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POHow to stop an NSTimer that I don't know is released or not
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copied!<p>Sorry to ask this question, but it's now day 3 I try to solve this problem and have no progress so far.</p> <p>The problem is this: during a game there is a pause between the user answered a question and the next question. Also in several other cases there are such pauses in gameplay. For this I use one NSTimer.</p> <p>In .h I have:</p> <pre><code>@property(nonatomic,retain) NSTimer *scheduleTimer; </code></pre> <p>and in the .m</p> <pre><code>@synthesize scheduleTimer; scheduleTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target: self selector: @selector(playFeedbackSound) userInfo: nil repeats: NO]; </code></pre> <p>now this works just fine. But when the user exits the ViewController I need to invalidate the timer. Otherwise the timer will fire and then crash the app or pops up stuff that does not belong in the other view etc.</p> <p>Therefore I write:</p> <pre><code>- (void)viewWillDisappear:(BOOL)animated { [scheduleTimer invalidate]; } </code></pre> <p>now this does the job if the timer is actually set. But if there is no such timer scheduled, the app just crashes. </p> <p>I tried probably everything there is, including @try (which crashes the app too, Zombie says "<em>*</em> -[CFRunLoopTimer invalidate]: message sent to deallocated instance 0x567640"). Since the timer gets released after it is done, a [scheduleTimer isValid] will just crash the app as well.</p> <p>Now I'm already pretty desperate, and as a last resort I'm thinking of replacing the timer with UIView animateWithDuration that does nothing visible.</p> <p>However, I think this should be a pretty standard situation. I just don't know why I can't find an answer to this very obvious task. Can you help? Thank you</p>

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