iOS防止用户截屏

NSOperationQueue *mainQueue = [NSOperationQueuemainQueue];    [[NSNotificationCenterdefaultCenter]addObserverForName:UIApplicationUserDidTakeScreenshotNotification                                                       object:nilqueue:mainQueueusingBlock:^(NSNotification *note){                [selfjiePing];         }];-(void)jiePing{    UIAlertView *alertView=[[UIAlertViewalloc]initWithTitle:nilmessage:@"[安全提醒]内含付款码，只适合当面使用。不要截图或分享给他人以保障资金安全。"delegate:selfcancelButtonTitle:@"绝不给别人"otherButtonTitles:@"仅我自己用",nil];    alertView.tag=105;    [alertView show];    }//这种写法会导致整个程序任何一个界面截图都会有弹出提示框，因为根本就没有指定哪个控制器，而且是一直在主线程里面NSOperationQueue *mainQueue = [NSOperationQueuemainQueue];  [[NSNotificationCenter defaultCenter]addObserver:selfselector:@selector(jiePing)name:UIApplicationUserDidTakeScreenshotNotification  object:nil];  //这个写法是针对于当前控制器离开当前控制器的时候  最好移除通知 [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector( jiePing) object:nil];    [[NSNotificationCenter defaultCenter] removeObserver:selfname:UIApplicationUserDidTakeScreenshotNotification object:nil];

原文链接：http://blog.csdn.net/ios_xumin/article/details/51788544