Passing functions as parameters in Swift

Oneword answer for your question is Closures

The Default Syntax for closures is () -> ()

Instead of Selector you could directly mention the method definition

func showConfirmBox(msg:String, title:String,    firstBtnStr:String, firstSelector:(sampleParameter: String) -> returntype,    secondBtnStr:String, secondSelector:() -> returntype,    caller:UIViewController) {    //Your Code}

But using this will create readability problems so i suggest you to use typeAlias

typealias MethodHandler1 = (sampleParameter : String)  -> Voidtypealias MethodHandler2 = ()  -> Voidfunc showConfirmBox(msg:String, title:String,                    firstBtnStr:String, firstSelector:MethodHandler1,                    secondBtnStr:String, secondSelector:MethodHandler2) {    // After any asynchronous call    // Call any of your closures based on your logic like this    firstSelector("FirstButtonString")    secondSelector()}

You can call your method like this

func anyMethod() {   //Some other logic    showConfirmBox(msg: "msg", title: "title", firstBtnStr: "btnString",          firstSelector: { (firstSelectorString) in              print(firstSelectorString) //this prints FirstButtonString         },          secondBtnStr: "btnstring") {            //Invocation comes here after secondSelector is called         }}

Just in case anyone else stumbles upon this. I worked out an updated simple solution for Swift 5.1 while I was working through this for while building a global alert utility for a project.

Swift 5.1

Function with Closure:

func showSheetAlertWithOneAction(messageText: String, dismissButtonText: String, actionButtonText : String, presentingView : NSWindow, actionButtonClosure: @escaping () -> Void) {        let alert = NSAlert()        alert.messageText = messageText        alert.addButton(withTitle: actionButtonText)        alert.addButton(withTitle: dismissButtonText)        alert.beginSheetModal(for: presentingView) { (response) in            if response == .alertFirstButtonReturn {                actionButtonClosure()            }        }    }

Function Called:

showSheetAlertWithOneAction(messageText: "Here's a message", dismissButtonText: "Nope", actionButtonText: "Okay", presentingView: self.view.window!) {                                            someFunction()                                }

Adding to got2jam's answer...If you're working with UIAlertController

The generic function to show an alert with closure:

func showAlertAction(title: String, message: String, actionClosure: @escaping () -> Void){  let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)  alertController.addAction(UIAlertAction(title: "Ok", style: UIAlertAction.Style.default, handler: {(action: UIAlertAction!) in actionClosure()}))  self.present(alertController, animated: true, completion: nil)}

Now you can call it like that:

showAlertAction(title: "This is the title", message: "This is the message") {   self.close()}

in this case, close is the particular UIAlertAction to execute

func close(){  dismiss(animated: true, completion: nil)}