Question

我一直在尝试从我从parse.com查询的视频中设置缩略图但没有运气。这是我的缩略图代码：

- (UIImage *)thumbnailFromVideoAtURL:(NSURL *)url
    {
    AVAsset *asset = [AVAsset assetWithURL:url];

    //  Get thumbnail at the very start of the video
    CMTime thumbnailTime = [asset duration];
    thumbnailTime.value = 0;

    //  Get image from the video at the given time
    AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
    imageGenerator.appliesPreferredTrackTransform = YES;

    CGImageRef imageRef = [imageGenerator copyCGImageAtTime:thumbnailTime actualTime:NULL error:NULL];
    UIImage *thumbnail = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);

    return thumbnail;
}

它适用于普通视图控制器中的viewDidLoad，但我不知道如何在单元格的UITableViewController中设置它。有人能指出我正确的方向吗？

Answer 1

在UITableViewDataSource协议实施中：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

NSString *cellIdentifier = @"yourellIdentifier";

CustomCell *cell = [tableView dequeueReusableCellWithIdentifier: cellIdentifier];

NSURL* videoURL = videos[indexPath.row];

...
[cell loadPhotoFromURL: videoURL];
...

 return cell;
}

您必须实现自定义单元格：

CustomCell.h

@interface CustomCell : UITableViewCell

@property (weak, nonatomic) IBOutlet UIImageView *thumbnaliImageView;

CustomCell.m

#pragma mark - thumbnal loading
- (void)loadPhotoFromURL:(NSURL*)url
{
    [self.thumbnaliImageView  setBackgroundColor:[UIColor whiteColor]];
    UIImage *image = [UIImage imageNamed:@"Stub"];
    self.thumbnaliImageView.image = image;
    self.thumbnaliImageView.contentMode = UIViewContentModeScaleAspectFit;


    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void) {


     AVAsset *asset = [AVAsset assetWithURL:url];

    //  Get thumbnail at the very start of the video
    CMTime thumbnailTime = [asset duration];
    thumbnailTime.value = 0;

    //  Get image from the video at the given time
    AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
    imageGenerator.appliesPreferredTrackTransform = YES;

    CGImageRef imageRef = [imageGenerator copyCGImageAtTime:thumbnailTime actualTime:NULL error:NULL];
    UIImage *thumbnail = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);

        if(thumbnail){
            // do UI stuff back in UI land
            dispatch_async(dispatch_get_main_queue(), ^{

                self.thumbnaliImageView.image = thumbnail;

            });

        }
    });

}

}

Answer 2

使用CustomCell

 static NSString *CellIdentifier = @"Cell";
    CustomCell *cell;
    if(indexPath.row != [Array count] )
    {
       cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
        if (cell == nil)
        {
            cell = [[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:nil];
        }

        NSString *imageurl = [NSString stringWithFormat:@"%@",[[arraysearchVideoList objectAtIndex:indexPath.row] valueForKey:@"imageUrl"]];
        [cell.ImageView setImageWithURL:[NSURL URLWithString:imageurl]
                       placeholderImage:[UIImage imageNamed:@"noimage.png"]];
        [cell.ImageView addSubview:image];

Answer 3

你可以这样做，在其中创建自定义单元格，以提供imageview标记并且在表格的cellForRowAtIndexPath方法中应用此代码：

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

        static NSString *CellIdentifier1;
        CellIdentifier1 = @"contactList";

        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier1];

        if (cell == nil) {
            NSArray *ar = [[NSBundle mainBundle] loadNibNamed:@"CCell" owner:self options:nil];
            cell = [ar objectAtIndex:1];

        }
    UIImageView *imgContact = (UIImageView*)[cell viewWithTag:TAG_CONTACTIMAGE]
     imgContact.image = [self thumbnailFromVideoAtURL:url];
    }

如何在单元格中设置视频的缩略图图像

3 个答案: