In the former case, it is possible that the view has a superview but that the superview is not on screen:
if (view.window != nil) {
// do stuff
}
Of course you should also check if it is hidden or if it has an alpha > 0.
Regarding not wanting your NSTimer running while the view is not visible, you should hide these views manually if possible and have the timer stop when the view is hidden. However, I'm not at all sure of what you're doing.
You can check if:
it is hidden, by checking view.hidden
it is in the view hierarchy, by checking view.superview != nil
you can check the bounds of a view to see if it is on screen
The only other thing I can think of is if your view is buried behind others and can't be seen for that reason. You may have to go through all the views that come after to see if they obscure your view.
This will determine if a view's frame is within the bounds of all of its superviews (up to the root view). One practical use case is determining if a child view is (at least partially) visible within a scrollview.
Swift 5.x:
func isVisible(view: UIView) -> Bool {
func isVisible(view: UIView, inView: UIView?) -> Bool {
guard let inView = inView else { return true }
let viewFrame = inView.convert(view.bounds, from: view)
if viewFrame.intersects(inView.bounds) {
return isVisible(view: view, inView: inView.superview)
}
return false
}
return isVisible(view: view, inView: view.superview)
}
Older swift versions
func isVisible(view: UIView) -> Bool {
func isVisible(view: UIView, inView: UIView?) -> Bool {
guard let inView = inView else { return true }
let viewFrame = inView.convertRect(view.bounds, fromView: view)
if CGRectIntersectsRect(viewFrame, inView.bounds) {
return isVisible(view, inView: inView.superview)
}
return false
}
return isVisible(view, inView: view.superview)
}
Potential improvements:
Respect alpha and hidden.
Respect clipsToBounds, as a view may exceed the bounds of its superview if false.
The solution that worked for me was to first check if the view has a window, then to iterate over superviews and check if:
the view is not hidden.
the view is within its superviews bounds.
Seems to work well so far.
Swift 3.0
public func isVisible(view: UIView) -> Bool {
if view.window == nil {
return false
}
var currentView: UIView = view
while let superview = currentView.superview {
if (superview.bounds).intersects(currentView.frame) == false {
return false;
}
if currentView.isHidden {
return false
}
currentView = superview
}
return true
}
I benchmarked both #Audrey M. and #John Gibb their solutions.
And #Audrey M. his way performed better (times 10).
So I used that one to make it observable.
I made a RxSwift Observable, to get notified when the UIView became visible.
This could be useful if you want to trigger a banner 'view' event
import Foundation
import UIKit
import RxSwift
extension UIView {
var isVisibleToUser: Bool {
if isHidden || alpha == 0 || superview == nil {
return false
}
guard let rootViewController = UIApplication.shared.keyWindow?.rootViewController else {
return false
}
let viewFrame = convert(bounds, to: rootViewController.view)
let topSafeArea: CGFloat
let bottomSafeArea: CGFloat
if #available(iOS 11.0, *) {
topSafeArea = rootViewController.view.safeAreaInsets.top
bottomSafeArea = rootViewController.view.safeAreaInsets.bottom
} else {
topSafeArea = rootViewController.topLayoutGuide.length
bottomSafeArea = rootViewController.bottomLayoutGuide.length
}
return viewFrame.minX >= 0 &&
viewFrame.maxX <= rootViewController.view.bounds.width &&
viewFrame.minY >= topSafeArea &&
viewFrame.maxY <= rootViewController.view.bounds.height - bottomSafeArea
}
}
extension Reactive where Base: UIView {
var isVisibleToUser: Observable<Bool> {
// Every second this will check `isVisibleToUser`
return Observable<Int>.interval(.milliseconds(1000),
scheduler: MainScheduler.instance)
.map { [base] _ in
return base.isVisibleToUser
}.distinctUntilChanged()
}
}
Use it as like this:
import RxSwift
import UIKit
import Foundation
private let disposeBag = DisposeBag()
private func _checkBannerVisibility() {
bannerView.rx.isVisibleToUser
.filter { $0 }
.take(1) // Only trigger it once
.subscribe(onNext: { [weak self] _ in
// ... Do something
}).disposed(by: disposeBag)
}
Tested solution.
