UIButton with multiple target actions for same event

问题

Can I add multiple target actions on a UIButton for the same event like below?

[button addTarget:self action:@selector(xxx) forControlEvents:UIControlEventTouchUpInside];
[button addTarget:object action:@selector(yyy) forControlEvents:UIControlEventTouchUpInside];

I made a quick app to test it out and it carries out both the actions on button press.

I want to know if it's good practice to do so, and also will the order of execution always remain the same?

Thanks in advance.

Edit: I did find this post which states it's called in reverse order of addition, i.e., the most recently added target is called first. But it's not confirmed

回答1:

Yes it is possible to add multiple actions to a button.

personally i would prefer a Delegate to subscribe to the button. Let the object you want to add as target subscribe on the delegate's method so it can receive events when you press the button.

A single action that forwards the event to other methods to be fully in control

A simple test in swift

import UIKit

class ViewController: UIViewController {

  override func viewDidLoad() {
      super.viewDidLoad()
      // Do any additional setup after loading the view.

      let button = UIButton(frame: CGRect(x: 50, y: 50, width: 300, height: 30))
      button.backgroundColor = .orange
      button.addTarget(self, action: #selector(action1), for: .touchUpInside)
      button.addTarget(self, action: #selector(action2), for: .touchUpInside)
      button.addTarget(self, action: #selector(actionHandler), for: .touchUpInside)
      self.view.addSubview(button)
  }

  @objc func actionHandler(_ sender: UIButton){
      print("actionHandler")
      action1(sender)
      action2(sender)
  }

  @objc func action1(_ sender: UIButton) {
      print("action1")
  }

  @objc func action2(_ sender: UIButton) {
      print("action2 \n")
  }
}

Output after one click:

action1
action2 

actionHandler
action1
action2

Can you confirm on the order of execution when normally adding the actions

Yes it is executed in the order you set the targets.

来源：https://stackoverflow.com/questions/56244140/uibutton-with-multiple-target-actions-for-same-event

标签

ios

objective-c

uibutton