Question

I have a class like this:

@interface MyCollection : NSObject {
    NSMutableDictionary *data;
}

and in the implementation of it, I have a method to init it like this:

- (id) init {
    if(self = [super init])
    {
        self.data = [[NSMutableDictionary alloc] init];
    }
    return self;
}

Now when I create a object of this class in my code like this:

MyCollection *c = [[MyCollection alloc] init];

… at which point the Leaks utility shows that I have a memory leak in the init function on the very line where I try to set up the instance variable. I am totally new to Objective C & Iphone and I can’t just get what is going wrong here. I have read through the Memory Management Guide and all, but I think I’m missing something pretty serious here.

Any help would be greatly appreciated. Thanks for your time already.

Answer 1

you are using self.data =. So there is most likely a property. And it most likely is a property which either copies or retains your object if you use it.
By calling

 self.data = [[NSMutableDictionary alloc] init];

The retain count of the NSMutableDictionary increases because of the alloc, and if the property of data has a retain or copy statement you get another increase in retain count.

you could write data = [[NSMutableDictionary alloc] init]; or self.data = [NSMutableDictionary dictionary]. This would increase the retain count only one time.

And don’t forget to release the object in dealloc.