func isVisible(_ view: UIView) -> Bool {
if view.isHidden || view.superview == nil {
return false
}
if let rootViewController = UIApplication.shared.keyWindow?.rootViewController,
let rootView = rootViewController.view {
let viewFrame = view.convert(view.bounds, to: rootView)
let topSafeArea: CGFloat
let bottomSafeArea: CGFloat
if #available(iOS 11.0, *) {
topSafeArea = rootView.safeAreaInsets.top
bottomSafeArea = rootView.safeAreaInsets.bottom
} else {
topSafeArea = rootViewController.topLayoutGuide.length
bottomSafeArea = rootViewController.bottomLayoutGuide.length
}
return viewFrame.minX >= 0 &&
viewFrame.maxX <= rootView.bounds.width &&
viewFrame.minY >= topSafeArea &&
viewFrame.maxY <= rootView.bounds.height - bottomSafeArea
}
return false
}
I you truly want to know if a view is visible to the user you would have to take into account the following:
Is the view's window not nil and equal to the top most window
Is the view, and all of its superviews alpha >= 0.01 (threshold value also used by UIKit to determine whether it should handle touches) and not hidden
Is the z-index (stacking value) of the view higher than other views in the same hierarchy.
Even if the z-index is lower, it can be visible if other views on top have a transparent background color, alpha 0 or are hidden.
Especially the transparent background color of views in front may pose a problem to check programmatically. The only way to be truly sure is to make a programmatic snapshot of the view to check and diff it within its frame with the snapshot of the entire screen. This won't work however for views that are not distinctive enough (e.g. fully white).
For inspiration see the method isViewVisible in the iOS Calabash-server project
The simplest Swift 5 solution I could come up with that worked in my situation (I was looking for a button embedded in my tableViewFooter).
John Gibbs solution also worked but in my cause I did not need all the recursion.
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let viewFrame = scrollView.convert(targetView.bounds, from: targetView)
if viewFrame.intersects(scrollView.bounds) {
// targetView is visible
}
else {
// targetView is not visible
}
}
In viewWillAppear set a value "isVisible" to true, in viewWillDisappear set it to false. Best way to know for a UITabBarController subviews, also works for navigation controllers.
Another useful method is didMoveToWindow()
Example: When you push view controller, views of your previous view controller will call this method. Checking self.window != nil inside of didMoveToWindow() helps to know whether your view is appearing or disappearing from the screen.
This can help you figure out if your UIView is the top-most view. Can be helpful:
let visibleBool = view.superview?.subviews.last?.isEqual(view)
//have to check first whether it's nil (bc it's an optional)
//as well as the true/false
if let visibleBool = visibleBool where visibleBool { value
//can be seen on top
} else {
//maybe can be seen but not the topmost view
}
try this:
func isDisplayedInScreen() -> Bool
{
if (self == nil) {
return false
}
let screenRect = UIScreen.main.bounds
//
let rect = self.convert(self.frame, from: nil)
if (rect.isEmpty || rect.isNull) {
return false
}
// 若view 隐藏
if (self.isHidden) {
return false
}
//
if (self.superview == nil) {
return false
}
//
if (rect.size.equalTo(CGSize.zero)) {
return false
}
//
let intersectionRect = rect.intersection(screenRect)
if (intersectionRect.isEmpty || intersectionRect.isNull) {
return false
}
return true
}
In case you are using hidden property of view then :
view.hidden (objective C) or view.isHidden(swift) is read/write property. So you can easily read or write
For swift 3.0
if(view.isHidden){
print("Hidden")
}else{
print("visible")
}