iOS 防录屏

//当用户录屏 怎么办 目前来说 只能进行提示。监听到就返回上一页，并弹出提示
1，检测当前设备是否在录屏：

pragma mark -- 录屏

• (void)addLuPingJianTing{
  //监测当前设备是否处于录屏状态
  UIScreen * sc = [UIScreen mainScreen];
  if (@available(iOS 11.0,*)) {
  if (sc.isCaptured) {
  NSLog(@"正在录制-----%d",sc.isCaptured);
  // 延迟三秒去执行
  dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.25 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
  [self.navigationController popViewControllerAnimated:YES];
  });
  // 延迟三秒去执行
  dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
  NormalAlartView view = [[[NSBundle mainBundle] loadNibNamed:@"NormalAlartView" owner:self options:nil] lastObject];
  view.isLuPing = YES;
  view.titleLabel.text = LocalizedString(@"为保护教程版权，请停止录屏操作！");
  view.sureBtn.hidden = YES;
  [view.cancleBtn setTitle:LocalizedString(@"我知道了") forState:(UIControlStateNormal)];
  [view show];
  });
  }
  }
  //ios11之后才可以录屏
  if (@available(iOS 11.0,)) {
  //检测设备
  [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(tipsVideoRecord) name:UIScreenCapturedDidChangeNotification object:nil];
  }
  }
  iOS 11.0之后 可以通过通知检测检测设备录屏
• (void)tipsVideoRecord {
  UIScreen * sc = [UIScreen mainScreen];
  if (@available(iOS 11.0,*)) {
  if (sc.isCaptured) {
  // 延迟三秒去执行
  dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
  NormalAlartView *view = [[[NSBundle mainBundle] loadNibNamed:@"NormalAlartView" owner:self options:nil] lastObject];
  view.isLuPing = YES;
  view.titleLabel.text = LocalizedString(@"为保护教程版权，请不要录屏！");
  view.sureBtn.hidden = YES;
  [view.cancleBtn setTitle:LocalizedString(@"我知道了") forState:(UIControlStateNormal)];
  [view show];
  });
  }
  }
  }