下面是一个简单的方法来添加自定义模糊，而不用与私有api讨价还价使用UIViewPropertyAnimator:

首先，声明class属性:

var blurAnimator: UIViewPropertyAnimator!

然后在viewDidLoad()中设置你的模糊视图:

let blurEffectView = UIVisualEffectView()
blurEffectView.backgroundColor = .clear
blurEffectView.frame = view.bounds
blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
view.addSubview(blurEffectView)

blurAnimator = UIViewPropertyAnimator(duration: 1, curve: .linear) { [blurEffectView] in
    blurEffectView.effect = UIBlurEffect(style: .light)
}

blurAnimator.fractionComplete = 0.15 // set the blur intensity.    

注意:此解决方案不适用于UICollectionView/UITableView单元格

func blurBackgroundUsingImage(image: UIImage)
{
    var frame                   = CGRectMake(0, 0, self.view.frame.width, self.view.frame.height)
    var imageView               = UIImageView(frame: frame)
    imageView.image             = image
    imageView.contentMode       = .ScaleAspectFill
    var blurEffect              = UIBlurEffect(style: .Light)
    var blurEffectView          = UIVisualEffectView(effect: blurEffect)
    blurEffectView.frame        = frame
    var transparentWhiteView    = UIView(frame: frame)
    transparentWhiteView.backgroundColor = UIColor(white: 1.0, alpha: 0.30)
    var viewsArray              = [imageView, blurEffectView, transparentWhiteView]

    for index in 0..<viewsArray.count {
        if let oldView = self.view.viewWithTag(index + 1) {
            var oldView         = self.view.viewWithTag(index + 1)
            // Must explicitly unwrap oldView to access its removeFromSuperview() method as of Xcode 6 Beta 5
            oldView!.removeFromSuperview()
        }
        var viewToInsert        = viewsArray[index]
        self.view.insertSubview(viewToInsert, atIndex: index + 1)
        viewToInsert.tag        = index + 1
    }
}

自定义模糊比例

你可以尝试UIVisualEffectView自定义设置为-

class BlurViewController: UIViewController {
    private let blurEffect = (NSClassFromString("_UICustomBlurEffect") as! UIBlurEffect.Type).init()

    override func viewDidLoad() {
        super.viewDidLoad()
        let blurView = UIVisualEffectView(frame: UIScreen.main.bounds)
        blurEffect.setValue(1, forKeyPath: "blurRadius")
        blurView.effect = blurEffect
        view.addSubview(blurView)
    }   
}

输出:- for blureeffect . setvalue(1…& blurEffect.setValue (2 . .

你可以使用UIVisualEffectView来实现这个效果。这是一个本地API，经过了性能和电池寿命的微调，而且很容易实现。

迅速:

//only apply the blur if the user hasn't disabled transparency effects
if !UIAccessibility.isReduceTransparencyEnabled {
    view.backgroundColor = .clear

    let blurEffect = UIBlurEffect(style: .dark)
    let blurEffectView = UIVisualEffectView(effect: blurEffect)
    //always fill the view
    blurEffectView.frame = self.view.bounds
    blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

    view.addSubview(blurEffectView) //if you have more UIViews, use an insertSubview API to place it where needed
} else {
    view.backgroundColor = .black
}

objective - c:

//only apply the blur if the user hasn't disabled transparency effects
if (!UIAccessibilityIsReduceTransparencyEnabled()) {
    self.view.backgroundColor = [UIColor clearColor];

    UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];
    UIVisualEffectView *blurEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
    //always fill the view
    blurEffectView.frame = self.view.bounds;
    blurEffectView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

    [self.view addSubview:blurEffectView]; //if you have more UIViews, use an insertSubview API to place it where needed
} else {
    self.view.backgroundColor = [UIColor blackColor];
}

如果你以模态方式呈现这个视图控制器来模糊底层内容，你需要将模态呈现风格设置为Over Current Context，并将背景颜色设置为clear，以确保底层视图控制器在顶部呈现时仍然可见。

为了帮助大家，下面是我根据Jordan h的回答创建的一个快速扩展。它是用swift 5编写的，可以在Objective C中使用。

extension UIView {

    @objc func blurBackground(style: UIBlurEffect.Style, fallbackColor: UIColor) {
        if !UIAccessibility.isReduceTransparencyEnabled {
            self.backgroundColor = .clear

            let blurEffect = UIBlurEffect(style: style)
            let blurEffectView = UIVisualEffectView(effect: blurEffect)
            //always fill the view
            blurEffectView.frame = self.self.bounds
            blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

            self.insertSubview(blurEffectView, at: 0)
        } else {
            self.backgroundColor = fallbackColor
        }
    }

}

注意:如果你想在不影响文本的情况下模糊UILabel的背景，你应该创建一个容器UIView，将UILabel作为子视图添加到容器UIView，将UILabel的backgroundColor设置为UIColor。clear，然后调用blurBackground(style: UIBlurEffect。样式，fallbackColor: UIColor)的容器UIView。下面是用Swift 5写的一个简单的例子:

let frame = CGRect(x: 50, y: 200, width: 200, height: 50)
let containerView = UIView(frame: frame)
let label = UILabel(frame: frame)
label.text = "Some Text"
label.backgroundColor = UIColor.clear
containerView.addSubview(label)
containerView.blurBackground(style: .dark, fallbackColor: UIColor.black)

2019代码

下面是一个使用@AdamBardon技巧的更完整的例子。

@IBDesignable class ButtonOrSomethingWithBlur: UIButton {

    var ba: UIViewPropertyAnimator?
    private lazy var blurry: BlurryBall = { return BlurryBall() }()

    override func didMoveToSuperview() {
        super.didMoveToSuperview()
        
        // Setup the blurry ball.  BE SURE TO TEARDOWN.
        // Use superb trick to access the internal guassian level of Apple's
        // standard gpu blurrer per stackoverflow.com/a/55378168/294884
        
        superview?.insertSubview(blurry, belowSubview: self)
        ba = UIViewPropertyAnimator(duration:1, curve:.linear) {[weak self] in
            // note, those duration/curve values are simply unusued
            self?.blurry.effect = UIBlurEffect(style: .extraLight)
        }
        ba?.fractionComplete = live.largeplaybutton_blurfactor
    }
    
    override func willMove(toSuperview newSuperview: UIView?) {
        
        // Teardown for the blurry ball - critical
        
        if newSuperview == nil { print("safe teardown")
            ba?.stopAnimation(true)
            ba?.finishAnimation(at: .current)
        }
    }

    override func layoutSubviews() { super.layoutSubviews()
        blurry.frame = bounds, your drawing frame or whatever
    }

{题外话:作为一个通用的iOS工程问题，didMoveToWindow可能比didMoveToSuperview更适合你。其次，您可以使用其他一些方法来执行拆卸操作，但是拆卸操作就是这里显示的两行代码。

bluryball只是一个UIVisualEffectView。注意视觉效果视图的初始值。如果你碰巧需要圆角或者其他东西，在这门课上做吧。

class BlurryBall: UIVisualEffectView {
    
    override init(effect: UIVisualEffect?) { super.init(effect: effect)
        commonInit() }
    
    required init?(coder aDecoder: NSCoder) { super.init(coder: aDecoder)
        commonInit() }
    
    private func commonInit() {
        clipsToBounds = true
        backgroundColor = .clear
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        layer.cornerRadius = bounds.width / 2
    }
}