ios - 添加 uiview 作为背景 View

Question

我有以下模糊 View ，我想将其作为背景 View 。问题是它成为第一个 View ，隐藏在标签/单元格等下面。我认为 self.sendSubview(toBack:blurEffectView) 会这样做 - 你知道为什么吗？ :

更新:还尝试过:self.insertSubview(blurEffectView, BelowSubview: self)

import Foundation
import UIKit

extension UIView
{
    func addBlurEffect()
    {
        if !UIAccessibilityIsReduceTransparencyEnabled() {

            self.backgroundColor = UIColor.clear
            let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.light)
            let blurEffectView = UIVisualEffectView(effect: blurEffect)
            blurEffectView.frame = self.bounds
            blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
            self.addSubview(blurEffectView)
            self.sendSubview(toBack: blurEffectView)
        } else {
            self.backgroundColor = UIColor.white
        }

    }
}

Answer 1

事实证明，只有使用UIViewController或UItableView时才会这样。

import Foundation
import UIKit

extension UIView
{
    func addBlurEffect()
    {
        if !UIAccessibilityIsReduceTransparencyEnabled() {

            self.backgroundColor = UIColor.clear
            let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.light)
            let blurEffectView = UIVisualEffectView(effect: blurEffect)
            blurEffectView.frame = self.bounds
            blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

            if (self is UICollectionView){
                (self as! UICollectionView).backgroundView = blurEffectView
            }else{
                self.addSubview(blurEffectView)
                self.insertSubview(blurEffectView, belowSubview: self)
            }

        } else {
            self.backgroundColor = UIColor.white
        }

    }
}