The touchbar-specific NSScrubber control scrolls with inertia on a pan gesture. I want to be notified of this animation's end to perform some function.
Try 1
The NSScrubberDelegate has a - didFinishInteractingWithScrubber: method which I implemented. However, soon after I stop manipulating the scrubber directly -- lifts the finger off the touchbar -- I get a callback, but the scroll continues to happen due to inertia. The final item that gets selected is NOT the one when this delegate method was called back.
Try 2
Digging further, I came across NSAnimation. Though it isn't documented clearly, I gather that scrubber is also a NSAnimatablePropertyContainer, as its selectedIndex property documentation says one can animate the selection through the animator proxy thus: scrubber.animator.selectedIndex = i. By that virtue, assuming that the animated property for the smooth panning is the boundsOrigin, I tried querying it.
I was able to get a CAAnimation by doing this
CAAnimation* a = [NSScrubber defaultAnimationForKey:#"boundsOrigin"];
// returns the same pointer value as above
// a = [myScrubber animationForKey:#"boundsOrigin"];
a.delegate = self;
...
- (void)animationDidStop:(CAAnimation *)anim
finished:(BOOL)flag {
if (flag == YES)
NSLog(#"Animation ended!\n");
}
I get a valid pointer value for a. However, I get numerous calls to animationDidStop with all of them having flag = YES; as the scrubber scrolls I keep getting these calls and when the scroll stops the calls stop. This feels closest to what I want but I dunno why so many calls come instead of just one when the animation ends.
Since NSScrubber's NSView or NSScrollView aren't exposed, I'm not sure if I'm querying the right object to get to the right NSAnimation.
Try 3
I also tried the hacky route of doing this on manipulation end code in vain
-(void)didFinishInteractingWithScrubber:(NSScrubber *)scrubber {
NSLog(#"Manipulation ended\n");
NSAnimationContext*c = NSAnimationContext.currentContext;
[c setCompletionHandler:^{
NSLog(#"Inertial scrolling stopped!\n");
}];
}
The completion handler is called almost immediately, before the inertial scroll stops :(
Ask
Is there anyway to know when the scrubber's pan gesture inertial animation ends?
I finally found a way to register a callback for the pan gesture's inertial scroll animation end.
Like any other scroll view, this also has the NSScrollViewDidEndLiveScrollNotification. Use the notification centre to register for the callback!
NSScrollView *sv = myScrubber.enclosingScrollView;
// register for NSScrollViewWillStartLiveScrollNotification if start is also needed
[[NSNotificationCenter defaultCenter] addObserverForName:NSScrollViewDidEndLiveScrollNotification
object:sv
queue:nil
usingBlock:^(NSNotification * _Nonnull note) {
NSLog(#"Scroll complete");
}];
Thanks to this answer for showing this approach.
I have a UIViewController that, depending on the frequency set by user, displays images in a animateWithDuration fade-in/fade-out every X seconds (say, 5 or 10). To manage the regularly timed calls to fade-in/out the images, I have a NSTimer that is set every time viewWillAppear is called.
Some function that does the animation, let's call it "showImageNow":
// on...
[UIView animateWithDuration:someInterval
delay:0
options:UIViewAnimationCurveEaseInOut
animations:
^{
// UI alpha = ... code here
}
// off...
completion:^(BOOL finished){
[UIView animateWithDuration:someOtherInterval
delay:yetAnotherValue
options:UIViewAnimationCurveEaseInOut
animations:
^{
// UI alpha = ... code here
}
completion:nil
];
}
];
In viewWillAppear:
if(myTimer != nil)
{
[myTimer invalidate]; // in case user changed the frequency in settings view
}
myTimer = [NSTimer scheduledTimerWithTimeInterval: [[NSUserDefaults standardUserDefaults] doubleForKey:#"userFrequency"]
target:self
selector: #selector(showImageNow:)
userInfo: nil
repeats: YES];
In viewDidAppear:
if(myTimer) { [myTimer fire]; }
While everything works as expected most of the time, the fade-out part of the first animation is cut off/stutters every time the UIViewController is re-appeared (from say, app went to background or app was in another view). The fade-in part of the animation works always, oddly enough. This is observed on a real device, not the simulator. So the fade-in/out works for every animation except the first one (the fade-out part doesn't work).
