In my app, OneVC is one of child ViewControllers of PageViewController, TwoVC is the embed view controller of OneVC's Container View.
When the user drag the scroll view in OneVC, I want the drag action can be not just update the content in OneVC from web API, but notify TwoVC to update too.
Both OneVC and TwoVC will appear at interface at the same time when launch.
I'm following Apple's "Using Swift with Cocoa and Objective-C" "Key-Value Observing" instruction to imply KVO, but no notification is sent when the observed property changes. Please see below my code:
OneVC is the object to be observed.
class OneVC: UIViewController, UIScrollViewDelegate {
dynamic var isDragToUpdate = false
func scrollViewDidEndDragging(scrollView: UIScrollView, willDecelerate decelerate: Bool) {
if scrollView.contentOffset.y < -150 {
if isDragToUpdate {
isDragToUpdate = false
} else {
isDragToUpdate = true
}
print(isDragToUpdate)
}
}
}
TwoVC is the observer
class TwoVC: UIViewController {
let oneVC = OneVC()
override viewDidLoad() {
oneVC.addObserver(self, forKeyPath: "isDragToUpdate", options: [], context: nil)
}
override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
print("hoh")
guard keyPath == "isDragToUpdate" else {return}
print("hah")
}
deinit {
oneVC.removeObserver(self, forKeyPath: "isDragToUpdate")
}
}
I checked row by row, and find many other stackoverflow answers, but still no idea what's going wrong on my code, when drag and release the scrollview, none of "hoh" and "hah" are print in console, except print(isDragToUpdate) is printed properly.
Thank you in advance!
Related
I am trying to do KVO on an property of SKView but its not working.
I have tried it with .frame and it works like a charm, so why not also on .window ?
To clarify, I am using SpriteView in a SwiftUI app and I am trying to get the bounds of the View.
What I am after is to get the following before the App starts;
print (self.convertPoint(fromView: .zero) ). When I use this in
override func didMove
I'll get Nan/NaN. However Apple Code Level Support said this about using SpriteView and getting the bounds of a view.
The reason you are receiving NaN is that you are calling these methods
before the underlying SKView has been actually presented by SwiftUI,
which is an event that you have no visibility into, and no way to call
code when it happens.
However, when this event does occur, the SKScene’s view property will
have it’s window set from nil to a UIWindow. Therefore, you could use
KVO to observe when the window property is changed, and then make your
calls to convertPoint once there is a non-nil window.
I have so far this:
override func didMove(to view: SKView) {
observe.observe(object: view )
}
class Observer:SKScene {
var kvoToken: NSKeyValueObservation?
func observe(object: SKView) {
kvoToken = object.observe(\.window , options: [ .new] ) { (object, change) in
guard let value = change.newValue else { return }
print("New value is: \(value)")
print ("NEW", self.convertPoint(fromView: .zero) )
}
}
deinit {
kvoToken?.invalidate()
}
}
I have also tried to add an observer like so :
NotificationCenter.default.addObserver(view.window, selector: #selector(test(_:)), name: NSNotification.Name(rawValue: "TestNotification"), object: nil)
The above doesn't seem to do anything. So I am kinda stuck, any help would be appreciated.
The answer (probably) ..
I couldn't read the '.window' property of UIView, so I started to look for another observable property that would change as soon as UIWindow is != nil. I think I have found it in SKScene.view.frame . I am not entirely sure that this is a 100% good answer but it works.
class Observer: NSObject {
dynamic var kvoToken: NSKeyValueObservation?
func observe(object: SKScene ) {
kvoToken = object.observe(\.view?.frame , options: [ .new] ) { (object, change) in
guard let value = change.newValue else { return }
print("New value is: \(value)")
print ("CONVERTING", object.convertPoint(fromView: .zero) )
}
}
deinit {
kvoToken?.invalidate()
}
}
override func didMove(to view: SKView) {
viewer = view.scene
observe.observe(object: viewer )
}
I've successfully set my first view controller to STPAddCardViewController. I now need to get the user information in the STPPaymentCardTextField. Problem is, I'm used to using the storyboard to make outlets. How do I detect the STPPaymentCardTextField programmatically?
