Question

I was doing a debug on an application I’m creating, but running instruments I found a memory leak that I can’t be able to understand.

If I try to modify the code following Instruments suggestion, my application crashes because of

message sent to deallocated instance

Can someone help me?

- (void) objectAtIndex:(int)index {
    SpecialObject *specialObj = [SpecialObject sharedInstance];

    id model = [self.datasource objectAtIndex:index];

    if ([model isKindOfClass:[ClassA class]]) {
        ClassA *objA = (ClassA *)model;
        specialObj.title = objA.title;

    } else if ([model isKindOfClass:[ClassB class]]) {
        ClassB *objB = (ClassB *)model;
        specialObj.title = objB.title;
    }
}

self.datasource is a NSMutableArray while specialObj.title is a NSString

They are defined as @property(nonatomic, retain).

My problem is that Instruments tells me that these 2

ClassA *objA = (ClassA *)model;
ClassB *objB = (ClassB *)model;

are leaks, but if I release objA and objB my application crash.

Thanks for any help!

Answer 1

After some search I’ve found the problem: XCode usually tells where the leaks are, but some times it give you a probable position for it.

This means that the memory leak is somewhere in the program flow the goes to the point XCode indicates, not necessarily exactly where it says.

Hope this can help someone else in the future!