Notes:
Yes, I've tried [myTimer fire] in the viewWillAppear (instead of viewDidAppear) as well, but this causes other issues like the UIViewController's elements show up rather abruptly when user switches to that view from other views or from background mode.
The frequency is much longer than the animateWithDuration's animation values, so there shouldn't be any frame overlaps or whatever UI overlaps there may be.
I put debug code before every animateWithDuration call in the UIVIewController, so I know for certain that no other animateWithDuration is interrupting the very first image animateWithDuration call.
So this is perplexing. I've tried using CADisplayLink but apparently that's not the right way to do it. Any ideas how to resolve this issue?
I'd try enabling the UIViewAnimationOptionBeginFromCurrentState option in your animation code and see if that helps
I'm attempting to save a thumbnail of a mapview when a user taps save when an annotation has been selected. The problem occurs when the user has not zoomed in on that annotation yet, so the close zoom level has not been loaded.
This is what I'm doing after the user taps save:
Set a bool "saving" to true
Center and zoom in on the annotation (no animation)
When the mapViewDidFinishLoadingMap delegate method gets called, and if saving is true:
Create an UIImage out of the view, and save it. Dismiss modal view.
However when the image is saved, and the view is dismissed the result image saved actually has not finished loading, as I still see an unloaded map with gridlines as shown below:
My question is, how can I ensure the map is finished loading AND finished displaying before I save this thumbnail?
Update: iOS7 has a new delegate which may have fixed this problem. I have not confirmed one way or the other yet.
- (void)mapViewDidFinishRenderingMap:(MKMapView *)mapView fullyRendered:(BOOL)fullyRendered
Pre iOS6 support:
mapViewDidFinishLoadingMap: appears to be unreliable. I notice that it is sometimes not called at all, especially if the map tiles are already cached, and sometimes it is called multiple times.
I notice that when it is called multiple times the last call will render correctly. So I think you can get this to work if you set up a 2 second timer after the user taps save. Disable interactions so that nothing else can happen, and enable user interactions when the timer goes.
If mapViewDidFinishLoadingMap gets called reset the timer again for 2 seconds in the future. When the timer finally goes off, get the snapshot of the map and it should be correct.
You will also want to consider the other callbacks such as mapViewDidFailLoadingMap. Also test this on a noisy connection, since 2 seconds may not be long enough if it takes a long time to fetch the tiles.
- (void)restartTimer
{
[self.finishLoadingTimer invalidate];
self.finishLoadingTimer = [NSTimer scheduledTimerWithTimeInterval:2.0
target:self
selector:#selector(mapLoadingIsFinished)
userInfo:nil
repeats:NO];
}
- (void)userClickedSave
{
assert(self.saving == NO);
if (self.saving == NO) {
self.saving = YES;
assert(self.finishLoadingTimer == nil);
self.view.userInteractionEnabled = NO;
[self restartTimer];
}
}
- (void)mapLoadingIsFinished
{
self.finishLoadingTimer = nil;
[self doSnapshotSequence];
self.saving = NO;
self.view.userInteractionEnabled = YES;
}
- (void)mapViewDidFinishLoadingMap:(MKMapView *)mapView
{
if (self.saving) {
[self restartTimer];
}
}
If developing for iOS7 the best delegate to use is: mapViewDidFinishRenderingMap:fullyRendered:
mapViewDidFinishRenderingMap:fullyRendered
Are you sure the area where you are taking the screenshot has the Zoom Level supported which you are applying. For example, in US zoom level support is higher, you can zoom in to the maximum detail, while in Asia may be a high zoom level might not be supported.
I have a problem when putting my iPhone app to background by pushing the exit button, and then relaunching by tapping the launch icon on the home screen: the app's view does return to its initial state like I want it to, but before that it flashes the earlier, wrong view state onscreen briefly.