I've tried:
class ViewController: STPAddCardViewController, STPPaymentCardTextFieldDelegate {
let paymentCardTextField = STPPaymentCardTextField()
func paymentCardTextFieldDidChange(_ textField: STPPaymentCardTextField) {
print(paymentCardTextField.cardNumber)
//ERROR: printing nil in the console
}
}
But I'm getting nil as an output. Any help?
You should use either STPAddCardViewController, or STPPaymentCardTextField, not both. The SDK's ViewControllers are not designed to be extended. The intended use is:
class MyVC : STPAddCardViewControllerDelegate {
override func viewDidLoad() {
…
let addCardView = STPAddCardViewController()
addCardView.delegate = self
// Start the addCardView
self.navigationController.pushViewController(addCardView, animated: true)
}
…
func addCardViewController(_ addCardViewController: STPAddCardViewController, didCreatePaymentMethod paymentMethod: STPPaymentMethod, completion: #escaping STPErrorBlock) {
// TODO: do something with paymentMethod
// Always call completion() to dismiss the view
completion()
}
func addCardViewControllerDidCancel(_ addCardViewController: STPAddCardViewController) {
// TODO: handle cancel
}
}
But rather than my partial example I'd recommend reading these docs and trying out this example iOS code. Best wishes!
I am writing a macOS application with Swift using story boards. I have a NSTableView which contains files that I want the user to be able to preview via QuickLook.
I seemingly have everything in place and my code looks very similar to what has been described here: QuickLook consumer as a delegate from an NSViewController, but I keep getting the error
-[QLPreviewPanel setDataSource:] called while the panel has no controller - Fix this or this will raise soon.
See comments in QLPreviewPanel.h for -acceptsPreviewPanelControl:/-beginPreviewPanelControl:/-endPreviewPanelControl:.
I've been trying to adapt the solution of above post to my situation with Swift and story boards.
The main pieces are:
import Quartz
class ViewController: NSViewController, QLPreviewPanelDataSource, QLPreviewPanelDelegate {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
let windowNextResponder = self.view.window?.nextResponder
self.view.window?.nextResponder = self
self.nextResponder = windowNextResponder
}
// *** Quicklook stuff ***
#IBAction func quickLookButtonAction(_ sender: Any) {
guard qlPanel != nil else {
return
}
if qlPanel!.currentController == nil {
print ("No controller")
//qlPanel!.windowController = self.view.window?.windowController
// qlPanel!.updateController()
} else {
print (qlPanel!.currentController)
}
qlPanel!.delegate = self
qlPanel!.dataSource = self
qlPanel!.makeKeyAndOrderFront(self)
}
func numberOfPreviewItems(in panel: QLPreviewPanel!) -> Int {
return CSVarrayController.selectedObjects.count
}
func previewPanel(_ panel: QLPreviewPanel!, previewItemAt index: Int) -> QLPreviewItem! {
let file = CSVarrayController.selectedObjects[index] as! CSVfile
return file.url as NSURL
}
override func acceptsPreviewPanelControl(_ panel: QLPreviewPanel!) -> Bool {
return true
}
override func beginPreviewPanelControl(_ panel: QLPreviewPanel!) {
panel.dataSource = self
panel.delegate = self
}
override func endPreviewPanelControl(_ panel: QLPreviewPanel!) {
panel.dataSource = nil
panel.delegate = nil
}
}
With or without messing with the responder chain I get the error.
The delegate functions all get called as expected as well.
Remove
qlPanel!.delegate = self
qlPanel!.dataSource = self
in quickLookButtonAction, the viewcontroller isn't in control yet. Wait for beginPreviewPanelControl.
From the documentation for currentController:
You should never change the preview panel’s state (its delegate, datasource, and so on) if you are not controlling it.
From comments in QLPreviewPanel.h for -beginPreviewPanelControl::
Sent to the object taking control of the Preview Panel.
The receiver should setup the preview panel (data source, delegate, binding, etc.) here.
