Question

Alright, so I’m running into an issue with my code. What I have done is subclassed UIButton so I can give it some more infomormation that pertain to my code. I have been able to create the buttons and they work great. Capiche.

However, one of the things I want my subclass to hold is a reference to a NSMangedObject. I have this code in my header file:

@interface ButtonSubclass : UIButton {
    NSManagedObjectContext *context;
    NSManagedObject *player;
}

@property (nonatomic, retain) NSManagedObject *player;
@property (nonatomic, retain) NSManagedObjectContext *context;

- (id)initWithFrame:(CGRect)frame andTitle:(NSString*)title;
//- (void)setPlayer:(NSManagedObject *)aPlayer;

@end

As you can see, it has a instance variable to the NSMangedobject I want it to hold (as well as the Context). But for the life of me, I can’t get it to hold that NSManagedObject. I run both the @synthesize methods in the Implementation file.

@synthesize context;
@synthesize player;

So I’m not sure what I’m doing wrong. This is how I create my button:

ButtonSubclass *playerButton = [[ButtonSubclass alloc] initWithFrame:frame andTitle:@"20"]; //works

        playerButton.context = self.context; //works
        playerButton.player = [players objectAtIndex:i]; //FAILS

And I have initilaized the players array earlier, where I get the objects. Another weird thing is that when it gets to this spot in the code, the app crashes (woot) and the the console output stops. It doesn’t give me any error, and notification at all that the app has crashed. It just… stops. So I don’t even know what the error is that is crashing the code, besides it has to do with that line up there setting the “player” variable. Thoughts and ideas? I’d love your wisdom!

Answer 1

There is no particular reason why the code you have shouldn’t work. You can assign a NSManageObject instance as an attribute. The simplest explanation for the crash is an out of bounds error for the array. When you don’t get an error from the consoles its usually because the debugger has crashed. That is usually caused by having some kind of recursion that causes the debugger stack to overflow.

However, putting data logic in a view element like a button is very, very poor practice. This completely breaks the MVC design pattern and will make your code fragile and hard to maintain. UI elements should be “dumb” and only understand how to display any data handed to them, they shouldn’t be involved in actually tracking the data itself. That is the function of the controller and the data model respectively.

Ideally, the “player” object should be tracked by the data model which the controller then links to the appropriate UI button or other UI element. Putting the tracking of the player in the data model makes the design flexible which makes it easy to expand, reuse and maintain.