Swift UIControlState.Selected 保持选中状态？

Question

我有 3 个按钮供用户选择他们希望查看的类别。

它们的定义如下：

 //outlets
@IBOutlet weak var ChineseButton: UIButton!
@IBOutlet weak var IndianButton: UIButton!
@IBOutlet weak var MexicanButton: UIButton!

我对这些按钮进行了以下操作（将原始图像按钮更改为灰色版本）：

//动作

@IBAction func ChineseButtonPressed(sender: UIButton)
{

    ChineseButton.setImage(UIImage(named: "chinese.png"), forState: UIControlState.Normal)
    ChineseButton.setImage(UIImage(named: "chinese.png"), forState: UIControlState.Selected)
    IndianButton.setImage(UIImage(named: "grey-indian.png"), forState: UIControlState.Normal)
    MexicanButton.setImage(UIImage(named: "grey-mexican.png"), forState: UIControlState.Normal)

}
@IBAction func EightFacedButtonPressed(sender: UIButton) {
         IndianButton.setImage(UIImage(named: "indian.png"), forState: UIControlState.Normal)
IndianButton.setImage(UIImage(named: "indian.png"), forState: UIControlState.Selected)
    ChineseButton.setImage(UIImage(named: "grey-chinese.png"), forState: UIControlState.Normal)

    MexicanButton.setImage(UIImage(named: "grey-mexican.png"), forState: UIControlState.Normal)
}

@IBAction func TweleveFacedButtonPressed(sender: UIButton) {
    MexicanButton.setImage(UIImage(named: "mexican.png"), forState: UIControlState.Normal)
MexicanButton.setImage(UIImage(named: "mexican.png"), forState: UIControlState.Selected)
    ChineseButton.setImage(UIImage(named: "grey-chinese.png"), forState: UIControlState.Normal)
    IndianButton.setImage(UIImage(named: "grey-indian.png"), forState: UIControlState.Normal)   
}

这个动作函数也决定了 UIControlState，我有另一个按钮，一旦点击它会带你到另一个页面，但需要了解哪个按钮被选中。

我尝试了以下，但它似乎无法识别选择了哪个按钮？

 @IBAction func GenerateButton(sender: UIButton) {
        if ChineseButton.selected == true{
            println("Chinese button was selected")
        }

我是 swift 新手，因此我们将不胜感激！

谢谢:)

Answer 1

您没有选择按钮，您只是在更改图像。

首先，您可以简化所有代码并将图像设置一次，正常显示为灰色，选中状态为彩色：

override func viewDidLoad() {
    super.viewDidLoad()

    MexicanButton.setImage(UIImage(named: "mexican.png"), forState: UIControlState.Normal)
    MexicanButton.setImage(UIImage(named: "grey-mexican.png"), forState: UIControlState.Selected)
    ChineseButton.setImage(UIImage(named: "grey-chinese.png"), forState: UIControlState.Normal)
    ChineseButton.setImage(UIImage(named: "chinese.png"), forState: UIControlState.Selected)
    IndianButton.setImage(UIImage(named: "grey-indian.png"), forState: UIControlState.Normal)
    IndianButton.setImage(UIImage(named: "indian.png"), forState: UIControlState.Selected) 
}

您也可以在 Storyboard 上配置此功能，也可以在图标的不同 State Configs 处更改 Image：

然后，在每个操作上，您只需选择按钮，就会显示正确的图像（您可以对所有按钮使用相同的操作）：

@IBAction func AnyButtonPressed(sender: UIButton) {
    // Deselect all buttons but the pressed one
    for button in [ChineseButton, IndianButton, MexicanButton] {
        button.selected = sender === button
    }
}