UIVisualEffectView 對(duì)象提供了一種簡(jiǎn)單的方法實(shí)現(xiàn)一些復(fù)雜的視覺效果

使用注意：

如果想對(duì)其增加子視圖時(shí)候，不應(yīng)該直接添加子視圖到 UIVisualEffectView視圖中，而是添加到 UIVisualEffectView 對(duì)象的 contentView 中

Simulator Screen Shot 2016年3月19日 下午10.35.32.png

import UIKit

class ViewController: UIViewController {
    
    var imageView:UIImageView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        imageView = UIImageView(frame: self.view.bounds)
        imageView.image = UIImage(named: "imageName")
        imageView.contentMode = .ScaleAspectFill //圖片適配樣式
        imageView.userInteractionEnabled = true //用戶交互
        let tapGestureRecognizer = UISwipeGestureRecognizer(target: self, action: "swipeEvent")
        imageView.addGestureRecognizer(tapGestureRecognizer) //增加滑動(dòng)手勢(shì)
        self.view.addSubview(imageView)  
    }

    func swipeEvent() {
        
        let blurEffect = UIBlurEffect(style: .Light) // 模糊樣式
        let effectView = UIVisualEffectView(effect: blurEffect)
        effectView.frame = CGRect(x: 0, y: 0, width: imageView.frame.width/2, height: self.view.frame.height)
        imageView.addSubview(effectView)
    }
}