I have an app with a PageViewController and I want to make my own custom PageViewController indicator. Everything is all set up. The only thing I need to do now is to figure out how to tell when the view controller's view has changed and what view it is currently on.
I have linked to this demo. In the first part I am clicking on the buttons at the top to change the page and the slider indicating what the current page is working, however after that I swipe my finger to change the controller, and I want to make the slider indicator to move with the page.
Here I had commented what to do for getting current Page index using PageViewController
func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool)
{
if (completed)
{
//No need as we had Already managed This action in other Delegate
}
else
{
///Update Current Index
Manager.pageindex = Manager.lastIndex
///Post notification to hide the draggable Menu
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "updateLabelValue"), object: nil)
}
}
//MARK: Check Transition State
func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController])
{
///Update Last Index
Manager.lastIndex = Manager.pageindex
///Update Index
Manager.pageindex = pages.index(of: pendingViewControllers[0])!
///Post notification to hide the draggable Menu
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "updateLabelValue"), object: nil)
}
I Had used Notification Observer to Notify the main controller about page Change and Performing some action
Manager is my struct , that hold the current page number , you can make hold the index in struct or in class wherever you want
My struct class
//Struct Class
struct Manager
{
///Current Page Index
static var pageindex :Int = 0
///Last Index
static var lastIndex :Int = 0
}
Main usage
switch Manager.pageindex
{
case 0:
self.mainHomeLabel.text = "VC1"
case 1:
self.mainHomeLabel.text = "VC2"
case 2:
self.mainHomeLabel.text = "VC3"
default:
self.mainHomeLabel.text = "VC1"
}
Note Any queries in the respective code Please ask
Update - Added Demo Project Link
Link - https://github.com/RockinGarg/PageViewController-Demo.git
If you have an array of the pages you're showing then you could use the UIPageViewControllerDelegate to detect page changes. More specifically this function https://developer.apple.com/documentation/uikit/uipageviewcontrollerdelegate/1614091-pageviewcontroller as it will tell you what you are about to transition to. You could then determine what page you are on based on the view controller that is about to be presented.
Related
I have multiple view controllers. Something like this:
ViewControllerA
ViewControllerB
ViewControllerC
I use these as my UIPageViewController's view controllers, (as pages).
Each one of them has scrollable UITextViews inside. I cannot disable scrolling because text length should be flexible.
When I scroll the textview, UIPageViewControllerDataSource's viewControllerBefore or viewControllerAfter also is being triggered. How can I prevent this?
Can I disable vertical gestures for UIPageViewController and prevent clashes? Or is there some other way to stop them working at the same time? I want to change page only on horizontal gesture, and scroll the text view only on vertical gesture. But I don't know how to do it. What should I do?
Edit: Thank you #DonMag and #BulatYakupov for trying to help me and warning me about the given information is not enough. I had some restriction on code sharing. Today I found another way. But first here how my screen looks :
I was swiping to turn the page with page curl.
When I scroll the text, it was also triggering viewControllerBefore or viewControllerAfter. It wasn't changing the page, but It was triggering my view controller creating function. This function keep track of current index on an array to supply data to vc creation.
It is something like this:
class myCustomVC: UIViewController {
let textView = UITextView()
}
class PageVCDataService {
var array = ["John","Josh","Joe","Harvy"]
//keeping track of the current index for suppling correct text from array for every page
var currentIndex = 0
func createAfterPage() -> UIViewController {
currentIndex += 1
return createVC(page :array[currentIndex])
}
func createBeforePage() -> UIViewController {
currentIndex -= 1
return createVC(page :array[currentIndex])
}
func createVC(page : String) ->UIViewController {
let vc = myCustomVC()
vc.textView.text = page
return vc
}
}
class PageVC : UIPageViewController {
let dataService = PageVCDataService()
// ...some code
}
extension PageVC: UIPageViewControllerDataSource {
func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
return dataService.createBeforePage()
}
func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
return dataService.createAfterPage()
}
}
It wasn't changing the page but it was changing the index. For example if I scroll the text and if my current index at 10 (page 11), my current index was changing to 9. When I swipe for next page, next page was the same page because index was going 9 to 10, which is the same index at the beginning.
So i implemented UITextViewDelegate and used scrollViewDidScroll method. Every time text view scrolls, it send a notification to my data service class, tell it to check if the text on the screen and the text at the current index is same. If it's not, my function find the index for the text on the screen and corrects current index.
