My issue is that I am getting local notifications and then telling one of my VCs to updates its UITableView. However, the tableview doesn't reload. I know for a fact that all the if statement checks are passing and it is running the code. This originally made me believe it was a thread issue so I wrapped the reload in dispatch_async(dispatch_get_main_queue(), {}). This however doesn't work either. So if it is not a thread issues what is it? What could be causing this? Am I doing something wrong here?
func application(application: UIApplication, didReceiveLocalNotification notification: UILocalNotification) {
if notification.alertBody != nil{
if notification.alertBody!.hasSuffix("starting") || notification.alertBody!.hasSuffix("ending"){
dispatch_async(dispatch_get_main_queue(), {
if topMostContoller() is SecondViewController{
let vc = self.tabBarController?.getVC(.Attendance) as! SecondViewController
vc.myTableView?.reloadRowsAtIndexPaths((vc.myTableView?.indexPathsForVisibleRows)!, withRowAnimation: .None)
// vc.myTableView?.reloadData() <- this doesn't work either
}
})
}
}
}
Edit:
func getVC(vc:tabBarVC)->UIViewController?{
switch vc{
case .Home:
return fullTabBar[0]
case .Attendance:
return fullTabBar[1]
case .Location:
return fullTabBar[2]
case .Sign:
return fullTabBar[3]
case .Settings:
return fullTabBar[4]
}
}
Where fullTabBar is set in the tabBar's viewDidLoad.
fullTabBar = self.viewControllers as [UIViewController]!
self being the tabBar instance.
I unfortunately can't see anything wrong with your code, logically it should be working. Possibly your data source is being updated after reloadData is being called, although considering the cleanliness of your code I doubt that is the case.
I would try the following pattern, if only to see if the code in your answer is in fact faulty.
In SecondViewController's viewDidLoad:
NSNotificationCenter.defaultCenter().addObserver(self, selector: "reloadTableView:", name: "reloadSecondVCTableView", object: nil)
And in the body:
func reloadTableView(_: NSNotification) {
tableView.reloadData()
}
And after the second if statement in your posted code send the notification :
NSNotificationCenter.defaultCenter().postNotificationName("reloadSecondVCTableView", object: nil)
Related
I have a music app and I wish to determine if playback has been paused while the app was closed (due to an event like a phone call or AirPods being taken out of ear etc)
My first approach was to run a func inside of viewWillAppear that checked
if mediaPlayer.playbackState == .paused {
...
}
If it was paused I updated the play/pause button image. However, this did not work, the play/pause button would still show Play even if it was paused.
Next, I tried adding an observer to the viewDidLoad
NotificationCenter.default.addObserver(self, selector: #selector(self.wasSongInterupted(_:)), name: UIApplication.didBecomeActiveNotification, object: self.mediaPlayer)
The self.wasSongInterupted I call is
#objc func wasSongInterupted(_ notification: Notification) {
DispatchQueue.main.async {
if self.mediaPlayer.playbackState == .paused {
print("paused")
self.isPlaying = false
self.playPauseSongButton.isSelected = self.isPlaying
} else if self.mediaPlayer.playbackState == .playing {
self.isPlaying = true
self.playPauseSongButton.isSelected = self.isPlaying
}
}
}
However, I am still having the same issue.
What is the best way to determine if my music player is playing or paused when I reopen the app?
Edit 1: I Edited my code based on comments.
wasSongInterrupted was not being called, and through breakpoints and errors I discovered the code was mostly not needed. I changed my code to be
func wasSongInterrupted() {
DispatchQueue.main.async {
if self.mediaPlayer.playbackState == .interrupted {
var isPlaying: Bool { return self.mediaPlayer.playbackState == .playing }
print("Playback state is \(self.mediaPlayer.playbackState.rawValue), self.isPlaying Bool is \(self.isPlaying)")
self.playPauseSongButton.setImage(UIImage(named: "playIconLight"), for: .normal)
//self.playPauseSongButton.isSelected = self.isPlaying
}
}
}
and inside my AppDelegate's applicationDidBecomeActive I have
let mediaPlayerVC = MediaPlayerViewController()
mediaPlayerVC.wasSongInterupted()
Now the code runs, however I have an issue.
If I run the following code:
if self.mediaPlayer.playbackState == .interrupted {
print("interrupted \(self.isPlaying)")
}
and then make a call and come back to the app it will hit the breakpoint. It will print out interrupted as well as false which is the Bool value for self.isPlaying
However if I try to update the UI by
self.playPauseSongButton.isSelected = self.isPlaying
or by
self.playPauseSongButton.setImage(UIImage(named: "playIconLight.png"), for: .normal)
I get an error message Thread 1: EXC_BREAKPOINT (code=1, subcode=0x104af9258)
You trying to update you player UI from viewWillAppear. From Apple Documentation:
viewWillAppear(_:)
This method is called before the view controller's view is about to be added to a view hierarchy and before any animations are configured for showing the view.
