Passing arguments to selector in Swift

Question

I'm programmatically adding a UITapGestureRecognizer to one of my views:

let gesture = UITapGestureRecognizer(target: self, action: #selector(self.handleTap(modelObj:myModelObj)))  self.imageView.addGestureRecognizer(gesture)  func handleTap(modelObj: Model) {   // Doing stuff with model object here } 

The first problem I encountered was "Argument of '#selector' does not refer to an '@Objc' method, property, or initializer.

Cool, so I added @objc to the handleTap signature:

@objc func handleTap(modelObj: Model) {   // Doing stuff with model object here } 

Now I'm getting the error "Method cannot be marked @objc because the type of the parameter cannot be represented in Objective-C.

It's just an image of the map of a building, with some pin images indicating the location of points of interest. When the user taps one of these pins I'd like to know which point of interest they tapped, and I have a model object which describes these points of interest. I use this model object to give the pin image it's coordinates on the map so I thought it would have been easy for me to just send the object to the gesture handler.

Answer 1

It looks like you're misunderstanding a couple of things.

When using target/action, the function signature has to have a certain form…

func doSomething() 

or

func doSomething(sender: Any) 

or

func doSomething(sender: Any, forEvent event: UIEvent) 

where…

The sender parameter is the control object sending the action message.

In your case, the sender is the UITapGestureRecognizer

Also, #selector() should contain the func signature, and does NOT include passed parameters. So for…

func handleTap(sender: UIGestureRecognizer) {      } 

you should have…

let gesture = UITapGestureRecognizer(target: self, action: #selector(handleTap(sender:))) 

Assuming the func and the gesture are within a view controller, of which modelObj is a property / ivar, there's no need to pass it with the gesture recogniser, you can just refer to it in handleTap

Answer 2

Step 1: create the custom object of the sender.

step 2: add properties you want to change in that a custom object of the sender

step 3: typecast the sender in receiving function to a custom object and access those properties

For eg: on click of the button if you want to send the string or any custom object then

step 1: create

class CustomButton : UIButton {      var name : String = ""     var customObject : Any? = nil     var customObject2 : Any? = nil      convenience init(name: String, object: Any) {         self.init()         self.name = name         self.customObject = object     } } 

step 2-a: set the custom class in the storyboard as well

step 2-b: Create IBOutlet of that button with a custom class as follows

@IBOutlet weak var btnFullRemote: CustomButton! 

step 3: add properties you want to change in that a custom object of the sender

btnFullRemote.name = "Nik" btnFullRemote.customObject = customObject btnFullRemote.customObject2 = customObject2 btnFullRemote.addTarget(self, action: #selector(self.btnFullRemote(_:)), for: .touchUpInside) 

step 4: typecast the sender in receiving function to a custom object and access those properties

@objc public func btnFullRemote(_ sender: Any) {  var name : String = (sender as! CustomButton).name as? String  var customObject : customObject = (sender as! CustomButton).customObject as? customObject  var customObject2 : customObject2 = (sender as! CustomButton).customObject2 as? customObject2  }