仿微信图片预览

   SYPicturePreviewView *previewImageView = [[SYPicturePreviewView alloc] initWithFrame:[UIScreen mainScreen].bounds];
   previewImageView.allImages = previewImages; // 需要预览的所有图片对象
   //ImageCollectionViewCell *cell1 = (ImageCollectionViewCell *)[collectionView cellForItemAtIndexPath:indexPath];
  // CGRect rect = [cell1.contentView.superview convertRect:cell1.contentView.frame toView:[UIApplication sharedApplication].keyWindow];
// 传入点击图片的位置
   [previewImageView showWithFristImage:cell1.imageView.image fromIndex:indexPath.row fromRect:rect];
   previewImageView.delegate = self; // 实现代理

#pragma SYPicturePreviewViewDelegate
- (CGRect)disMisWithIndex:(NSInteger)index view:(SYPicturePreviewView *)view{
  // NSIndexPath *path = [NSIndexPath indexPathForRow:index inSection:0];
   // ImageCollectionViewCell *cell1 = (ImageCollectionViewCell *)[self.collectionView cellForItemAtIndexPath:path];
   //CGRect toRect = [cell1.contentView.superview convertRect:cell1.contentView.frame toView:[UIApplication sharedApplication].keyWindow];
   return toRect; //返回点击图片对应的消失位置
}