It is an ugly solution but maybe it can help someone else.
I'm working on an app that displays a today extension with some information. When I tap on the today extension, it opens the app and navigates to a subview from the root to display the information. Normally the user would then click the back arrow to go back to the main view, but there is no way to tell if this is actually done. It is possible for the user to go back to the today extension and tap again. When this is done, the subview is opened once again with new information. If this is done a bunch of times, I end up with a bunch of instances of the subview and I have to click the back button on each of them to get back to the main view.
My question: Is it possible to check if the subview is already visible? I'd like to be able to just send updated information to it, instead of having to display an entirely new view.
I am currently handling this by keeping the instance of the UIViewController at the top of my root. If it is not nil, then I just pass the information to it and redraw. If it is nil, then I call performSegue and create a new one.
I just think that there must be a better way of handling this.
Edit: Thanks to the commenter below, I came up with this code that seems to do what I need.
if let quoteView = self.navigationController?.topViewController as? ShowQuoteVC {
quoteView.updateQuoteInformation(usingQuote: QuoteService.instance.getQuote(byQuoteNumber: quote))
}
else {
performSegue(withIdentifier: "showQuote", sender: quote)
}
This is different from the suggested post where the answer is:
if (self.navigationController.topViewController == self) {
//the view is currently displayed
}
In this case, it didn't work because I when I come in to the app from the Today Extension, it goes to the root view controller. I needed to check whether a subview is being displayed, and self.navigationController.topViewcontroller == self will never work because I am not checking to see if the top view controller is the root view controller. The suggestions in this post are more applicable to what I am trying to accomplish.
u can use this extension to check for currently displayed through the UIApplication UIViewController:
extension UIApplication {
class func topViewController(base: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
if let nav = base as? UINavigationController {
return topViewController(base: nav.visibleViewController)
}
if let tab = base as? UITabBarController {
if let selected = tab.selectedViewController {
return topViewController(base: selected)
}
}
if let presented = base?.presentedViewController {
return topViewController(base: presented)
}
return base
}
}
and usage example:
if let topController = UIApplication.topViewController() {
if !topController.isKind(of: MainViewController.self) { //MainViewController- the controller u wish to equal its type
// do action...
}
}
In my SpriteKit game, I have two View Controllers. One is my MenuViewController, which has an SKView/SKScene in it - this handles the level selection, etc.
I then have my GameSceneViewController - this has an ARSKView/SKScene in it. When a user completes multiple levels and, for example, earns 3 stars for each one, and then uses the pause menu to go back to the MenuViewController, the stars that show for each level are (obviously) not refreshed.
This is because at the moment, when a user wants to go back to the MenuViewController, I simply call:
self.dismiss(animated: true, completion: nil)
I was wondering if there is a function I could call to "refresh" the MenuSceneController when a user dismisses the GameSceneViewController.
First of all add the following method to MenuSceneController
class MenuSceneController: UIViewController {
func reloadScene() {
// write here your logic to reload the scene
}
}
Now when you dismiss GameSceneViewController you can call that method
class GameSceneViewController: UIViewController {
func goBackToMenu() {
guard let menuSceneController = presentingViewController as? MenuSceneController else {
debugPrint("Error, this view controller was not presented by a MenuSceneController")
return
}
self.dismiss(animated: true) {
menuSceneController.reloadScene()
}
}
}
I have to move the UIView in only last UITextField in Swift 3.0 on mentioned below delegate method using tag,
func textFieldDidBeginEditing(_ textField: UITextField) {
if (textField.tag == 4){
//UIView Up
}
}
func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
if (textField.tag == 4){
//UIView Down
}
return true
}
I tried many codes but none of them are working like notification,..etc.
You need to add Observers into the NotificationCenter for listening to both when Keyboard goes up and down (i'll assume your textfield outlet is lastTextField for this example to work but this obviously have to be adapted to whatever name you've had provide for it)
IBOutlet weak var passwordTextField: UITextField!
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: .UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: .UIKeyboardWillHide, object: nil)
(Code above can be added in viewDidLoad())
Then you add methods to be executed when those notifications arrive, like this:
func keyboardWillShow(_ notification:Notification) {
if view.frame.origin.y >= 0 && lastTextField.isFirstResponder {
view.frame.origin.y -= getKeyboardHeight(notification)
}
}
func keyboardWillHide(_ notification:Notification) {
if view.frame.origin.y < 0 {
view.frame.origin.y += getKeyboardHeight(notification)
}
}
Validations within those methods prevent double execution like moving up/down twice when moving between textfields without resigning first responder which is common in cases like your (i assume your doing this for a form hence the clarification you only need it for the fourth textfield). Notice i'm only doing validation in for the specified textfield (with its outlet lastTextField) in the keyboardWillShow method, this in case you move thor another textfield while the keyboard is shown and resign responder from it in which case, even though it isn't the original place where you started, the view will return to its original place when the keyboard is hidden.
