I have a fairly simple code which, upon clicking a button, adds a randomly colored UIView to a UIStackView, and upon a different button click, removes a random UIView from the UIStackView.
Here's the code:
import UIKit
class ViewController: UIViewController, Storyboarded {
weak var coordinator: MainCoordinator?
#IBOutlet weak var stackView: UIStackView!
var tags: [Int] = []
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func buttonPressed(_ sender: UIButton) {
switch sender.tag {
case 10:
let view = UIView(frame: CGRect(x: 0, y: 0, width: stackView.frame.width, height: 20))
var number = Int.random(in: 0...10000)
while tags.contains(number) {
number = Int.random(in: 0...10000)
}
tags.append(number)
view.tag = number
view.backgroundColor = .random()
stackView.addArrangedSubview(view)
case 20:
if tags.count == 0 {
print("Empty")
return
}
let index = Int.random(in: 0...tags.count - 1)
let tag = tags[index]
tags.remove(at: index)
if let view = stackView.arrangedSubviews.first(where: { $0.tag == tag }) {
stackView.removeArrangedSubview(view)
}
default:
break
}
}
}
extension CGFloat {
static func random() -> CGFloat {
return CGFloat(arc4random()) / CGFloat(UInt32.max)
}
}
extension UIColor {
static func random() -> UIColor {
return UIColor(
red: .random(),
green: .random(),
blue: .random(),
alpha: 1.0
)
}
}
I'm not using removeFromSuperview on purpose - since I would (later) want to reuse those removed UIViews, and that is why I'm using removeArrangedSubview.
The issue I'm facing is:
All UIViews are removed as expected (visually of course, I know they're still in the memory) until I reach the last one - which, even though was removed, still appears and filling the entire UIStackView.
What am I missing here?
You can understand removeArrangedSubview is for removing constraints that were assigned to the subview. Subviews are still in memory and also still inside the parent view.
To achieve your purpose, you can define an array as your view controller's property, to hold those subviews, then use removeFromSuperview.
Or use .isHidden property on any subview you need to keep it in memory rather than removing its contraints. You will see the stackview do magical things to all of its subviews.
let subview = UIView()
stackView.addArrangedSubview(subview)
func didTapButton(sender: UIButton) {
subview.isHidden.toggle()
}
Last, addArrangedSubview will do two things: add the view to superview if it's not in superview's hierachy and add contraints for it.
View is initialized with following constraints
View.snp.makeConstraints { (para) in
View.topConstraint = para.top.equalTo(parentview.snp.top).constraint
View.LeadingConstraint = para.leading.equalTo(parentview.snp.leading).constraint
View.TrailingConstraint = para.trailing.equalTo(parentview.snp.trailing).constraint
View.BottomConstraint =para.bottom.equalTo(parentview.snp.bottom).offset(-getheight).constraint
}
where getheight = parentview.frame.size.height/2 ;
when parentview changes its dimensions.View doesnt update its height as constraints are not called again.
any way to update or recall its constraints other the remakingConstraint which is not feasible at large scale.
Have tried:
View.updateConstraints()
View.setNeedsUpdateConstraints()
View.setNeedsLayout()
I need reference to each constraints because
if View.bottomTouch {
View.bottomConstraint.update(offset: View. BottomConstraint.layoutConstraints[0].constant + CurrentPoint - PreviousPoint)
}
Is there a reason you don't want to use 50% of the parent view height?
View.snp.makeConstraints { (para) in
para.top.equalTo(parentview.snp.top)
para.leading.equalTo(parentview.snp.leading)
para.trailing.equalTo(parentview.snp.trailing)
// 50% of the parent view height
para.height.equalTo(parentview.snp.height).multipliedBy(0.5)
// instead of this
//para.bottom.equalTo(parentview.snp.bottom).offset(-getheight)
}
Edit - after comments...
Keeping a reference to a constraint for the purposes of dragging a view is a very different question from "Keep the child view at 50% of the height of the parent view."
Give this a try...
