Unable to trim a video using AVAssetExportSession - iphone

Question

I want to trim a video:
-(void)trimVideo:(NSURL*)outputURL
{
//[[NSFileManager defaultManager] removeItemAtURL:outputURL error:nil];
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:outputURL options:nil];
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPresetLowQuality];
NSString * outputFilePath = NSHomeDirectory();
outputFilePath = [outputFilePath stringByAppendingPathComponent:#"Library"];
outputFilePath = [outputFilePath stringByAppendingPathComponent:#"temp.mov"];
NSURL * outputFileUrl = [NSURL fileURLWithPath:outputFilePath];
exportSession.outputURL = outputFileUrl;
exportSession.shouldOptimizeForNetworkUse = YES;
exportSession.outputFileType = AVFileTypeMPEG4;
CMTime start = CMTimeMakeWithSeconds(1.0, 600);
CMTime duration = CMTimeMakeWithSeconds(3.0, 600);
CMTimeRange range = CMTimeRangeMake(start, duration);
exportSession.timeRange = range;
[exportSession exportAsynchronouslyWithCompletionHandler:^(void)
{
NSLog(#"Export Complete %d %#", exportSession.status, exportSession.error);
//[exportSession release];
}];
}
But I get the error:
Export Complete 4 Error Domain=AVFoundationErrorDomain Code=-11823 "Cannot Save" UserInfo=0x2008f420 {NSLocalizedRecoverySuggestion=Try saving again., NSLocalizedDescription=Cannot Save}
Not exactly sure how to resolve.

Answer 1

This did the trick:
-(void)trimVideo:(NSURL*)videoToTrimURL
{
//[[NSFileManager defaultManager] removeItemAtURL:outputURL error:nil];
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:videoToTrimURL options:nil];
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPresetHighestQuality];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *outputURL = paths[0];
NSFileManager *manager = [NSFileManager defaultManager];
[manager createDirectoryAtPath:outputURL withIntermediateDirectories:YES attributes:nil error:nil];
outputURL = [outputURL stringByAppendingPathComponent:#"output.mp4"];
// Remove Existing File
[manager removeItemAtPath:outputURL error:nil];
exportSession.outputURL = [NSURL fileURLWithPath:outputURL];
exportSession.shouldOptimizeForNetworkUse = YES;
exportSession.outputFileType = AVFileTypeQuickTimeMovie;
CMTime start = CMTimeMakeWithSeconds(1.0, 600);
CMTime duration = CMTimeMakeWithSeconds(3.0, 600);
CMTimeRange range = CMTimeRangeMake(start, duration);
exportSession.timeRange = range;
[exportSession exportAsynchronouslyWithCompletionHandler:^(void)
{
switch (exportSession.status) {
case AVAssetExportSessionStatusCompleted:
[self writeVideoToPhotoLibrary:[NSURL fileURLWithPath:outputURL]];
NSLog(#"Export Complete %d %#", exportSession.status, exportSession.error);
break;
case AVAssetExportSessionStatusFailed:
NSLog(#"Failed:%#",exportSession.error);
break;
case AVAssetExportSessionStatusCancelled:
NSLog(#"Canceled:%#",exportSession.error);
break;
default:
break;
}
//[exportSession release];
}];
}