esanits esanits - 3 months ago 24
Objective-C Question

NSTimer crashes, when I call [Timer isValid] or [Timer invalidate]

I have two NSTimers in my iPhone app.
DecreaseTimer works fine, but TimerCountSeconds crashes when I call [timerCountSeconds isValid] or [timerCountSeconds invalidate]. They are used like this:

-(id)initialize { //Gets called, when the app launches and when a UIButton is pressed
if ([timerCountSeconds isValid]) {
[timerCountSeconds invalidate];
}
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { //Gets called, when you begin touching the screen
//....
if ([decreaseTimer isValid]) {
[decreaseTimer invalidate];
}
timerCountSeconds = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(runTimer) userInfo:nil repeats:YES];
//....
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {//Gets called, when you stop touching the screen(not if you press the UIButton for -(id)initialize)
//...
decreaseTimer = [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(decrease) userInfo:nil repeats:YES];
//...
}
-(void)comept3 { //Gets calles when you rubbed the screen a bit
if ([timerCountSeconds isValid]) {
[timerCountSeconds invalidate];
}
}


What did I do wrong?
Can you please help me?

Answer

You should set an NSTimer object to nil after you invalidate it, since the invalidate method call also does a release (as per the Apple docs). If you don't, calling a method on it like isValid could cause your crash.