It will create a cyan "parentView" with a blue "childView" (subview). Dragging the blue view (Pan Gesture) will drag its bottom up / down. Tapping anywhere (Tap Gesture) will toggle the insets on the frame of the parentView between 20 and 60.
When the parentView frame changes - either from the tap or, for example, on device rotation - the "childView" bottom will be reset to 50% of the height of the "parentView":
class ViewController: UIViewController {
let parentView = UIView()
let childView = UIView()
// childView bottom constraint
var bc: Constraint!
override func viewDidLoad() {
super.viewDidLoad()
parentView.backgroundColor = .cyan
childView.backgroundColor = .blue
parentView.addSubview(childView)
view.addSubview(parentView)
parentView.snp.makeConstraints { para in
para.top.leading.trailing.bottom.equalTo(self.view.safeAreaLayoutGuide).inset(20.0)
}
// childView's bottom constraint offset will be set in viewDidLayoutSubviews()
childView.snp.makeConstraints { para in
para.top.leading.trailing.equalToSuperview()
bc = para.bottom.equalToSuperview().constraint
}
let p = UIPanGestureRecognizer(target: self, action: #selector(panHandler(_:)))
childView.addGestureRecognizer(p)
let t = UITapGestureRecognizer(target: self, action: #selector(tapHandler(_:)))
view.addGestureRecognizer(t)
}
#objc func tapHandler(_ g: UITapGestureRecognizer) -> Void {
// on tap, toggle parentView inset
// between 20 and 60
// this will trigger viewDidLayoutSubviews(), where the childView bottom
// constraint will be reset to 50% of the parentView height
var i: CGFloat = 60.0
if parentView.frame.origin.x > 20 {
i = 20.0
}
parentView.snp.updateConstraints { para in
para.top.leading.trailing.bottom.equalTo(self.view.safeAreaLayoutGuide).inset(i)
}
}
#objc func panHandler(_ g: UIPanGestureRecognizer) -> Void {
let translation = g.translation(in: g.view)
// update bottom constraint constant
bc.layoutConstraints[0].constant += translation.y
// reset gesture translation
g.setTranslation(CGPoint.zero, in: self.view)
}
var parentViewHeight: CGFloat = 0.0
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
// reset childView's bottom constraint
// to 50% of its superView's height
// ONLY if parentView frame height has changed
if parentView.frame.height != parentViewHeight {
parentViewHeight = parentView.frame.height
bc.layoutConstraints[0].constant = -parentViewHeight * 0.5
}
}
}
Firstly, check whether the getheight value did update when the parent view layout change. In order to reload the existing constraints, you may need to call layoutIfNeeded() of your parent view.
I have view hierarchy like below in storyboard
here for content main constrains top = 0, leading = 0, trailing = 0, bottom = 0
here for scrollview constrains top = 0, leading = 0, trailing = 0, bottom = 0
here for View constrains top = 0, leading = 0, trailing = 0, bottom = 0
for ContentView constrains top = 0, leading = 0, trailing = 0
for TblReview constrains top = 0, leading = 0, trailing = 0, bottom = 20
for Productcollectionview constrains top = 0, leading = 0, trailing = 0, bottom = 20, height = 400
and i have Productcollectionview height outlet like below in swift file
and i don't want collectionview separate scrolling.. i want total view to scroll according to collectionview cells.. so for that i have written below code but with this code contentView and tblReview also scrolling upto productioncollectionview height i need contentView should scroll upto its content height and tblReview should scroll upto its rows
how to make scrolling separately to its height.