You'll also need a method for getting keyboard's height, this one can help with that:
func getKeyboardHeight(_ notification:Notification) -> CGFloat {
let userInfo = notification.userInfo
let keyboardSize = userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue // of CGRect
return keyboardSize.cgRectValue.height
}
Let me know how it goes but i just tested this same code on my app and it works so you should be fine.
PS: pay close attention to the storyboard (if you're using it) and that delegate for textfields are set up properly.
The problem you are trying to remedy is rather complicated, because it requires you to:
Find the textField which is firstResponder
Calculate where that TextField is relative to it's superViews
Determine the distance for the animation, so that the containing
superview doesnt jump out of the window, or jumps too
much/repeatedly
Animate the proper superView.
As you can see.. it's quite the algorithm. But luckily, I can help. However, this only works for a hierarchy which has the following layout:
superView (view in the case of UIViewController) > (N)containerSubviews > textFields
where N is an integer
or the following:
superView (view in the case of UIViewController) > textFields
The idea is to animate superView, based on which textField is firstResponser, and to calculate if it's position inside of the SCREEN implies that it either partially/totally obstructed by the Keyboard or that it is not positioned the way you want for editing. The advantage to this, over simply moving up the superView when the keyboard is shown in an arbitrary manner, is that your textField might not be positioned properly (ie; obstructed by the statusbar), and in the case where your textfields are in a ScrollView/TableView or CollectionView, you can simply scroll the texfield into the place you want instead. This allows you to compute that desired location.
First you need a method which will parse through a given superView, and look for which of it's subViews isFirstResponder:
func findActiveTextField(subviews : [UIView], textField : inout UITextField?) {
for view in subviews {
if let tf = view as? UITextField {
guard !tf.isFirstResponder else {
textField = tf; break
return
}
} else if !subviews.isEmpty {
findActiveTextField(subviews: view.subviews, textField: &textField)
}
}
}
Second, to aleviate the notification method, also make a method to manage the actual animation:
func moveFromDisplace(view: UIView, keyboardheight: CGFloat, comp: #escaping (()->())) {
//You check to see if the view passed is a textField.
if let texty = view as? UITextField {
//Ideally, you set some variables to animate with.
//Next step, you determine which textField you're using.
if texty == YourTextFieldA {
UIView.animate(withDuration: 0.5, animations: {
self./*the proper superView*/.center.y = //The value needed
})
comp()
return
}
if texty == YourTextFieldB {
// Now, since you know which textField is FirstResponder, you can calculate for each textField, if they will be cropped out by the keyboard or not, and to animate the main view up accordingly, or not if the textField is visible at the time the keyboard is called.
UIView.animate(withDuration: 0.5, animations: {
self./*the proper superView*/.center.y = //The Value needed
})
comp()
return
}
}
}
Finally, the method which is tied to the notification for the keyboardWillShow key; in this case, i have a UIViewController, with an optional view called profileFlow containing a bunch of UITextFields
func searchDisplace(notification: NSNotification) {
guard let userInfo:NSDictionary = notification.userInfo as NSDictionary else { return }
guard let keyboardFrame:NSValue = userInfo.value(forKey: UIKeyboardFrameEndUserInfoKey) as? NSValue else { return }
let keyboardRectangle = keyboardFrame.cgRectValue
let keyboardHeight = keyboardRectangle.height
let keybheight = keyboardHeight
var texty : UITextField? //Here is the potential textfield
var search : UISearchBar? //In my case, i also look out for searchBars.. So ignore this.
guard let logProfile = profileFlow else { return }
findActiveTextField(subviews: [logProfile], textField: &texty)
//Check if the parsing method found anything...
guard let text = texty else {
//Found something.. so determine if it should be animated..
moveFromDisplace(view: searchy, keybheight: keybheight, comp: {
value in
search = nil
})
return
}
//Didn't find anything..
}
Finally, you tie in this whole logic to the notification:
NotificationCenter.default.addObserver(self, selector: #selector(searchDisplace(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
I can't provide more content to the code, since it all depends on your view hierarchy, and how you want things to animate. So it's up to you to figure that out.
