CODEWITHSUNDEEP
iosobjective-ccabasicanimation
SanitLee
SanitLee

Reputation: 1253

Core Animation stops animation on app re-appearance

I have created animation to my menu using CABasicAnimation. Here below is my code relevant to this issue:

- (void) viewDidLoad {
  ...
  [self setAwesomeMenu];
}

- (void)setAwesomeMenu {
  ...
  //set tag for awesomemenu subview
  [menu setTag:awesomeMenuSubViewTag];

  [self addPulseFilterSubView];
}

- (void) addPulseFilterSubView {
// add pulseEffectFilter subview
  UIImageView *pulseEffectFilter = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"pulse.png"]];
  [self.view insertSubview:pulseEffectFilter belowSubview:[self.view viewWithTag:awesomeMenuSubViewTag]];

  pulseEffectFilter.center = CGPointMake(160.0, 205.0);

  CABasicAnimation *theAnimation;
  theAnimation=[CABasicAnimation animationWithKeyPath:@"transform.scale"];
  theAnimation.duration=2.0;
  theAnimation.repeatCount=HUGE_VALL;
  //theAnimation.autoreverses=YES;
  theAnimation.fromValue=[NSNumber numberWithFloat:0.0];
  theAnimation.toValue=[NSNumber numberWithFloat:1.3];
  [pulseEffectFilter.layer addAnimation:theAnimation forKey:@"transform.scale"];
  theAnimation.removedOnCompletion = NO; // doesn't help

  CABasicAnimation *fadeOutAnimation;
  fadeOutAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
  fadeOutAnimation.fromValue = [NSNumber numberWithFloat:1.2];
  fadeOutAnimation.toValue = [NSNumber numberWithFloat:0.0];
  fadeOutAnimation.duration = 1.0;
  fadeOutAnimation.repeatCount=HUGE_VALL;
  [pulseEffectFilter.layer addAnimation:fadeOutAnimation forKey:@"opacity"];
  //fadeOutAnimation.autoreverses = YES;
  fadeOutAnimation.removedOnCompletion = NO; //doesn't help

  [pulseEffectFilter setTag:pulseEffectFilterSubViewTag];
}

When I call this view first time the animation works just fine. When this app is re-appeared from phone suspension the animation also works fine. But when I switch to another app or in the other word leave this app, then re-enter this app the animation is frozen. I found one article talking about this. They claimed it could be solved by setting a flag on the CABasicAnimation class called removedOnCompletion to NO. Unfortunately in my case it does not work. Does anyone know a solution to that? Thanks in advance.

Upvotes: 2

Views: 645

Answers (1)

GuybrushThreepwood
GuybrushThreepwood

Reputation: 5616

Ok I've tested your code and found a fix. In your app delegate add the following :

- (void)applicationDidBecomeActive:(UIApplication *)application {
    [[NSNotificationCenter defaultCenter] postNotificationName:@"resumeAnimation" object:nil];
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}

Then add a bool to track if the animation is on and register the notification (in your view class) : 

BOOL animationActive = NO;

@interface ViewController ()

@end

@implementation ViewController

- (void) viewDidLoad {

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(addPulseFilterSubView) name:@"resumeAnimation" object:nil];

    [self setAwesomeMenu];
}

Then at the start of addPulseFilterSubView check if we need to stop the previous animation : 

- (void) addPulseFilterSubView {

    if (animationActive) {
        for (UIView * view in self.view.subviews) {
            if (view.tag ==pulseEffectFilterSubViewTag) {
                [view removeFromSuperview];
            }
        }
    }
    // add pulseEffectFilter subview
    UIImageView *pulseEffectFilter = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"pulse.png"]];
    [self.view insertSubview:pulseEffectFilter belowSubview:[self.view viewWithTag:awesomeMenuSubViewTag]];
...

Then at the very end of this method : 

    animationActive = YES;
}

And all should be good :D

Upvotes: 1

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