AVAssetTrack 在 iOS 7 中组合视频不好

Question

我可以在 iOS 6 中成功地将 2 个视频合并为 1 个。但我不知道在 iOS 7 中会发生什么。我遇到了这样的数组错误。

由于未捕获的异常 'NSRangeException' 导致应用程序终止，原因：'* -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array'

这是我编写的代码的一部分。我已经在代码中显示了哪里错误。我该怎么办？

NSMutableArray *array = [[NSMutableArray alloc]init ];

for(int kk=0;kk < trackRecordingVideoName+1; kk++)
{
    [array addObject:[[self userPath] stringByAppendingPathComponent:[NSString stringWithFormat:@"%@%d.mp4",recordingVideoName,kk]]];
    NSLog(@"%d is added",kk);
}

videoPathArray= [[NSArray alloc]initWithArray:array];
[videoPathArray retain];


AVMutableComposition *composition = [AVMutableComposition composition];

AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];


CMTime startTime = kCMTimeZero;


NSLog(@"videoPathArray.count is %d",videoPathArray.count);
for (NSInteger i=0; i < videoPathArray.count; i++) {

    NSLog(@"For loop now is %d and name is %@",i,[videoPathArray objectAtIndex:i]);
    NSString *path = (NSString*)[videoPathArray objectAtIndex:i];

    NSURL *url = [[NSURL alloc] initFileURLWithPath:path];

    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:url options:nil];

    [url release];

    //*************************************
    AVAssetTrack *videoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];//This is the error
    //*************************************


    if(i == 0)
    {
        [compositionVideoTrack setPreferredTransform:videoTrack.preferredTransform];
    }

    Boolean ok = [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:videoTrack atTime:startTime error:nil];

    if(ok)
    {NSLog(@"can combine in for loop");}
    else{NSLog(@"cannot combine in for loop");}

    startTime = CMTimeAdd(startTime, [asset duration]);
}

Answer 1

检查url是否正确，它应该指向一个真实的视频文件，你的AVURLAsset不包含任何视频媒体类型。