Background
My main view consists basically of a sequence of interlinked UIAnimateWithDuration calls. The behavior I want whenever any interruption occurs, is to reset the animation to its initial state (unless the animations have all finished and the app has entered the static final phase), and start over from there whenever the app returns to active and visible state.
After studying the subject I learned I need two types of interruption handling code to provide good ux: "instant" and "smooth". I have the method resetAnimation that resets the view properties to the initial state instantly, and the method pauseAnimation that animates quickly to the same state, with an additional label stating "paused" fading in on the top of the view.
Double clicking exit button
The reason for this is the "double clicking exit button" use case, that actually does not hide your view or put you in the background state, it just scrolls up a bit to show the multitasking menu at the bottom. So, resetting the view state instantly in this case just looked very ugly. The animated transition and telling the user you're paused seemed like a better idea.
This case works nice and smootly by implementing the applicationWillResignActive delegate method in my App Delegate and calling pauseAnimation from there. I handle returning from that multitasking menu by implementing the applicationDidBecomeActive delegate method and calling from there my resumeAnimation method, that fades out the "paused" label if its there, and starts my animation sequence from the initial state.
This all works fine, no flickering anywhere.
Visiting flipside
My app's built over the Xcode "utility" template, so it has a flipside view to show info/settings. I handle visiting the flipside and returning back to the main view by implementing these two delegate methods in my main view controller:
(void)viewDidDisappear:(BOOL)animated
(void)viewDidAppear:(BOOL)animated
I call my resetAnimation in the viewDidDisappear method and resumeAnimation in viewDidAppear. This all works fine, the main view is its initial state from the very beginning of the transition to visible state - no unexpected flashing of wrong animation states of anything. But:
Pushing exit button and relaunching from my app icon (the buggy part!)
This is where the trouble starts. When I push exit button once and my app begins its transition to background, two things happen. First, applicationWillResignActive gets called here too, so my pauseAnimation method launches also. It wouldn't need to, since the transition doesn't need to be smooth here – the view just goes static, and "zooms out" to reveal the home screen – but what can you do? Well, it wouldn't do any harm either if I just could call resetAnimation before the exact moment that the system takes the snapshot of the view.
Anyways, secondly, applicationDidEnterBackground in the App Delegate gets called. I tried to call resetAnimation from there so that the view would be in the right state when the app returns, but this doesn't seem to work. It seems the "snapshot" has been taken already and so, when I tap my app launch icon and relauch, the wrong view state does flash briefly on the screen before the correct, initial state shows. After that, it works fine, the animations go about like they're supposed to, but that ugly flicker at that relaunch moment won't go away, no matter what I try.
Fundamentally, what I'm after is, what exact moment does the system take this snapshot? And consequently, what would be the correct delegate method or notification handler to prepare my view for taking the "souvenir photo"?
PS. Then there's the default.png, which doesn't seem to only show at first launch, but also whenever the processor's having a hard time or returning to the app is delayed briefly for some other reason. It's a bit ugly, especially if you're returning to your flipside view that looks totally different from your default view. But this is such a core iOS feature, I'm guessing I shouldn't even try to figure out or control that one :)
Edit: since people were asking for actual code, and my app has already been released after asking this question, I'll post some here. ( The app's called Sweetest Kid, and if you want to see how it actually works, it's here: http://itunes.apple.com/app/sweetest-kid/id476637106?mt=8 )
