iOS8毛玻璃效果

  UIBlurEffect*blueEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
    UIVisualEffectView* visualView=[[UIVisualEffectView alloc]initWithEffect:blueEffect];
     visualView.frame = self.tabBar.frame;
     [self.tabBar insertSubview:visualView atIndex:];