未触发touchUpInside事件

Question

I'm new to IOS programming , but strangely same code works in a different class so I don't have any idea why isn't it working It's in Swift 3

class BottomMenu : NSObject{

    //Container view
    var bottomView: UIView!    

    //Button
    var buttonContents : UIButton!


    init(bottomView : UIView) {
        super.init()
        self.bottomView = bottomView        

        buttonContents = UIButton(frame: getFrame(index: 0))    
        buttonContents.backgroundColor = UIColor.blue //To see where to click on the screen
        bottomView.addSubview(buttonContents)

        buttonContents.addTarget(self, action: #selector(onClick), for: .touchUpInside)
    }

    func getFrame(index : CGFloat!) -> CGRect{
        let screenW = UIScreen.main.bounds.width
        return CGRect(x: (screenW/3) * index,
                           y: 0,
                           width: screenW/3,
                           height: self.bottomView.frame.size.height)
    }    
    func onClick(sender: UIButton!){
        NSLog("click")
    }

}

here's the implementation of this class :

let bottomMenu = BottomMenu(bottomView: bottomNavBarContainer)

So, the "click" log never shows

Answer 1

Your code works fine in Playground. The error must be in the usage of the class. Parent view has userInteraction disabled or such.

import UIKit
import Foundation
import PlaygroundSupport

class BottomMenu : NSObject{

//Container view
var bottomView: UIView!

//Button
var buttonContents : UIButton!


init(bottomView : UIView) {
    super.init()
    self.bottomView = bottomView

    buttonContents = UIButton(frame: getFrame(index: 0))
    buttonContents.backgroundColor = UIColor.blue //To see where to click on the screen
    bottomView.addSubview(buttonContents)

    buttonContents.addTarget(self, action: #selector(onClick), for: .touchUpInside)
}

func getFrame(index : CGFloat!) -> CGRect{
    let screenW = UIScreen.main.bounds.width
    return CGRect(x: (screenW/3) * index,
                  y: 0,
                  width: screenW/3,
                  height: self.bottomView.frame.size.height)
}
func onClick(sender: UIButton!){
    NSLog("click")
}

}

var container = UIView(frame: CGRect(x: 0.0, y: 0.0, width: 100.0, height: 100.0))
let view = UIView(frame: CGRect(x: 0.0, y: 0.0, width: 100.0, height: 100.0))
container.addSubview(view)
let buttonContents = BottomMenu(bottomView: view)

PlaygroundPage.current.liveView = container

Answer 2

NSObject is not a UIResponder, so it cannot process UIEvent. A solution could be to make the class descend from UIView instead of NSObject or exposing the button to add the target inside of a ViewController.

Answer 3

The selector #selector(onClick) indicates a function with no parameters. Your onClick function has a single parameter, so the selector should be #selector(onClick(sender:)) . At least I think that's the selector format in Swift 3. I'm Still getting used to Swift selector syntax.

Answer 4

For Swift 3 adaptation, there are two main changes when adding a target.

1. Change your selector to

    buttonContents.addTarget(self, action: #selector(BottomMenu.onClick(_:)), for: .touchUpInside) 

2. Add underscore to the method

    func onClick(_ sender: UIButton!){ 

Just to clarify:

class BottomMenu : NSObject{

    //Container view
    var bottomView: UIView!    

    //Button
    var buttonContents : UIButton!


    init(bottomView : UIView) {
        super.init()
        self.bottomView = bottomView        

        buttonContents = UIButton(frame: getFrame(index: 0))    
        buttonContents.backgroundColor = UIColor.blue //To see where to click on the screen
        bottomView.addSubview(buttonContents)

        buttonContents.addTarget(self, action: #selector(self.onClick(_:)), for: .touchUpInside)
    }

    func getFrame(index : CGFloat!) -> CGRect{
        let screenW = UIScreen.main.bounds.width
        return CGRect(x: (screenW/3) * index,
                           y: 0,
                           width: screenW/3,
                           height: self.bottomView.frame.size.height)
    }    
    func onClick(_ sender: UIButton!){
        NSLog("click")
    }

}