Question

I have a custom class, and that class has a UIButton instance variable. I have added this code in the class designated initializer:

theFishDeathView = [UIButton buttonWithType:UIButtonTypeCustom];
[theFishDeathView setFrame:CGRectMake(15, 15, 50, 50)];
[theFishDeathView setImage:[UIImage imageNamed:@"Small fish - death.png"] forState:UIControlStateNormal];

So this should properly allocate / initialize the button. And truly enough, the button get’s displayed on the screen when this is called (and of course added as a subview).

Now, I call this method on my object:

[theFishDeathView addTarget:self action:@selector(sellFish) forControlEvents:UIControlEventTouchDown];

And here is the sellFish method:

-(void) sellFish {
    thePlayer.dollars += worthInDollars * 3;
    [theFishDeathView removeFromSuperview];
}

But when I try and press the button, it doesn’t call that method. Am I missing something here?

For the sake of completeness, here is the Fish.h file. It is clear that theFishDeathView is an instance member of the Fish object.

#import <Foundation/Foundation.h>

@interface Fish : NSObject
{
    float cookingTime;
    float weight;
    int worthInDollars;
    NSString *name;
    NSArray *animaionImages;

    int fishMovementSpeed;
}

// Will be used to display
@property (nonatomic, retain) UIImageView *theFishImageView;
@property (nonatomic, retain) UIButton *theFishDeathView;

// Create setter / getter methods
@property (nonatomic, retain) NSString *name;
@property (readonly) int worthInDollars;
@property (readonly) int fishMovementSpeed;

-(id) initWith: (NSString *)theName andWeight: (float)theWeight andCookingTime: (float)theCookingTime andValue: (int)theValue andMovementSpeed: (int)speed;

-(CGRect) newFrameWithWidth:(int)width andHeight:(int)height;

-(void) killFish;

// Cooking methods
-(void) startCooking;
-(void) isDoneCooking;
-(void) isOverCooked;
-(void) sellFish;

@end

Answer 1

I wanted people to know i found the error (with some help from the Apple developers forum) – it was a memory leak. I was trying to send a message to a zombie object (i.e a deallocated object). I thought it was retained by adding it as a subview, but i totally forgot it was the BUTTON i added as a subview, and NOT the class that contained the button. So the class itself got deallocated, and the button was retained, he’s the reason why i could still press it.

For others dealing with similar issues, turn on the Zombie Objects Enabled thing in the plist.info file. That way, you will get an error message like this: “Trying to send action to deallocated object”.

Thanks for trying to help me out 🙂