swift4.0-为视图添加模糊效果

UIVisualEffect两个子类UIBlurEffect和UIVibrancyEffect

UIBlurEffect表模糊的一个类，传入UIBlurEffectStyle类型的值来决定创建怎么样的模糊效果
UIVibrancyEffect会显示后面涂层的颜色

UIBlurEffectStyle是一个枚举类型

public enum UIBlurEffectStyle : Int {
    case extraLight
    case light
    case dark
}

UIVisualEffectView 用来接收UIVisualEffect类型的视觉效果

使用UIBlurEffect创建的模糊效果

UIBlurEffect@2x.png

代码如下

    func blurEffct() -> Void {
        let visualEffect = UIBlurEffect(style: .dark)
        
        let blurView = UIVisualEffectView(effect: visualEffect)
        blurView.alpha = 0.5
        blurView.frame = CGRect(x: 0, y: 0, width: 200, height: 200)
        
        imgView.addSubview(blurView)
    }

使用UIVibrancyEffect创建的模糊效果

UIVibrancyEffect@2x.png

代码如下：

    func vibrancyEffct() -> Void {
        let txtLable = UILabel()
        txtLable.frame = CGRect(x: 0, y: 0, width: 200, height: 50)
        txtLable.text = "shine blur something"
        txtLable.textColor = UIColor.red //无效
        txtLable.tintColor = UIColor.red
        txtLable.font = UIFont.boldSystemFont(ofSize: 20)
        
        
        let visualEffect = UIBlurEffect(style: .extraLight)
        let vibrancyEffct = UIVibrancyEffect(blurEffect: visualEffect)
        
        let blurView = UIVisualEffectView(effect: vibrancyEffct)
        blurView.frame = CGRect(x: 0, y: 0, width: 200, height: 200)
        blurView.alpha = 0.5
        blurView.contentView.addSubview(txtLable) //必须添加到contentView
        
        imgView.addSubview(blurView)
    }

UIBlurEffect直接对imgView视图进行模糊，vibrancyEffct是对添加到imgView上的txtLable视图进行模糊