关于模态弹窗点击灰色区域消失

标题是不是写的很有诗意？我自己也觉得有点儿迷糊，其实就是这样需求:模态弹出来的窗口，需要点击窗口以外的区域，也就是模态区域让这个窗口消失。一般这种场景会出现在iPad里，当你modalPresentationStyle为UIModalPresentationFormSheet时，会有这种需求。网上找了一下，这种东东还真能实现，于是想着UIAlertView是不是也可以实现呢？你猜咋地，竟然真的可以。

其实原理就是在弹框给那个view的window注册一个点击事件，然后在点击事件里判断点击区域是不是模态区域，具体代码如下：

- (IBAction)showAlert:(id)sender {  alert = [[UIAlertView alloc] initWithTitle:@"模态测试"                                     message:@"请点击四周的模态区域我就消失"                                    delegate:nil                           cancelButtonTitle:@"确定"                           otherButtonTitles:nil];  [alert show];  recognizerTap = [[UITapGestureRecognizer alloc] initWithTarget:self                                                          action:@selector(handleTapBehind:)];   [recognizerTap setNumberOfTapsRequired:1];  recognizerTap.cancelsTouchesInView = NO;  [alert.window addGestureRecognizer:recognizerTap];}- (void)handleTapBehind:(UITapGestureRecognizer *)sender{  if (sender.state == UIGestureRecognizerStateEnded){    CGPoint location = [sender locationInView:nil];    if (![alert pointInside:[alert convertPoint:location fromView:alert.window] withEvent:nil]){      [alert.window removeGestureRecognizer:sender];      [alert dismissWithClickedButtonIndex:0                                  animated:YES];    }  }}