Here's my pauseAnimation method – resetAnimation is almost identical, except its animation call has zero duration and delay, and it doesn't show the 'Paused' label. One reason I'm using UIAnimation to reset the values instead of just assigning the new values is that for some reason, the animations just didn't stop if I didn't use UIAnimation. Anyway, here's the pauseAnimation method:
- (void)pauseAnimation {
if (currentAnimationPhase < 6 || currentAnimationPhase == 255) {
// 6 means finished, 255 is a short initial animation only showing at first launch
self.paused = YES;
[UIView animateWithDuration:0.3
delay:0
options:UIViewAnimationOptionAllowUserInteraction |
UIViewAnimationOptionBeginFromCurrentState |
UIViewAnimationOptionCurveEaseInOut |
UIViewAnimationOptionOverrideInheritedCurve |
UIViewAnimationOptionOverrideInheritedDuration
animations:^{
pausedView.alpha = 1.0;
cameraImageView.alpha = 0;
mirrorGlowView.alpha = 0;
infoButton.alpha = 1.0;
chantView.alpha = 0;
verseOneLabel.alpha = 1.0;
verseTwoLabel.alpha = 0;
verseThreeLabel.alpha = 0;
shine1View.alpha = stars1View.alpha = stars2View.alpha = 0;
shine1View.transform = CGAffineTransformIdentity;
stars1View.transform = CGAffineTransformIdentity;
stars2View.transform = CGAffineTransformIdentity;
finishedMenuView.alpha = 0;
preparingMagicView.alpha = 0;}
completion:^(BOOL finished){
pausedView.alpha = 1.0;
cameraImageView.alpha = 0;
mirrorGlowView.alpha = 0;
infoButton.alpha = 1.0;
chantView.alpha = 0;
verseOneLabel.alpha = 1.0;
verseTwoLabel.alpha = 0;
verseThreeLabel.alpha = 0;
shine1View.alpha = stars1View.alpha = stars2View.alpha = 0;
shine1View.transform = CGAffineTransformIdentity;
stars1View.transform = CGAffineTransformIdentity;
stars2View.transform = CGAffineTransformIdentity;
finishedMenuView.alpha = 0;
preparingMagicView.alpha = 0;
}];
askTheMirrorButton.enabled = YES;
againButton.enabled = NO;
shareOnFacebookButton.enabled = NO;
emailButton.enabled = NO;
saveButton.enabled = NO;
currentAnimationPhase = 0;
[[cameraImageView subviews] makeObjectsPerformSelector:#selector(removeFromSuperview)]; // To remove the video preview layer
}
}
The screenshot is taken immediately after this method returns. I guess your -resetAnimation method completes in the next runloop cycle and not immediately.
I've not tried this, but you could try to let the runloop run and then return a little bit later:
- (void) applicationDidEnterBackground:(UIApplication *)application {
// YOUR CODE HERE
// Let the runloop run for a brief moment
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:0.01]];
}
I hope this helps,
Fabian
Update: -pauseAnimation and -resetAnimation distinction
Approach: Delay the animation happening in -applicationWillResignActive: and cancel the delayed animation in -applicationDidEnterBackground:
- (void) applicationWillResignActive:(UIApplication *)application {
// Measure the time between -applicationWillResignActive: and -applicationDidEnterBackground first!
[self performSelector:#selector(pauseAnimation) withObject:nil afterDelay:0.1];
// OTHER CODE HERE
}
- (void) applicationDidEnterBackground:(UIApplication *)application {
[NSObject cancelPreviousPerformRequestsWithTarget:self selector:#selector(pauseAnimation) object:nil];
// OTHER CODE HERE
}
I've now run some tests, and eliminated the problem, thanks to #Fabian Kreiser.
To conclude: Kreiser had it right: iOS takes the screenshot immediately after the method applicationDidEnterBackground: returns -- immediately meaning, before the end of the current runloop.
What this means is, if you launch any scheduled tasks in the didEnterBackground method you want to finish before leaving, you will have to let the current runloop run for as long as the tasks might take to finish.
In my case, the scheduled task was an UIAnimateWithDuration method call -- I let myself be confused by the fact that both its delay and duration was 0 -- the call was nonetheless scheduled to run in another thread, and thus wasn't able to finish before the end of applicationDidEnterBackground method. Result: the screenshot was indeed taken before the display was updated to the state I wanted -- and, when relaunching, this screenshot flashed briefly onscreen, causing the unwanted flickering.
Furthermore, to provide the "smooth" vs. "instant" transition behavior explained in my question, Kreiser's suggestion to delay the "smooth" transition call in applicationWillResignActive: and cancel the call in applicationDidEnterBackground: works fine. I noticed the delay between the two delegate methods was around 0.005-0.019 seconds in my case, so I applied a generous margin and used a delay of 0.05 seconds.