So if your app was suspended and the becomes active again, this method won't be called, because your UIViewController is already at Navigations Stack.
If you want to catch the moment when your app becomes active from suspended state, you need to use AppDelegate. From Apple Documentation:
applicationDidBecomeActive(_:)
This method is called to let your app know that it moved from the inactive to active state. This can occur because your app was launched by the user or the system.
So you need to use this method at your AppDelegate to handle app running and update your interface.
UPDATE
You saying the inside this AppDelegate method you're doing
let mediaPlayerVC = MediaPlayerViewController()
mediaPlayerVC.wasSongInterupted()
That's wrong because you're creating a new view controller. What you need to do, is to access you existing view controller from navigation stack and update it.
One of the possible solutions is to use NotificationCenter to send a notification. You view controller should be subscribed to this event of course.
At first, you need to create a notification name
extension Notification.Name {
static let appBecameActive = Notification.Name(rawValue: "appBecameActive")
}
Then in you AppDelegate add following code to post your notifications when app becomes active
func applicationDidBecomeActive(_ application: UIApplication) {
NotificationCenter.default.post(name: .appBecameActive, object: nil)
}
And finally in your view controller add to subscribe it on notifications
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default.addObserver(self,
selector: #selector(wakeUp),
name: .appBecameActive,
object: nil)
...
}
#objc func wakeUp() {
// Update your UI from here
}
Hope it helps you.
I trying to make a calling app for my project and I want to add a function that keeps checking if someone if calling. My app uses Firebase where I have a key for each users to check if he made a call or not.
There's two problem I am facing here, the first one is, as I said, that I want my function to keep checking anywhere in the app for an incoming call. The other problem is that i have a viewcontroller that I want to pop up when someone is calling. I have found this code on github but it uses navigationcontroller which I am not using in my app :
extension UIViewController{
func presentViewControllerFromVisibleViewController(viewControllerToPresent: UIViewController, animated flag: Bool, completion: (() -> Void)? = nil) {
if let navigationController = self as? UINavigationController, let topViewController = navigationController.topViewController {
topViewController.presentViewControllerFromVisibleViewController(viewControllerToPresent: viewControllerToPresent, animated: true, completion: completion)
} else if (presentedViewController != nil) {
presentedViewController!.presentViewControllerFromVisibleViewController(viewControllerToPresent: viewControllerToPresent, animated: true, completion: completion)
} else {
present(viewControllerToPresent, animated: true, completion: completion)
}
}
}
For your question on monitoring when incoming calls occur and to be called as a result, see this answer. It's probably what you need (I've never tried it, however). The example shows creating a CXCallObserver and setting your AppDelegate as delegate.
For your second question, I'd first try this answer which leverages the window.rootViewController so you can do this from your AppDelegate. Generally, the root VC is your friend when trying to do UI your AppDelegate. :)
A better answer based on Alex's added comments:
I'd first look at how to set up an observer to your Firebase model so that you can get a callback. If you don't have a way to do that, I'd use KVO on the Firebase model property. But to do exactly as you're requesting, and to do so lazily from AppDelegate (rather than from a singleton), see this code:
// In AppDelegate
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey : Any]? = nil) -> Bool
{
self.timerToCheckForCalls = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(timerFired), userInfo: nil, repeats: true)
}
func timerFired()
{
let didCall = // TODO: query your Firebase model...
guard didCall == true else
{
return
}
self.displayCallerView()
}
func displayCallerView()
{
// See below link.
}
See this answer for how to present your view controller, even when your app might be showing an action sheet, alert, etc... which I think you'd especially value since you need to display the caller regardless of what your app is doing.
Note while user is scrolling a UITextView, the timer won't fire yet. There may be other situations where the timer could be delayed too. So it really would be best to observe your Firebase model or receive a KVO callback than to use a timer.
If you want to make a function that can be called from anywhere, use a singleton pattern. You can also use that to store your special view controller.
