Help stopping audio using AVAudioPlayer - iphone

Question

Alright I have two problems. I'm using AVAudioPlayer to play a simple audio file in .caf format. What I'm trying to do is have a play and pause button. Here is a sample of a simple IBAction to play the audio from a button.
- (IBAction) clear {
NSString *path = [[NSBundle mainBundle] pathForResource:#"clear" ofType:#"caf"];
AVAudioPlayer* myAudio=[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL];
myAudio.delegate = self;
myAudio.volume = 1.0;
myAudio.numberOfLoops = 0;
[myAudio play];
}
So when I go ahead and create another IBAction with the method...
- (IBAction) stopaudio {
[myAudio stop];
audioPlayer.currentTime = 0;
}
I compile and xcode tells me that myAudio in the stopaudio IBAction is not defined. How do I fix it so I'm able to access myAudio in another IBAction?
My Second question is that I'm using NavigationController to setup a TableView, when I make a selection it takes me to a UIView with a back button to go back to the TableView. What I'm trying to do is to kill any audio that I have playing in the UIView when I go back to the TableView. The code above is part of the code that I'm going to have in the UIView.
Also one quick question. Lets say I have an audio file that is 1 minute long. Clicking play again will overlap a new instance of that audio before the old instance is done playing. How can I check to see if myAudio is playing and not allow it to be played again until myAudio is finished playing?
Thank You!

Answer 1

First of all, you should read the documentation. It will remove almost all of your questions. Nevertheless, to have access to your instance of AVAudioPlayer from all methods of your class, you should define it in your .h file. To stop your player on returning to the previous screen, call [myAudio stop] in your viewWillDisappear:(BOOL)animated method. About your last question. If you define myAudio in your .h file, you will be able to check if it is playing now. smth like
- (IBAction) clear {
if(![myAudio isPlaying]){
[myAudio play];
}
}