My bounty, the correct answer tick, and my thanks go to Fabian. Hopefully this helps others in similar situation, too.
The runloop solution actually results in some problems with the app.
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:0.01]];
If you go to the background and immediately open the app again, the app will turn into a black screen. When you reopen the app for the second time, everything is back to normal.
A better way is to use
[CATransaction flush]
This forces all current transactions to be immediately applied and does not have the problem resulting in a black screen.
Depending on how hardcore important it is to you to have this transition run smoothly, you could kill off multi-tasking for your app entirely w/ UIApplicationExitsOnSuspend. Then, you would be guaranteed your Default.png and a clean visual state.
Of course, you'd have to save/restore state on exit/startup, and without more info on the nature of your app, it's tough to say whether this would be worth the trouble.
In iOS 7, there is [[UIApplication sharedApplication] ignoreSnapshotOnNextApplicationLaunch] call that does exactly what you needed.
I am trying to add a UIButton to the view of a MPMoviePlayerController along with the standard controls. The button appears over the video and works as expected receiving touch events, but I would like to have it fade in and out with the standard controls in response to user touches.
I know I could accomplish this by rolling my own custom player controls, but it seems silly since I am just trying to add one button.
EDIT
If you recursively traverse the view hierarchy of the MPMoviePlayerController's view eventually you will come to a view class called MPInlineVideoOverlay. You can add any additional controls easily to this view to achieve the auto fade in/out behavior.
There are a few gotchas though, it can sometimes take awhile (up to a second in my experience) after you have created the MPMoviePlayerController and added it to a view before it has initialized fully and created it's MPInlineVideoOverlay layer. Because of this I had to create an instance variable called controlView in the code below because sometimes it doesn't exist when this code runs. This is why I have the last bit of code where the function calls itself again in 0.1 seconds if it isn't found. I couldn't notice any delay in the button appearing on my interface despite this delay.
-(void)setupAdditionalControls {
//Call after you have initialized your MPMoviePlayerController (probably viewDidLoad)
controlView = nil;
[self recursiveViewTraversal:movie.view counter:0];
//check to see if we found it, if we didn't we need to do it again in 0.1 seconds
if(controlView) {
UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];
[controlView addSubview:backButton];
} else {
[self performSelector:#selector(setupAdditionalControls) withObject:nil afterDelay:0.1];
}
}
-(void)recursiveViewTraversal:(UIView*)view counter:(int)counter {
NSLog(#"Depth %d - %#", counter, view); //For debug
if([view isKindOfClass:NSClassFromString(#"MPInlineVideoOverlay")]) {
//Add any additional controls you want to have fade with the standard controls here
controlView = view;
} else {
for(UIView *child in [view subviews]) {
[self recursiveViewTraversal:child counter:counter+1];
}
}
}
It isn't the best solution, but I am posting it in case someone else is trying to do the same thing. If Apple was to change the view structure or class names internal to the control overlay it would break. I am also assuming you aren't playing the video full screen (although you can play it fullscreen with embeded controls). I also had to disable the fullscreen button using the technique described here because the MPInlineVideoOverlay view gets removed and released when it is pressed: iPad MPMoviePlayerController - Disable Fullscreen
Calling setupAdditionalControls when you receive the fullscreen notifications described above will re-add your additional controls to the UI.
Would love a more elegant solution if anyone can suggest something other than this hackery I have come up with.
My solution to the same problem was:
Add the button as a child of the MPMoviePlayerController's view;
fade the button in and out using animation of its alpha property, with the proper durations;
handle the player controller's touchesBegan, and use that to toggle the button's visibility (using its alpha);
use a timer to determine when to hide the button again.
By trial-and-error, I determined that the durations that matched the (current) iOS ones are:
fade in: 0.1s
fade out: 0.2s
duration on screen: 5.0s (extend that each time the view is touched)
Of course this is still fragile; if the built-in delays change, mine will look wrong, but the code will still run.