On a side note, usually, if you have so many textfields that to lay them out properly means they overstep the length of the screen.. it's probable that you could simplify your layout. A way to make this algorithm better would be to make sure you have all your textfields in one containing view, which again can become heavy for when, say, you use AutoLayout constraints. Odds are if you're in this situation, you can probably afford to add a flow of several views etc.
There is also the fact that i've never really needed to use this for iPhone views, more for iPad views, and even then for large forms only (e-commerce). So perhaps if you're not in that category, it might be worth reviewing your layout.
Another approach to this, is to use my approach, but to instead check for specific textFields right in the findActiveTextField() method if you only have a handful of textfields, and to animate things within findActiveTextField() as well if you know all of the possible positions they can be in.
Either way, i use inout parameters in this case, something worth looking into if you ask me.
I have a UIViewController with a UILabel that needs to display either "lbs" or "kg". My app has a settings screen (another UIViewController) that is presented modally over the first view controller and the user can select either of the two units and save their preference. If the units are changed and the modal settings screen is dismissed, I of course want the label on the first view controller to be updated with the new units value (but without refreshing the whole view). I thought I knew how to make it work, but evidently I don't.
On my modal settings screen, I have a UISegmentedControl to allow the user to select units. Anytime it's changed, this function updates userDefaults:
func saveUnitsSelection() {
if unitsControl.selectedSegmentIndex == 0 {
UserDefaultsManager.sharedInstance.preferredUnits = Units.pounds.rawValue
} else {
UserDefaultsManager.sharedInstance.preferredUnits = Units.kilograms.rawValue
}
}
Then they would likely dismiss the settings screen. So, I added this to viewDidLoad in my first view controller:
override func viewDidLoad() {
super.viewDidLoad()
let preferredUnits = UserDefaultsManager.sharedInstance.preferredUnits
units.text = preferredUnits
}
That didn't work, so I moved it to viewWillAppear() and that didn't work either. I did some research and some caveman debugging and found out that neither of those functions is called after the view has been loaded/presented the first time. It seems that viewWillAppear will be called a second time if I'm working within a hierarchy of UITableViewControllers managed by a UINavigationController, but isn't called when I dismiss my modal UIViewController to reveal the UIViewController underneath it.
Edit 1:
Here's the view hierarchy I'm working with:
I'm kinda stuck at this point and not sure what to try next.
Edit 2:
The user can tap a 'Done' button in the navigation bar and when they do, the dismissSettings() function dismisses the Settings view:
class SettingsViewController: UITableViewController {
let preferredUnits = UserDefaultsManager.sharedInstance.preferredUnits
// some other variables set here
override func viewDidLoad() {
super.viewDidLoad()
self.navigationController?.navigationBar.topItem?.title = "Settings"
navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Done", style: .Plain, target: self, action: #selector(self.dismissSettings(_:)))
if preferredUnits == Units.pounds.rawValue {
unitsControl.selectedSegmentIndex = 0
} else {
unitsControl.selectedSegmentIndex = 1
}
}
func dismissSettings(sender: AnyObject?) {
navigationController?.dismissViewControllerAnimated(true, completion: nil)
}
}
THE REAL PROBLEM
You misspelled viewWillAppear. You called it:
func viewWillAppear()
As far as Cocoa Touch is concerned, this is a random irrelevant function that hooks into nothing. You meant:
override func viewWillAppear(animated: Bool)
The full name of the first function is: "viewWillAppear"
The full name of the second function is: "viewWillAppear:animated"
Once you get used to this, the extreme method "overloading" that Cocoa Touch uses gets easier.
This is very different in other languages where you might at least get a warning.
The other lesson that everyone needs to learn when posting a question is: Include All Related Code!
Useful logging function I use instead of print or NSLog, to help find these things:
class Util {
static func log(message: String, sourceAbsolutePath: String = #file, line: Int = #line, function: String = #function, category: String = "General") {
let threadType = NSThread.currentThread().isMainThread ? "main" : "other"
let baseName = (NSURL(fileURLWithPath: sourceAbsolutePath).lastPathComponent! as NSString).stringByDeletingPathExtension ?? "UNKNOWN_FILE"
print("\(NSDate()) \(threadType) \(baseName) \(function)[\(line)]: \(message)")
}
}
[Remaining previous discussion removed as it was incorrect guesses]