please help me to solve this issue
#IBOutlet weak var productCollHeight: NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
productCollectionView.addObserver(self, forKeyPath: "contentSize", options: .new, context: nil)
}
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
let collectionView = object as? UICollectionView
if collectionView == self.productCollectionView{
if(keyPath == "contentSize"){
if let newvalue = change?[.newKey]
{
let newsize = newvalue as! CGSize
self.productCollHeight.constant = newsize.height
}
}
}
}
#IBAction func aboutCompany(_ sender: UIButton){
self.productCollectionView.isHidden = true
self.tblReview.isHidden = true
self.contentView.isHidden = false
}
#IBAction func review(_ sender: UIButton){
self.productCollectionView.isHidden = true
self.tblReview.isHidden = false
self.contentView.isHidden = true
}
#IBAction func productOfSeller(_ sender: UIButton){
self.productCollectionView.isHidden = false
self.tblReview.isHidden = true
self.contentView.isHidden = true
}
and i am hiding and showing tblReview and contentView according to need
with the above code tblReview and contentView are also scrolling upto productCollectionView height.. please help me to solve this error
EDIT: share this seller is out of scrollview so here contentView height is not not so long but if i scroll the contentView also scrolling too long like productioncollectionview
this is contentView which is scrolling too long like productioncollectionview
if your all constraint are proper than just use it like this you don't need to count every time. UICollectionView has intrinsicContentSize it will count it properly.
final class ContentSizedCollectionView: UICollectionView {
override var contentSize:CGSize {
didSet {
invalidateIntrinsicContentSize()
}
}
override var intrinsicContentSize: CGSize {
layoutIfNeeded()
return CGSize(width: UIView.noIntrinsicMetric, height: contentSize.height)
}
}
put that code in controller or wherever you wan to put and assign ContentSizedCollectionView class to your collectionview.
NOTE: you can also use it with UITableView after creating for UITableView.
I need to have a nested UITableView in a tableView cell (actually, two tables in one cell) to show different lists with dynamic content (so, I need dynamic heights). My nested tables will not have scrolling—I need them just to order elements of different kinds, like texts, pictures, fields etc. To be more clear—the first level is the level of operations and every operation can have a variable amount of instructions and actions. Instructions and actions should be placed side by side and the operation cell should have the size of the tallest table.
There are no problems in nesting tables, but I faced a problem with the auto layout. I’ve tried everything that I could find, but with no success.
I tried height constraints for nested table views, which I update on the operation cell creation from tableview.contentsize.hight, but it seems that contentsize returns height based on the estimated size of every row, but not the actual size.
I tried to rewrite intrinsic content size of nested tables:
UITableView {
override var contentSize:CGSize {
didSet {
self.invalidateIntrinsicContentSize()
}
}
override var intrinsicContentSize: CGSize {
self.layoutIfNeeded()
return CGSize(width: UIViewNoIntrinsicMetric, height: contentSize.height)
}
}
Nothing works properly. Any ideas how it could be solved?
Thank you in advance.
Set Inner tableview my custom class AGTableView and height Constraint both are required,
this class set contantSize same table view height Constraint.
Check out Github AutoHeightIncrementTableViewDemo
class AGTableView: UITableView {
fileprivate var heightConstraint: NSLayoutConstraint!
override init(frame: CGRect, style: UITableViewStyle) {
super.init(frame: frame, style: style)
self.associateConstraints()
defaultInit()
}
required public init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.associateConstraints()
defaultInit()
}
func defaultInit(){
self.keyboardDismissMode = .onDrag
self.showsVerticalScrollIndicator = false
self.showsHorizontalScrollIndicator = false
self.tableFooterView = UIView(frame: .zero)
self.tableHeaderView = UIView(frame: .zero)
self.sectionFooterHeight = 0
self.sectionHeaderHeight = 0
}
override open func layoutSubviews() {
super.layoutSubviews()
if self.heightConstraint != nil {
self.heightConstraint.constant = self.contentSize.height
}
else{
print("Set a heightConstraint to set cocontentSize with same")
}
}
func associateConstraints() {
// iterate through all text view's constraints and identify
// height
for constraint: NSLayoutConstraint in constraints {
if constraint.firstAttribute == .height {
if constraint.relation == .equal {
heightConstraint = constraint
}
}
}
}
}
NOTE: Also set a estimatedRowHeight
self.rowHeight = UITableViewAutomaticDimension
self.estimatedRowHeight = height
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.