retain-cycle

Update: I tried writing it without making it weak, and there doesn't seem to be a leak. So maybe the question is no longer necessary. In Objective-C ARC, when you want to have a closure be able to use itself inside of the closure, the block cannot capture a strong reference to itself, or it will be a retain cycle, so instead you can make the closure capture a weak reference to itself, like so: // This is a simplified example, but there are real uses of recursive closures int (^fib)(int); __block __weak int (^weak_fib)(int); weak_fib = fib = ^(int n) { if (n < 2) return n; else return weak_fib

I thought I understood the usage of self in a block that is copied is a no no . But in an attempt to clean my code i enabled a bunch of warnings in Xcode, one called "Sending messages to weak pointers" so now in all my blocks, every time I use my created weakself reference __weak typeof(self) weakself = self; I get this warning: Weak receiver may be unpredictably set to nil a trivial example: __weak typeof(self) weakself = self; [aClass doSomethingInABlock:^{ [weakself doSomething]; //warning. }]; I have seen answers which define a version of self within the block like so: __weak typeof(self)

I am reading Apple's Swift Programming Language Guide. In the part about Strong Reference Cycle for closures, I tried a different type of closure but it did not give the expected output. class HTMLElement { let name: String let text: String? lazy var asHTML : String = { //[unowned self] in if let text = self.text { return "<\(self.name)>\(text)</\(self.name)>" } else { return "<\(self.name) />" } }() init(name: String, text: String? = nil) { self.name = name self.text = text } deinit { println("\(name) is being deinitialized") } } var paragraph: HTMLElement? = HTMLElement(name: "p", text:

I want self to be non-nil and I'm sure it will be, during the blocks execution. So why explicitly specify [unowned self] ? object.executeBlock { date = self.lastModified } vs object.executeBlock { [unowned self] in date = self.lastModified } Edit: Well i'm getting down votes so let's try again. Q: Let’s say I have a problem. That problem is that I would like to prevent a reference cycle. I have two options. I could use [unowned self] or I could use [weak self]. My question therefore, is this: from these two options, why would I choose [unowned self] ? Why not choose [weak self] everytime ?

Using self. in blocks causes retain cycles, so I need to create a reference to weakSelf . I understand this BUT! If from my block I call a method which uses self ", does this too cause a retain cycle? For instance, if I reload a UITableView from a block and in some of my UITableView delegate methods I call self. , am I causing a retain cycle? Does that mean I have to pass around this weak reference everywhere? Seems hokey. I might be misreading your question, but your wording: If from my block I call a method which uses "self.", does this too cause a retain cycle? For instance if I reload a