iOS - NSTimer - SIGABRT after invalidate - Edit Now DeAlloc Msg - iphone

Question

I have my NSTimer embedded in a class that plays image sequences. Basically it loops and changes a UIImageView. Everything goes well if I let the image sequence finish but... on it's own if I try to stop the timer while it is playing I get a sigabrt. Edit: No longer a sigabrt but now a DeAlloc I can't explain.
The "stop" at the end of a frame sequence is the same stop I am calling mid sequence.
So what might cause an NSTimer to break mid function and DeAlloc. More to the point what might I look at to fix it.
Thanks.
I am using some example code from here: http://www.modejong.com/iOS/PNGAnimatorDemo.zip
Edit: I'll add what I believe to be the pertinent code here.
// Invoke this method to start the animation
- (void) startAnimating
{
self.animationTimer = [NSTimer timerWithTimeInterval: animationFrameDuration target: self selector: #selector(animationTimerCallback:) userInfo: NULL repeats: TRUE];
[[NSRunLoop currentRunLoop] addTimer: animationTimer forMode: NSDefaultRunLoopMode];
animationStep = 0;
if (avAudioPlayer != nil)
[avAudioPlayer play];
// Send notification to object(s) that regestered interest in a start action
[[NSNotificationCenter defaultCenter]
postNotificationName:ImageAnimatorDidStartNotification
object:self];
}
- (void) animationTimerCallback: (NSTimer *)timer {
if (![self isAnimating])
return;
NSTimeInterval currentTime;
NSUInteger frameNow;
if (avAudioPlayer == nil) {
self.animationStep += 1;
// currentTime = animationStep * animationFrameDuration;
frameNow = animationStep;
} else {
currentTime = avAudioPlayer.currentTime;
frameNow = (NSInteger) (currentTime / animationFrameDuration);
}
// Limit the range of frameNow to [0, SIZE-1]
if (frameNow < 0) {
frameNow = 0;
} else if (frameNow >= animationNumFrames) {
frameNow = animationNumFrames - 1;
}
[self animationShowFrame: frameNow];
// animationStep = frameNow + 1;
if (animationStep >= animationNumFrames) {
[self stopAnimating];
// Continue to loop animation until loop counter reaches 0
if (animationRepeatCount > 0) {
self.animationRepeatCount = animationRepeatCount - 1;
[self startAnimating];
}
}
}
- (void) stopAnimating
{
if (![self isAnimating])
return;
[animationTimer invalidate];
self.animationTimer = nil;
animationStep = animationNumFrames - 1;
[self animationShowFrame: animationStep];
if (avAudioPlayer != nil) {
[avAudioPlayer stop];
avAudioPlayer.currentTime = 0.0;
self->lastReportedTime = 0.0;
}
// Send notification to object(s) that regestered interest in a stop action
[[NSNotificationCenter defaultCenter]
postNotificationName:ImageAnimatorDidStopNotification
object:self];
}
Edit2: So I commented out an NSAssert in DeAlloc, commenting that out shed a bit more light. Now getting to self.animationTimer = nil; and saying *** -ImageAnimator setAnimationTimer:]: Message sent to deallocated instance.
DeAlloc is being called right when I invalidate the timer... so I'm a bit confused here.

Answer 1

I have a solution which is working but not optimal.
I just added another function to set the frame it's on to the last frame and it ends the sequence as I need.
But it doesn't solve the question of why it's doing it's crashing if I try to stop the sequence mid run.

Answer 2

Well, I wrote this code so I can assure you that it should be working just fine :) You need to invoke stopAnimating before you are done with the view, the only way you would have got the assert in dealloc is if the view was deallocated while it was still animating. That should not happen, which is exactly why there way an assert there. There is also a big comment explaining the assert, what is unclear about that?
- (void)dealloc {
// This object can't be deallocated while animating, this could
// only happen if user code incorrectly dropped the last ref.
NSAssert([self isAnimating] == FALSE, #"dealloc while still animating");
self.animationURLs = nil;
self.imageView = nil;
self.animationData = nil;
self.animationTimer = nil;
[super dealloc];
}
Just call:
[view stopAnimating];
Before you remove the view from its superview and everything will be just fine.