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
    }
}

Swift 3版本的凯文的答案返回模糊的图像-

func blurBgImage(image: UIImage) -> UIImage? {
        let radius: CGFloat = 20;
        let context = CIContext(options: nil);
        let inputImage = CIImage(cgImage: image.cgImage!);
        let filter = CIFilter(name: "CIGaussianBlur");
        filter?.setValue(inputImage, forKey: kCIInputImageKey);
        filter?.setValue("\(radius)", forKey:kCIInputRadiusKey);

        if let result = filter?.value(forKey: kCIOutputImageKey) as? CIImage{

            let rect = CGRect(origin: CGPoint(x: radius * 2,y :radius * 2), size: CGSize(width: image.size.width - radius * 4, height: image.size.height - radius * 4))

            if let cgImage = context.createCGImage(result, from: rect){
                return UIImage(cgImage: cgImage);
                }
        }
        return nil;
    }

你可以直接使用“带模糊的视觉效果视图”和“带模糊和活力的视觉效果视图”来创建背景模糊。

所有你需要做的是在iOS应用程序模糊背景…

在对象库中搜索“视觉效果模糊视图”

1 .图像

在你的故事板中拖动“带模糊的视觉效果视图”并设置它…

2 .图像

最后……你使你的应用程序背景模糊!

应用程序布局之前点击任何按钮!

应用程序视图后点击按钮，使整个应用程序背景模糊!

objective - c

UIVisualEffect *blurEffect;
blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];
UIVisualEffectView *visualEffectView;
visualEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
visualEffectView.frame = self.accessImageView.bounds;
[self.accessImageView addSubview:visualEffectView];

斯威夫特3.0

let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.dark)
let blurEffectView = UIVisualEffectView(effect: blurEffect)
blurEffectView.frame = view.bounds
blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
view.addSubview(blurEffectView)

来源:https://stackoverflow.com/a/24083728/4020910

这是乔伊回答的重要补充

这适用于你想用UINavigationController呈现一个模糊背景的UIViewController的情况。

// suppose you've done blur effect with your presented view controller
UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController];

// this is very important, if you don't do this, the blur effect will darken after view did appeared
// the reason is that you actually present navigation controller, not presented controller
// please note it's "OverFullScreen", not "OverCurrentContext"
nav.modalPresentationStyle = UIModalPresentationOverFullScreen;

UIViewController *presentedViewController = [[UIViewController alloc] init]; 
// the presented view controller's modalPresentationStyle is "OverCurrentContext"
presentedViewController.modalPresentationStyle = UIModalPresentationOverCurrentContext;

[presentingViewController presentViewController:nav animated:YES completion:nil];

享受吧!