Swift class with uibutton.addTarget to UIView not working

Question

I created a new file with the following class:

import Foundation
import UIKit

var Feld = classFeld()

class classFeld {

     let button = UIButton()

     func createButton() -> UIButton {
         button.frame = CGRect(x: 10, y: 50, width: 200, height: 100)
         button.backgroundColor=UIColor.black
         button.addTarget(self, action: #selector(ButtonPressed(sender:)), for: .touchUpInside)
        return button
    }

    @objc func ButtonPressed(sender: UIButton!) {
        button.backgroundColor=UIColor.red
    }
}

And this is my ViewController:

import UIKit

class ViewController: UIViewController {

   override func viewDidLoad() {
        super.viewDidLoad()
        mainview.addSubview(Feld.createButton())
        self.view.addSubview(mainview)
    }

    var  mainview=UIView()
}

When I start the app a black button is created but when I click on it it doesnt color red. If I add the button instead of

mainview.addSubview(Feld.createButton())

to

self.view.addSubview(Feld.createButton())

it works and the button turns red.

May I anyone explain me why? It should make no difference if I add something to self.view or to a subview which is then added to self.view?

How you are setting frames for mainview ? – Sharad Chauhan Jul 17 '18 at 08:54 — Sharad Chauhan, Jul 17 '18 at 08:54
I didnt set at all. It works with setting it. Thanks – Andy Jul 17 '18 at 09:01 — Andy, Jul 17 '18 at 09:01

Shehata Gamal · Accepted Answer · 2018-07-17T09:12:05.537

2

Because you need to give it a frame and add it to self.view

var mainview = UIView()

edited Jul 17 '18 at 09:12

answered Jul 17 '18 at 08:56

Shehata Gamal

98,760
8
65
87

Adding a frame works! Thanks a lot. I dont understand though why the button is displayed (black) without a frame. And addTarget (turning red) is not displayed without a frame. – Andy Jul 17 '18 at 09:00
This always happens with frames , actually the mainView had a zero default frame , but if you set **mainview.clipsToBounds = true** the button won't show – Shehata Gamal Jul 17 '18 at 09:06

score 1 · Answer 2 · answered Jul 17 '18 at 09:01

This is because you are just initializing a UIView without giving it any frame and adding it to the main view.

You need to give frame to your mainview also. For example :

class ViewController: UIViewController {
   var mainview = UIView()
   override func viewDidLoad() {
        super.viewDidLoad()
        mainview.frame = CGRect(x: 10, y: 50, width: 300, height: 300)
        self.view.addSubview(mainview)
        mainview.addSubview(Feld.createButton())
    }        
}

score 1 · Answer 3 · answered Jul 17 '18 at 09:01

1

Here is changes on ViewController class and working fine:

class ViewController: UIViewController {
    var  mainview: UIView!
    override func viewDidLoad() {
        super.viewDidLoad()
        mainview = UIView(frame: self.view.bounds)
        mainview.addSubview(Feld.createButton())
        self.view.addSubview(mainview)

    }
}

answered Jul 17 '18 at 09:01

Moayad Al kouz

1,342
1
9
19

The issue is at mainView frame – Moayad Al kouz Jul 17 '18 at 09:01

Swift class with uibutton.addTarget to UIView not working

3 Answers3