iOS UISwitch "animated: Bool" not working

user_14854771 0
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I'm trying to set the transition animation options for the Switch I created on the screen.

So I used the Instance Method below.

func setOn(_ on: Bool, animated: Bool)

I saw description in the apple dev documentation that the second param decide the difference in animation, but in reality both true/false worked with animation included. https://developer.apple.com/documentation/uikit/uiswitch/1623686-seton

Emulator demonstration gif image

I tested it with a real phone, but it was the same issue. Environment I checked:

  • macOS Catalina 10.15.7
  • Xcode 12.1
  • Simulator: iOS 14.2, iOS 13.7, iOS 13.1
  • iPhone XR (iOS 14.2)

Here is my code : (The only difference is the value of "animated: Bool")

    self.switch1 = UISwitch()
    self.switch1.frame = CGRect(x: 120, y: 150, width: 50, height: 30)
    self.switch1.setOn(true, animated: true)
    self.view.addSubview(switch1)

    self.switch2 = UISwitch()
    self.switch2.frame = CGRect(x: 120, y: 250, width: 50, height: 30)
    self.switch2.setOn(true, animated: false)
    self.view.addSubview(switch2)

What's wrong and how can I turn off the animation options?

swift xcode uikit ios
2 Answers

This animation is default UISwitch feedback on user interaction, you cannot disable that animation from direct interaction, but we can prevent it overriding control and use own interaction (and still keep possibility to animate it if needed programmatically).

Tested with Xcode 12.1 / iOS 14.1

demo

Here is possible approach:

class MySwitch: UISwitch {
    override init(frame: CGRect) {
        super.init(frame: frame)

        let view = UIView()
        view.isUserInteractionEnabled = true

        self.addSubview(view)
        view.translatesAutoresizingMaskIntoConstraints = false
        view.leadingAnchor.constraint(equalTo: self.leadingAnchor).isActive = true
        view.trailingAnchor.constraint(equalTo: self.trailingAnchor).isActive = true
        view.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
        view.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true

        let gr = UITapGestureRecognizer(target: self, action: #selector(toggle(_ :)))
        view.addGestureRecognizer(gr)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    @objc func toggle(_ sender: Any?) {
        self.setOn(!self.isOn, animated: false)
    }
}
user_122990300

You have to force call the 'setOn' callback every time you press the switch. However, in order for the tapGestureRecognizer to respond to your callback, you have to eliminate all other default gestureRecognizers (found on the subviews).

private func initView() {
    uiSwitch = UISwitch(frame: .zero)
    
    // remove all underlaying subviews gesture recognizers
    if let subviews = uiSwitch?.subviews {
        for subview in subviews {
            let gestures = subview.gestureRecognizers
            gestures?.forEach { subview.removeGestureRecognizer($0) }
        }
    }
    
    // add new preferred gesture recognizer
    uiSwitch?.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(switchHasBeenPressed)))
}

@objc
private func switchHasBeenPressed() {
    guard let uiSwitch = uiSwitch else { return }
    uiSwitch.setOn(!uiSwitch.isOn, animated: false)
}
user_74515610
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