第一种方法：

UIBlurEffect *effect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];   UIVisualEffectView *effectView = [[UIVisualEffectView alloc] initWithEffect:effect];   effectView.alpha = 0.9;   effectView.frame = CGRectMake(0, 0, bgImageView.frame.size.width, bgImageView.frame.size.height);[bgImageView addSubview:effectView];

 

第二种方法：

UIToolbar *toolbar = [[UIToolbaralloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT)];   toolbar.barStyle = UIBarStyleDefault;[_backImg addSubview:toolbar];