Swift Closures - Capturing self as weak

Question

I am trying to resolve a closure based strong reference cycle in Swift.
In the code below, object is retained by the owning view controller. ProgressHUD is

Answer 1

Try the following:

object.setCompletionHandler { [unowned self] (error) -> () in
    if(!error){
        weakSelf?.tableView.reloadData()
    }
    weakSelf?.progressHUD?.hide(false)
}

Answer 2

If you assign a closure to a property of a class instance, and the closure captures that instance by referring to the instance or its members, you will create a strong reference cycle between the closure and the instance. Swift uses capture lists to break these strong reference cycles. source Apple

source sketchyTech First, it is important to make clear that this whole issue only concerns closures where we are assigning "a closure to a property of a class instance". Keep this in mind with each rule. The rules:

1. use weak capture if the class instance or property is an optional
2. use unowned if the class instance or property is non-optional and can never be set to nil
3. "you must ... use the in keyword, even if you omit the parameter names, parameter types, and return type"

In answear to your question there should be no retain cycle.

Answer 3

You stated that progressHUD is retained by the owning view controller (self) and you reference it in your closure...so add it to the capture list and then use the captured variable in the closure as follows:

object.setCompletionHandler { [weak self] (error) -> Void in
    if(!error){
        self?.tableView.reloadData()
    }
    self?.progressHUD.hide(false)
}