Adding a closure as target to a UIButton

Question

I have a generic control class which needs to set the completion of the button depending on the view controller.Due to that setLeftButtonActionWithClosure function needs to take as parameter a closure which should be set as action to an unbutton.How would it be possible in Swift since we need to pass the function name as String to action: parameter.

func setLeftButtonActionWithClosure(completion: () -> Void) {     self.leftButton.addTarget(<#target: AnyObject?#>, action: <#Selector#>, forControlEvents: <#UIControlEvents#>) } 

Answer 1

With iOS 14 Apple has finally added this feature to UIKit. However, someone might still want to use this extension because Apple's method signature is suboptimal.

iOS 14:

extension UIControl {     func addAction(for controlEvents: UIControl.Event = .touchUpInside, _ closure: @escaping()->()) {         addAction(UIAction { (action: UIAction) in closure() }, for: controlEvents)     } } 

pre-iOS 14:

extension UIControl {     func addAction(for controlEvents: UIControl.Event = .touchUpInside, _ closure: @escaping()->()) {         @objc class ClosureSleeve: NSObject {             let closure:()->()             init(_ closure: @escaping()->()) { self.closure = closure }             @objc func invoke() { closure() }         }         let sleeve = ClosureSleeve(closure)         addTarget(sleeve, action: #selector(ClosureSleeve.invoke), for: controlEvents)         objc_setAssociatedObject(self, "\(UUID())", sleeve, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN)     } } 

Usage:

button.addAction {     print("Hello, Closure!") } 

or:

button.addAction(for: .touchUpInside) {     print("Hello, Closure!") } 

or if avoiding retain loops:

self.button.addAction(for: .touchUpInside) { [unowned self] in     self.doStuff() } 

(Extension is included here: https://github.com/aepryus/Acheron)

Also note, in theory .primaryActionTriggered could replace .touchUpInside, but it seems to be currently bugged in catalyst, so I'll leave it as is for now.