= self.
scanView.frame.origin.y;  CGFloat 
scanImageViewW = self.
scanViewWidth.constant;  CGFloat 
scanImageViewH = 
7  _scanImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@
"scanLine"]]  _scanImageView.frame = CGRectMake(
scanImageViewX, scanImageViewY, scanImageViewW, scanImageViewH);  [self.
scanView addSubview:_scanImageView];  [UIView animateWithDuration:
2.
0 delay:
0 options:UIViewAnimationOptionRepeat animations:^{      _scanImageView.frame = CGRectMake(
scanImageViewX, scanImageViewY + self.
scanViewHeight.constant, scanImageViewW, scanImageViewH);  } completion:nil]}
四、具体代码