typedef NS_ENUM(NSInteger, UIBlurEffectStyle) {   
    UIBlurEffectStyleExtraLight,   
    UIBlurEffectStyleLight,   
    UIBlurEffectStyleDark   
} NS_ENUM_AVAILABLE_IOS(8_0);   
   
   
    UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];   
    UIVisualEffectView *blurEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];   
    blurEffectView.frame = self.imageView.bounds;   
    [self.imageView insertSubview:blurEffectView atIndex:0];