Iphone NSTimer Issue - iphone

Question

Hi I am new to objective c. I am trying to make an app for iphone. I have a button on my view, and the click on which the function playSound is called. This is working properly. It does plays the sound that i want it to.
Now the problem is with the timer. I want the timer to start on the click on the same button, and the timer value will be displayed in a label. I am not very clear with the NSTimer itself either yet. I guess i am doing something wrong here. Can anyone help me with this.
-(IBAction)playSound { //:(int)reps
NSString *path = [[NSBundle mainBundle] pathForResource:#"chicken" ofType:#"wav"];
NSURL *fileURL = [[NSURL alloc] initFileURLWithPath: path];
AVAudioPlayer* theAudio = [[AVAudioPlayer alloc] initWithContentsOfURL:fileURL error:nil];
theAudio.delegate = self;
[theAudio play];
[self startTimer];
}
- (void)startTimer {
timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(targetMethod) userInfo:nil repeats:YES];
labelA.text = [NSString stringWithFormat:#"%d", timer];
}
Using the code above, when i click on the button, it plays the sound, and then my app closes.
Thanks
Zeeshan

Answer 1

This line:
labelA.text = [NSString stringWithFormat:#"%d", timer];
makes absolutely no sense. The timer will call the method you specify as the selector in scheduledTimerWithTimeInterval:target:selector:userInfo:repeats: when it fires so you have to implement that method and update your label there. The first line of startTimer is almost correct, but the selector must include a colon (because it denotes a method that takes one parameter):
- (void)startTimer {
timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(timerFired:) userInfo:nil repeats:YES];
}
Note that I named the selector timerFired: so we have to implement that method. If you want the timer to increment a counter, you will have to do that in this method, too:
- (void)timerFired:(NSTimer *)timer {
static int timerCounter = 0;
timerCounter++;
labelA.text = [NSString stringWithFormat:#"%d", timerCounter];
}
Don't forget to invalidate the timer later when you no longer need it.