ios : Mute Button doesn't work after application enters foreground - ios

Question

I've created a button that stops and plays background music when clicked. It works great, but when I click on the home button, and relaunch the application (background - foreground) the button doesn't work. I click on it and it does nothing. Help please!! Thanks
This is the code:
- (IBAction)muteButtonPressed:(id)sender {
UIImage *currentImage = [self.muteButton currentImage];
UIImage *vol1 = [UIImage imageNamed:#"Volume 1"];
UIImage *vol2 = [UIImage imageNamed:#"Volume 2"];
if ([currentImage isEqual:vol1]) {
[self.muteButton setImage:vol2 forState:UIControlStateNormal];
[self.backgroundMusic stop];
self.scene.playSounds = NO;
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setInteger:0 forKey:#"playSounds"];
[defaults synchronize];
}
if ([currentImage isEqual:vol2]) {
[self.muteButton setImage:vol1 forState:UIControlStateNormal];
[self playBackground];
self.scene.playSounds = YES;
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setInteger:1 forKey:#"playSounds"];
[defaults synchronize];
}
}
and this is the code in the viewcontroller :
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *playSoundsString = [defaults objectForKey:#"playSounds"];
NSInteger playSoundsInt = [playSoundsString intValue];
NSNumber *playSoundsNumber = [NSNumber numberWithInteger:playSoundsInt];
self.scene.playSounds = [playSoundsNumber boolValue];
if (self.scene.playSounds == YES) {
UIImage *vol1 = [UIImage imageNamed:#"Volume 1"];
self.scene.playSounds = YES;
[self playBackground];
[self.muteButton setImage:vol1 forState:UIControlStateNormal];
}
else if (self.scene.playSounds == NO) {
UIImage *vol2 = [UIImage imageNamed:#"Volume 2"];
self.scene.playSounds = NO;
[self.muteButton setImage:vol2 forState:UIControlStateNormal];
}
finally this is when my app enters background (in viewcontroller) :
if (self.scene.playSounds == YES) {
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(stopMusic:) name:#"SOUND_OFF" object:nil];
}