Strange state change(UIControlState) of UIButton

Question

I got a strange UIButton result while understanding concept of UIControlState. Here is my simple code related to UIButton.

import UIKit

class ViewController: UIViewController {

    let normalBtn: UIButton = {
        let button = UIButton()

        button.frame = CGRect(x: 80, y: 200, width: 200, height: 100)

        button.setTitle("", for: .normal)
        button.setTitle("", for: .highlighted)
        button.setTitle("", for: .selected)
        button.setTitle("", for: .focused)

        button.titleLabel?.font = UIFont.systemFont(ofSize: 50)

        return button
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        view.addSubview(normalBtn)

        normalBtn.addTarget(self, action: #selector(btnSelected), for: .touchUpInside)

    }

    @objc func btnSelected() {
        print("highlight", normalBtn.isHighlighted)

        normalBtn.isSelected = !normalBtn.isSelected
    }

}

Here is my scenario about this code.

When I touch normalBtn, state of this button changes normal to selected.
When I touch normalBtn again, its state changes from selected to normal.
While these transitions, highlighted property also should be changed, when I touch normalBtn.

So my expectation of changing title is

-> while touching -> (normal to selected)
-> while touching -> (selected to normal)

But the result is,

-> while touching -> (normal to selected)
-> (selected to normal)

I really don't know why. Any ideas about this question? Thanks.

From my knowledge, the highlighted state won't come from Selected to normal transition. Vice-versa works. Probably it's de-highlighting — Sivajee Battina, Nov 20 '17 at 04:40
@SivajeeBattina Then, is there a way to catch a point of de-highlighting like `normalBtn.isDeHighlighted`? — Changnam Hong, Nov 20 '17 at 04:48
I expected this question. But there is no catching of de-highlighting. — Sivajee Battina, Nov 20 '17 at 04:51
@SivajeeBattina Inside of `btnSelected()`, `print("highlight", normalBtn.isHighlighted)` statement always prints `true`. Is this phenomenon is related to de-highlighting? — Changnam Hong, Nov 20 '17 at 04:56

score 3 · Accepted Answer · edited May 21 '21 at 12:00

3

Try adding selected state combining with highlighted state.

Example:

button.setTitle("", for: UIControlState.selected.union(.highlighted))

edited May 21 '21 at 12:00

Zoe

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answered Nov 20 '17 at 05:44

Van

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1

as @sivajee said:" the highlighted state won't come from Selected to normal transition", so apple provides way to combine states together, just like in your case. and since highlight state comes before the selected/normal state, your case is satisfying. :) – Van Nov 20 '17 at 07:35
Thank you for your explanation! Now I understand how to use it. – Changnam Hong Nov 20 '17 at 07:54
my pleasure . :) – Van Nov 20 '17 at 12:16

score 0 · Answer 2 · edited May 21 '21 at 12:00

0

Alternative syntax to the accepted answer:

button.setTitle("", for: [.selected, .highlighted])

edited May 21 '21 at 12:00

Zoe

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21
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answered May 21 '21 at 09:01

Stanislav M.

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Strange state change(UIControlState) of UIButton

2 Answers2