Question

In playpauseAction Method execution it will play audio file as well as load multiple viewcontrollers

-(void)playpauseAction:(id)sender 
{

 if  

  ([audioPlayer isPlaying]){

 [sender setImage:[UIImage imageNamed:@"play.png"] forState:UIControlStateSelected];

      [audioPlayer pause];

  } else {

 [sender setImage:[UIImage imageNamed:@"pause.png"] forState:UIControlStateNormal];

      [audioPlayer play];

      self.timer = [NSTimer scheduledTimerWithTimeInterval:11 target:self selector:@selector(displayviewsAction:) userInfo:nil repeats:NO];
  }  

}

While loading these view controllers just want to check in every viewcontroller that if audioplayer is paused then invalidate timer if not then continue loading of viewcontroller with NSTimer

- (void)displayviewsAction:(id)sender
{

FirstViewController *viewController = [[FirstViewController alloc] init];

viewController.view.frame = CGRectMake(0, 0, 320, 480);

[self.view addSubview:viewController.view];

[self.view addSubview:toolbar];

if  

    ([audioPlayer pause]){

    [timer invalidate];

    } else {

   self.timer = [NSTimer scheduledTimerWithTimeInterval:23 target:self selector:@selector(secondViewController) userInfo:nil repeats:NO];  

}  
[viewController release];
}

My problem is when i add if statement in displayviewAction method it gives me red warning message that statement requires expression of scalar type (void invalid).

But if statement in the playpauseAction works fine.

Why the if statement of displayviewAction is giving red warning message.

Answer 1

AVAudioPlayer’s pause is defined as:

-(void)pause

so writing:

if([audioPlayer pause]) {...}

corresponds to write:

if(void) {...}

and void is not a scalar type, exactly what the error message tells you.

Probably your intention was to check if the audio player was paused, that is it is not playing :

if([audioPlayer isPlaying]==NO) {...}