As I believe you correctly diagnosed, using self will not necessarily cause strong reference cycle in this scenario. But this will retain the view controller while the network operation completes, and in this case (as in most cases), there’s no need to. Thus, it may not be necessary to do use weakSelf, but probably prudent … Read more
Your code will work fine: the weak reference will not cause a retain cycle as you explicitly instruct ARC not to increase the retainCount of your weak object. For best practice, however, you should create a strong reference of your object using the weak one. This won’t create a retain cycle either as the strong … Read more
No, it is not needed in this case. animations and completion are not retained by self so there is no risk of strong retain cycle.
Unless there is some other reference to the parent or child, they both become orphaned. But the retain cycle between the parent and child prevent either from being released and they become wasted memory. A child should never retain a parent. If anything, use a weak reference in the child to maintain a reference to … Read more
The proposed code: __weak id weakSelf = self; timer = [NSTimer scheduledTimerWithTimeInterval:30.0f target:weakSelf selector:@selector(tick) userInfo:nil repeats:YES]; has the effect that (i) a weak reference is made to self; (ii) that weak reference is read in order to provide a pointer to NSTimer. It won’t have the effect of creating an NSTimer with a weak reference. … Read more
Assuming, self is an object pointer to a UIViewController. Things to consider: A UIViewController is a “UIKit” object. UIKit objects shall not be sent methods on non-main threads, that is – those methods must execute on the main thread only! A block that has been enqueued in a queue – whether this was synchronously or … Read more
If self could be nil in the closure use [weak self]. If self will never be nil in the closure use [unowned self]. If it’s crashing when you use [unowned self] I would guess that self is nil at some point in that closure, which is why you had to go with [weak self] instead. … Read more