I have an NSSearchField inside a NSToolbar that I am attempting to set makeFirstResponder on but it is working intermittently. At times the NSSearchField will become the first responder without the call to makeFirstResponder and makeFirstResponder is returning true as if it were set successfully. Setting NSWindow.initialFirstResponder has also failed to work.
class ViewController: NSViewController {
override func viewDidAppear() {
super.viewDidAppear()
view.window?.makeFirstResponder(view.window?.windowController?.searchField
}
}
I have had consistent working results by delaying the code with a timer but this is a less than ideal solution.
class ViewController: NSViewController {
override func viewDidAppear() {
super.viewDidAppear()
Timer.scheduledTimer(withTimeInterval: 1, repeats: false) { _ in
self.view.window?.makeFirstResponder(self.windowController?.searchField)
}
}
}
If makeFirstResponder is returning true, then the it likely was made the first responder for at least a short amount of time.
You can use the fact that NSWindow.firstResponder is KVO compliant in order to detect any changes to it with something like the following code in your ViewController class:
override func viewDidAppear() {
super.viewDidAppear()
self.view.window?.addObserver(self, forKeyPath: "firstResponder", options: [.initial, .new], context: nil)
self.view.window?.makeFirstResponder(self.windowController?.searchField)
}
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
if keyPath == "firstResponder" {
print("First responder of window: \(object) is \(change?[NSKeyValueChangeKey.newKey])")
}
}
I found a blog that led me to find the reason why this was happening. By default in macOS an NSWindow has an isRestorable Boolean value that will recall whatever the last firstResponder was regardless of what is set as an initialFirstResponder or what is set inside viewDidAppear, etc.
I found that calling webView.makeFirstResponder() didn't do anything.
But calling view.window?.makeFirstResponder(webView) did.
no idea why.
hours of frustration.
I've been debugging my code and found that my manager was deinitialised (that was cause of my bug - not calling delegate methods).
What's strange, that during debugging process I've used "po" command after setting the manager's delegate (weak) and it prevented it from being deinitialised (delegate methods were called).
Why is that? Is it proper behaviour?
Xcode 8.3, swift 3.1
EDIT:
//a tap starts everything :)
#IBAction func shareButtonPressed(_ sender: Any) {
let requestManager = FacebookPostRouteRequest() //bug fixed by changing to instance variable
requestManager.delegate = self
requestManager.showShareBadgeDialog(self.badge!, onViewController: self)
}
//in FacebookPostRouteRequest
final weak var delegate: FacebookPostRouteRequestDelegate?
func showShareBadgeDialog(_ badge: Badge, onViewController viewController: UIViewController) {
let dialog = self.initDialog(onViewController: viewController)
guard let imageURL = badge.imageURL else {
self.delegate?.facebookPostRouteRequest(self, didCompleteWithResult: false)
return
}
dialog.shareContent = self.generateImageShareContent(imageURL)
self.show(dialog)
}
private func show(_ dialog: FBSDKShareDialog) {
OperationQueue.main.addOperation {
dialog.delegate = self //when printed out dialog.delegate delegate methods were called! Deinit of FacebookPostRouteRequest is not called.
let showResult = dialog.show()
...
}
}
extension FacebookPostRouteRequest: FBSDKSharingDelegate {
func sharer(_ sharer: FBSDKSharing!, didCompleteWithResults results: [AnyHashable : Any]!) {
...
}
//other delegate methods implemented as well
}
Your problem is here:
#IBAction func shareButtonPressed(_ sender: Any) {
let requestManager = FacebookPostRouteRequest()
requestManager.delegate = self
requestManager.showShareBadgeDialog(self.badge!, onViewController: self)
}
After the last line, the requestManager object will be disposed because it's no longer referenced and will not call any of the delegate methods.
Make requestManager an instance variable:
let requestManager = FacebookPostRouteRequest()
#IBAction func shareButtonPressed(_ sender: Any) {
requestManager.delegate = self
requestManager.showShareBadgeDialog(self.badge!, onViewController: self)
}
Your issues with the debugger are probably race conditions for stopping the main thread.