Bear in mind that this code SHOULD NOT considered fully functioning code and will need to be customized by you to suit your needs.
class MyClass {
let shared = MyClass()
var viewController: SpecialViewController?
func checkForCall() {
// do function stuff
}
func getSpecialViewController() {
let storyBoard = UIStoryboard.init(name: "main", bundle: nil)
// keep it so we don't have to instantiate it every time
if viewController == nil {
viewController = storyBoard.instantiateViewController(withIdentifier: "SomeViewController")
}
return viewController
}
}
// Make an extension for UIViewController so that they can all
// use this function
extension UIViewController {
func presentSpecialViewController() {
let vc = MyClass.shared.getSpecialViewController()
present(vc, animated: false, completion: nil)
}
}
Somewhere in your code:
// in some function
MyClass.shared.checkForCall()
Somewhere else in code:
presentSpecialViewController()
I'm working on implementing screen-capturing of a Mac app suing CGDisplayStream, similar to the question asked here, but in Swift.
Below is the code I have in my app's single ViewController:
override func viewDidAppear() {
super.viewDidAppear()
let backgroundQueue = DispatchQueue(label: "com.app.queue",
qos: .background,
target: nil)
let displayStream = CGDisplayStream(dispatchQueueDisplay: 0, outputWidth: 100, outputHeight: 100,pixelFormat: Int32(k32BGRAPixelFormat), properties: nil, queue: backgroundQueue) { (status, code, iosurface, update) in
switch(status){
case .frameBlank:
print("FrameBlank")
break;
case .frameIdle:
print("FrameIdle")
break;
case .frameComplete:
print("FrameComplete")
break;
case .stopped:
print("Stopped")
break;
}
self.update()
}
displayStream?.start()
}
func update(){
print("WORKING")
}
What seems to be happening is that the queue process isn't being properly initialized, but I'm not sure...when the app starts, the self.update() is called once, but only once. Given that the display stream has started properly, I would expect this function to be called repeatedly, but it's only called once.
Anyone have any ideas? Am I not setting up a queue properly?
Thank you!
The problem is that no reference to displayStream is kept outside
of viewDidAppear, so the stream will be deallocated on return
of that method.
Making it a property of the view controller should solve the problem:
class ViewController: NSViewController {
var displayStream: CGDisplayStream?
override func viewDidAppear() {
super.viewDidAppear()
// ...
displayStream = CGDisplayStream(...)
displayStream?.start()
}
override func viewWillDisappear() {
super.viewWillDisappear()
displayStream?.stop()
displayStream = nil
}
}
Releasing the stream in viewWillDisappear breaks the retain cycle
and allows the view controller to be deallocated (if it is part of
a view controller hierarchy).
You have a vc (green) and it has a panel (yellow) "holder"
Say you have ten different view controllers...Prices, Sales, Stock, Trucks, Drivers, Palettes, which you are going to put in the yellow area, one at a time. It will dynamically load each VC from storyboard
instantiateViewController(withIdentifier: "PricesID") as! Prices
We will hold the current VC one in current. Here's code that will allow you to "swap between" them...
>>NOTE, THIS IS WRONG. DON'T USE THIS CODE<<
One has to do what Sulthan explains below.
var current: UIViewController? = nil {
willSet {
// recall that the property name ("current") means the "old" one in willSet
if (current != nil) {
current!.willMove(toParentViewController: nil)
current!.view.removeFromSuperview()
current!.removeFromParentViewController()
// "!! point X !!"
}
}
didSet {
// recall that the property name ("current") means the "new" one in didSet
if (current != nil) {
current!.willMove(toParentViewController: self)
holder.addSubview(current!.view)
current!.view.bindEdgesToSuperview()
current!.didMove(toParentViewController: self)
}
}
}
>>>>>>>>IMPORTANT!<<<<<<<<<
Also note, if you do something like this, it is ESSENTIAL to get rid of the yellow view controller when the green page is done. Otherwise current will retain it and the green page will never be released:
override func dismiss(animated flag: Bool, completion: (() -> Void)? = nil) {
current = nil
super.dismiss(animated: flag, completion: completion)
}
Continuing, you'd use the current property like this:
func showPrices() {
current = s.instantiateViewController(withIdentifier: "PricesID") as! Prices
}
func showSales() {
current = s.instantiateViewController(withIdentifier: "SalesID") as! Sales
}
But consider this, notice "point X". Normally there you'd be sure to set the view controller you are getting rid of to nil.
blah this, blah that
blah.removeFromParentViewController()
blah = nil
However I (don't think) you can really set current to nil inside the "willSet" code block. And I appreciate it's just about to be set to something (in didSet). But it seems a bit strange. What's missing? Can you even do this sort of thing in a computed property?
Final usable version.....
Using Sulthan's approach, this then works perfectly after considerable testing.
