转自:http://blog.csdn.net/qq_30963589/article/details/50580872
+(UIView*)addCoverView{ UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height)]; view.backgroundColor = [UIColor blackColor]; view.alpha = 0.5; [[UIApplication sharedApplication].keyWindow addSubview:view]; return view; } +(void)removeCoverView:(UIView*)view{ [view removeFromSuperview]; }