iOS 实现毛玻璃效果的简单方式

iOS提供了UIBlurEffect来快速实现毛玻璃效果，并提供了几种Style可供选择

// 承载效果的view；
UIView *testView = [[UIView alloc] initWithFrame:self.bounds];
// 毛玻璃效果的style
UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleExtraLight];
// 毛玻璃视图
UIVisualEffectView *visualView = [[UIVisualEffectView alloc]initWithEffect:blurEffect];
visualView.frame = self.bounds;
// addSubview
[testView addSubview:visualView];

style可选择枚举如下，iOS13后更丰富了可选样式

typedef NS_ENUM(NSInteger, UIBlurEffectStyle) {
    /* Traditional blur styles.
     */
    UIBlurEffectStyleExtraLight,
    UIBlurEffectStyleLight,
    UIBlurEffectStyleDark,
    UIBlurEffectStyleExtraDark API_AVAILABLE(tvos(10.0)) API_UNAVAILABLE(ios) API_UNAVAILABLE(watchos),

    /* Styles which automatically show one of the traditional blur styles,
     * depending on the user interface style.
     *
     * Regular displays either Light or Dark.
     */
    UIBlurEffectStyleRegular API_AVAILABLE(ios(10.0)),
    /* Prominent displays either ExtraLight, Dark (on iOS), or ExtraDark (on tvOS).
     */
    UIBlurEffectStyleProminent API_AVAILABLE(ios(10.0)),

    /*
     * Blur styles available in iOS 13.
     *
     * Styles which automatically adapt to the user interface style:
     */
    UIBlurEffectStyleSystemUltraThinMaterial        API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemThinMaterial             API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemMaterial                 API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemThickMaterial            API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemChromeMaterial           API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),

    /* And always-light and always-dark versions:
     */
    UIBlurEffectStyleSystemUltraThinMaterialLight   API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemThinMaterialLight        API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemMaterialLight            API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemThickMaterialLight       API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemChromeMaterialLight      API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),

    UIBlurEffectStyleSystemUltraThinMaterialDark    API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemThinMaterialDark         API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemMaterialDark             API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemThickMaterialDark        API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos),
    UIBlurEffectStyleSystemChromeMaterialDark       API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(watchos) API_UNAVAILABLE(tvos)

} API_AVAILABLE(ios(8.0));