与 Xcode 断开连接时，UIButton 不会动态更新状态（选定/默认）

Question

我创建了一个很好用的 UIButton 集，但仅在连接到 Xcode 时（在运行的模拟器和连接的 iPhone 中）。

如果我正在运行模拟器，则选择的按钮将是唯一选择的按钮

如果我“停止”模拟器，任何被选中的按钮都将保持选中的 UI 状态，即使代码专门将其标记为取消选中。

我不确定是什么导致了这种变化，以及为什么在连接模拟器时它会起作用（我可以看到日志，很不方便）。

这是我用来更新按钮状态的代码（我已使用情节提要中的“按钮背景图像”连接图像

        if format == "A" {
            button1.isSelected = true
            button2.isSelected = false
            button3.isSelected = false
        } else if format == "B" {
            button1.isSelected = false
            button2.isSelected = true
            button3.isSelected = false
        } else {
            button1.isSelected = false
            button2.isSelected = false
            button3.isSelected = true
        }

*我不确定是否也应该提及它，但我在尝试修复它时注意到了一些细微差别：

• 我使用的图片是 PNG，具有透明背景
• 使用这些透明图像，当取消选择 UIButton 时，整个按钮变为白色（同样，仅在与 Xcode 断开连接时...当我连接到 Xcode 时，它​​可以正常工作）
• 如果我更改图像并添加背景，那么当取消选择按钮时，它仍然使用“已选择”图像

这是一个关于正在发生的事情的快速视频：https://www.dropbox.com/s/8pcl8lpkbgcr9l5/Example%20Issue.mov?dl=0（前半部分是模拟器连接到 Xcode，后半部分是在我停止运行 xcode 之后）

Answer 1

我不知道您是如何构建源代码的，但我做了一个类似于您上面提供的视频的简单示例。

import UIKit
class DemoViewController: UIViewController {
    @IBOutlet weak var button1: UIButton!
    @IBOutlet weak var button2: UIButton!
    @IBOutlet weak var button3: UIButton!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        setupButton()
    }
    
    func setupButton() {
        // Setup image for the buttons
        self.button1.setImage(UIImage(named: "book"), for: .normal)
        self.button2.setImage(UIImage(named: "headphone"), for: .normal)
        self.button3.setImage(UIImage(named: "img"), for: .normal)
        
        // setup background image for the buttons in the selected state
        // In normal the buttons do not have a background image
        self.button1.setBackgroundImage(UIImage(named: "bg"), for: .selected)
        self.button2.setBackgroundImage(UIImage(named: "bg"), for: .selected)
        self.button3.setBackgroundImage(UIImage(named: "bg"), for: .selected)
        
        // setup target action for the buttons
        self.button1.addTarget(self, action: #selector(showDetail(_:)), for: .touchUpInside)
        self.button2.addTarget(self, action: #selector(showDetail(_:)), for: .touchUpInside)
        self.button3.addTarget(self, action: #selector(showDetail(_:)), for: .touchUpInside)
        
        self.button1.isSelected = true // set default value for the button
    }
    
    
    @objc func showDetail(_ sender: UIButton) {
        // When user touch on the button then all buttons should be unselected
        // Then the target button should be selected
        button1.isSelected = false
        button2.isSelected = false
        button3.isSelected = false
        sender.isSelected = true
        var format = "";
        switch sender {
        case button1:
            format = "A"
        case button2:
            format = "B"
        default:
            format = "C"
        }
        
        // Show the detail screen
        self.performSegue(withIdentifier: "showDetail", sender: format)
    }
    
    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destination.
        // Pass the selected object to the new view controller.
        if let vc = segue.destination as? DetailViewController {
            vc.format = sender as! String
        }
    }
}