Memory leaks

[dev4dev]

Every single usage of something like this

[label whenTapped:^{
    // code here
}];

cause a memory leak like this

• used from cocoapods, SDK 6.1, deploy target 5.0

[dev4dev]

anybody is alive?

[zwaldowski]

This behavior is by design; it isn't an actual leak in BlocksKit. Blocks retain the objects referenced inside the block's scope, so this will cause a retain cycle if the block references something that retains the view. For example, if you add a block to a view from within a view controller's -viewDidLoad, then the block retains the view controller which the retains the view which retains the block, and so on forever and ever. Clang can detect this kind of thing itself if it's a simple case (a block property on the class is capturing self) and warn you about it, even.

To fix this yourself, you'll want to __weak reference the object that causes the retain cycle. Depending on how the block gets called, you also might want to __strong reference the weak reference inside the block. That'd look something like this, using our previous UIViewController example:

- (void)viewDidLoad {
    __weak MyViewController *weakSelf = self;
    [self.tappableView whenTapped:^{
        __strong MyViewController *strongSelf = weakSelf;
        [strongSelf doSomething];
    }];
}

You could also use libextobjc's strongify and weakify macros to do it, same type of thing but prettier.

Alternatively, we could add a method to BlocksKit to remove all view blocks and forcibly break the cycles, but it's better in my humble opinion if you know why it's happening yourself. ;-)

[dev4dev]

Thanks for answer.
I know about retain cycles. And it happens even if code block is empty.
And I was surprised, because using addHandler for UIButton doesn't have the same behavior and everything is clear.
Ok, never mind =)