Notes from Capturing Values In Swift Closures

Within a closure, referring to variables outside of the closure, strong references are created.

class MyClass {
    let a = 1
    let myClosure = {
        print(self.a)
    }
    myClosure() // 1
    a = 2
    myClosure() // 2
}

If we don’t want the strong ref, we can specify weak



class MyClass {
    let a = 1
    let myClosure = { [weak self] in
        guard let strongSelf = self else { return }
        print(strongSelf.a)
    }
    myClosure() // 1
    a = 2
    myClosure() // 1    <-- here's the difference
}