Saving the value of UISlider

I've managed to implement a UISlider in Cocos2D which actually works to my surprise.

I've been looking through all the NSUserDefaults samples but I can't get anything to work correctly. Just wondered if anyone could help. I think I have the saving of the value correct.

- (void) valueChanged:(float) value tag:(int) tag{
    if (tag == 1) // music volume
        [self updateLabel:value];
    [CDAudioManager sharedManager].backgroundMusic.volume = value;

    CCLOG (@"Unknown slider");

    NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
    [prefs setFloat:value forKey:@"floatKey"];
    [prefs synchronize];
}

It's just reloading the defaults where I'm kind of stuck, I've put this in the initialization of my class. I'm not even sure if it should go there...

NSUserDefaults *userDefaults = [NSU开发者_如何学运维serDefaults standardUserDefaults];
if ([userDefaults floatForKey:@"floatKey"]) {
    [userDefaults setFloat:value forKey:@"floatKey"];
}

In your initialization, you are setting the value for floatKey in the prefs instead of getting it. You probably want something like this:

NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
float value = [userDefaults floatForKey:@"floatKey"]; //read the value from the defaults
[CDAudioManager sharedManager].backgroundMusic.volume = value; //use the value