iphone - [NSMutableArray objectAtIndex:]：索引 0 超出 AVURLAsset 中空数组的界限

Question

我尝试使用以下代码合并音频。

AVMutableComposition* composition = [AVMutableComposition composition];
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:audioURL options:nil];
AVURLAsset* audioAsset1 = [[AVURLAsset alloc]initWithURL:audioURL1 options:nil];
AVURLAsset* audioAsset2 = [[AVURLAsset alloc]initWithURL:audioURL1 options:nil];
AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
NSError* error = NULL;
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero,videoAsset.duration) 
                                       ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo]objectAtIndex:0] 
                                        atTime:kCMTimeZero  
AVMutableCompositionTrack *compositionAudioTrack1 = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
        [compositionAudioTrack1 insertTimeRange:CMTimeRangeMake(kCMTimeZero,audioAsset1.duration) 
                                       ofTrack:[[audioAsset1 tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0] 
                                        atTime:kCMTimeZero
                                         error:&error];
AVMutableCompositionTrack *compositionAudioTrack2 = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
        [compositionAudioTrack2 insertTimeRange:CMTimeRangeMake(kCMTimeZero,audioAsset2.duration) 
                                       ofTrack:[[audioAsset2 tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0] 
                                        atTime:kCMTimeZero
                                         error:&error];

当我尝试执行“[[audioAsset1 trackingWithMediaType:AVMediaTypeAudio]objectAtIndex:0]”时，出现以下错误

*** Terminating app due to uncaught exception 'NSRangeException', 
reason: '*** -[NSMutableArray objectAtIndex:]: index 0 beyond bounds for empty array'

但是当我尝试在控制台中打印 audioAsset1 时，它正在打印“<AVURLAsset: 0x198920, URL = 'path'>”。我检查了路径，那个文件在那里。

我的错误是什么？请帮我解决它。

Answer 1

我解决了这个问题；

只是我已经替换了以下语句

NSURL *audioURL = [NSURL URLWithString:path];
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:audioURL options:nil]

带有以下声明

NSURL *audioURL = [NSURL fileURLWithPath:path]
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:audioURL options:nil]

谢谢。