我正在尝试从保存在 Documents/ 文件夹中的视频中获取视频缩略图,并将其显示在 UITableViewCell 内的 UIImageView 中。这是我获取缩略图的功能:
- (UIImage*) thumbnailImageForVideo:(NSURL *)sourceURL
{
AVAsset *asset = [AVAsset assetWithURL:sourceURL];
AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc]initWithAsset:asset];
NSError *err = NULL;
CMTime time = CMTimeMake(1, 1);
CGImageRef imageRef = [imageGenerator copyCGImageAtTime:time actualTime:NULL error:&err];
NSLog(@"err==%@, imageRef==%@", err, imageRef);
UIImage *thumbnail = [[UIImage alloc] initWithCGImage:imageRef];
CGImageRelease(imageRef); // CGImageRef won't be released by ARC
return thumbnail;
}
这是我使用它的地方:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
LibraryCell *libraryCell = [tableView dequeueReusableCellWithIdentifier:@"LibraryCell" forIndexPath:indexPath];
NSString *videoPath = [NSString stringWithFormat:@"%@/%@", [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"], [libraryFiles objectAtIndex:indexPath.item]];
libraryCell.itemImage.image = [self thumbnailImageForVideo:[NSURL URLWithString:videoPath]];
return libraryCell;
}
该应用程序不会崩溃,但没有图像。这是我在控制台中看到的:
2013-04-13 23:44:46.828 GeekOut[14433:907] err==Error Domain=NSURLErrorDomain Code=-1 "unknown error" UserInfo=0x1f0b4610 {NSUnderlyingError=0x1f0b3220 "The operation couldn’t be completed. (OSStatus error -12935.)", NSLocalizedDescription=unknown error}, imageRef==(null)
2013-04-13 23:44:46.859 GeekOut[14433:907] err==Error Domain=NSURLErrorDomain Code=-1 "unknown error" UserInfo=0x1dd8c660 {NSUnderlyingError=0x1dd8c5c0 "The operation couldn’t be completed. (OSStatus error -12935.)", NSLocalizedDescription=unknown error}, imageRef==(null)
2013-04-13 23:44:46.893 GeekOut[14433:907] err==Error Domain=NSURLErrorDomain Code=-1 "unknown error" UserInfo=0x1f0bec80 {NSUnderlyingError=0x1f0be9b0 "The operation couldn’t be completed. (OSStatus error -12935.)", NSLocalizedDescription=unknown error}, imageRef==(null)