模糊效果沒有出現在UITableViewCell中

Question

我正在嘗試為視圖添加模糊效果。 我像這樣創建了模糊效果

let blurLabel: UIVisualEffectView = {
    let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.dark)
    let blurEffectView = UIVisualEffectView(effect: blurEffect)


    return blurEffectView
    }()

然后像這樣將其添加到子視圖中，並設置約束

 override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: .subtitle, reuseIdentifier: reuseIdentifier)
        let view = tableViewCell

        addSubview(view)
        view.addSubview(blurLabel)

 blurLabel.leftAnchor.constraint(equalTo: self.leftAnchor,constant:0).isActive = true
        //blurLabel.topAnchor.constraint(equalTo: self.topAnchor, constant: 178).isActive = true
        blurLabel.widthAnchor.constraint(equalToConstant: 375).isActive = true
        blurLabel.heightAnchor.constraint(equalToConstant: 180).isActive = true

但是當我運行該應用程序時，它根本沒有出現

Answer 1

編輯：根據@HAS和@Fogmeister的建議，您也可以使用translatesAutoResizingMaskIntoConstraints = false因為這是使用自動布局而不指定顯式框架的更好解決方案。

您必須像這樣將框架分配給UIVisualEffectView ：

 let blurLabel: UIVisualEffectView = {
    let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.dark)
    let blurEffectView = UIVisualEffectView(effect: blurEffect)
    blurEffectView.frame = CGRect(x: 0, y: 0, width: 60, height: 40) //give desirable frame
    return blurEffectView
 }()

Answer 2

如果願意，除了提供明確的框架外，還可以為任何視圖或子視圖提供blurView。

let blurLabel: UIVisualEffectView = {
    let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.dark)
    let blurEffectView = UIVisualEffectView(effect: blurEffect)    
    blurEffectView.frame = myMainview.bounds //Blur effect's frame
    return blurEffectView
}()

override func viewDidLoad() {
    super.viewDidLoad()
    // Use it somewhere using
    self.view.insertSubview(blurEffectView, belowSubview: myAnotherView)
    // You may also use any of the subviews too, instead of the self.view
    /// self.myView.insertSubview(blurEffectView, belowSubview: myAnotherView)
}

Answer 3

要解決此問題，只需停止自動創建約束即可。 像這樣...

let blurLabel: UIVisualEffectView = {
    let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.dark)
    let blurEffectView = UIVisualEffectView(effect: blurEffect)
    // this line will stop constraints being added for a zero frame
    blurEffectView.translatesAutoResizingMaskIntoConstraints = false
    return blurEffectView
}()