CODEWITHSUNDEEP
objective-cnstimeranimatewithduration
Uzumaki Naruto
Uzumaki Naruto

Reputation: 547

Repeating NSTimer causes truncated animateWithDuration on first animation

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:

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?

Upvotes: 0

Views: 263

Answers (1)

Nick
Nick

Reputation: 2369

I'd try enabling the UIViewAnimationOptionBeginFromCurrentState option in your animation code and see if that helps

Upvotes: 1

Related Questions