So calling like this
// change yellow area to "Prices"
current = s.instantiateViewController(withIdentifier: "PricesID") as! Prices
// change yellow area to "Stock"
current = s.instantiateViewController(withIdentifier: "StickID") as! Stock
this works well...
var current: UIViewController? = nil { // ESSENTIAL to nil on dismiss
didSet {
guard current != oldValue else { return }
oldValue?.willMove(toParentViewController: nil)
if (current != nil) {
addChildViewController(current!)
holder.addSubview(current!.view)
current!.view.bindEdgesToSuperview()
}
oldValue?.view.removeFromSuperview()
oldValue?.removeFromParentViewController()
if (current != nil) {
current!.didMove(toParentViewController: self)
}
}
// courtesy http://stackoverflow.com/a/41900263/294884
}
override func dismiss(animated flag: Bool, completion: (() -> Void)? = nil) {
// ESSENTIAL to nil on dismiss
current = nil
super.dismiss(animated: flag, completion: completion)
}
Let's divide the question into two: (1) Is there a "leak"? and (2) Is this a good idea?
First the "leak". Short answer: no. Even if you don't set current to nil, the view controller it holds obviously doesn't "leak"; when the containing view controller goes out of existence, so does the view controller pointed to by current.
The current view controller does, however, live longer than it needs to. For that reason, this seems a silly thing to do. There is no need for a strong reference current to the child view controller, because it is, after all, your childViewControllers[0] (if you do the child view controller "dance" correctly). You are thus merely duplicating, with your property, what the childViewControllers property already does.
So that brings us to the second question: is what you are doing a good idea? No. I see where you're coming from — you'd like to encapsulate the "dance" for child view controllers. But you are doing the dance incorrectly in any case; you're thus subverting the view controller hierarchy. To encapsulate the "dance", I would say you are much better off doing the dance correctly and supplying functions that perform it, along with a computed read-only property that refers to childViewController[0] if it exists.
Here, I assume we will only ever have one child view controller at a time; I think this does much better the thing you are trying to do:
var current : UIViewController? {
if self.childViewControllers.count > 0 {
return self.childViewControllers[0]
}
return nil
}
func removeChild() {
if let vc = self.current {
vc.willMove(toParentViewController: nil)
vc.view.removeFromSuperview()
vc.removeFromParentViewController()
}
}
func createChild(_ vc:UIViewController) {
self.removeChild() // There Can Be Only One
self.addChildViewController(vc) // *
// ... get vc's view into the interface ...
vc.didMove(toParentViewController: self)
}
I don't think that using didSet is actually wrong. However, the biggest problem is that you are trying to split the code between willSet and didSet because that's not needed at all. You can always use oldValue in didSet:
var current: UIViewController? = nil {
didSet {
guard current != oldValue else {
return
}
oldValue?.willMove(toParentViewController: nil)
if let current = current {
self.addChildViewController(current)
}
//... add current.view to the view hierarchy here...
oldValue?.view.removeFromSuperview()
oldValue?.removeFromParentViewController()
current?.didMove(toParentViewController: self)
}
}
By the way, the order in which the functions are called is important. Therefore I don't advise to split the functionality into remove and add. Otherwise the order of viewDidDisappear and viewDidAppear for both controllers can be surprising.
I am trying to display an activity indicator whilst some text recognition happens. If i just start and stop[ the indicator around the recognition code it never shows. The issue i have is that if use:
activityIndicator.startAnimating()
DispatchQueue.main.async( execute: {
self.performTextRecognition()
})
activityIndicator.stopAnimating()
self.performSegue(withIdentifier: "segueToMyBills", sender: self)
The indicator never shows as it performs the segue and the table view in the next view controller shows no information because the text recognition hasn't completed. I've never touched on threads until now so a little insight on what to do would be much appreciated. Thanks!
Well your problem is that your OCR happens on the main thread. That blocks the thread thus never having time to draw the activity indicator. Try to modify your code into this:
activityIndicator.startAnimating()
DispatchQueue.global(qos: .background).async { [weak weaKSelf = self] in
// Use a weak reference to self here to make sure no retain cycle is created
weakSelf?.performTextRecognition()
DispatchQueue.main.async {
// Make sure weakSelf is still around
guard let weakSelf = weakSelf else { return }
weakSelf.activityIndicator.stopAnimating()
weakSelf.performSegue(withIdentifier: "segueToMyBills", sender: weakSelf)
}
}
Try to add a completion handler to your self.performTextRecognition() function in this way
function performTextRecognition(completion: ((Error?) -> Void)? = .none) {
//you can replace Error with Any type or leave it nil
//do your logic here
completion?(error)
}
and then call the function like this :
performTextRecognition(completion: { error in
activityIndicator.stopAnimating()
self.performSegue(withIdentifier: "segueToMyBills", sender: self)
})