Find assets in library - add to a AVMutableComposition - export = crash - ios4

Question

I've been struggling with adding assets from the iPhone Photo Library to a AVMutableComposition and then export them. Here is what I got:
Finding the assets: (here I grab the AVURLAsset)
-(void) findAssets {
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
// Enumerate just the photos and videos group by using ALAssetsGroupSavedPhotos.
[library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
// Within the group enumeration block, filter to enumerate just videos.
[group setAssetsFilter:[ALAssetsFilter allVideos]];
[group enumerateAssetsUsingBlock:^(ALAsset *alAsset, NSUInteger index, BOOL *innerStop){
// The end of the enumeration is signaled by asset == nil.
if (alAsset) {
ALAssetRepresentation *representation = [alAsset defaultRepresentation];
NSURL *url = [representation url];
AVURLAsset *avAsset = [AVURLAsset URLAssetWithURL:url options:nil];
// Do something interesting with the AV asset.
[thumbs addObject:alAsset];
[assets addObject:avAsset];
}else if(alAsset == nil){
[self createScroll];
}
}];
}
failureBlock: ^(NSError *error) {
// Typically you should handle an error more gracefully than this.
NSLog(#"No groups");
}];
[library release];
}
Here I add a asset to my composition (I use the first object in the array for testing only.
-(void) addToCompositionWithAsset:(AVURLAsset*)_asset{
NSError *editError = nil;
composition = [AVMutableComposition composition];
AVURLAsset* sourceAsset = [assets objectAtIndex:0];
Float64 inSeconds = 1.0;
Float64 outSeconds = 2.0;
// calculate time
CMTime inTime = CMTimeMakeWithSeconds(inSeconds, 600);
CMTime outTime = CMTimeMakeWithSeconds(outSeconds, 600);
CMTime duration = CMTimeSubtract(outTime, inTime);
CMTimeRange editRange = CMTimeRangeMake(inTime, duration);
[composition insertTimeRange:editRange ofAsset:sourceAsset atTime:composition.duration error:&editError];
if (!editError) {
CMTimeGetSeconds (composition.duration);
}
}
And finally I export the comp and here it crashes
-(void)exportComposition {
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:composition presetName:AVAssetExportPresetPassthrough];
NSLog (#"can export: %#", exportSession.supportedFileTypes);
NSArray *dirs = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectoryPath = [dirs objectAtIndex:0];
NSString *exportPath = [documentsDirectoryPath stringByAppendingPathComponent:EXPORT_NAME];
[[NSFileManager defaultManager] removeItemAtPath:exportPath error:nil];
NSURL *exportURL = [NSURL fileURLWithPath:exportPath];
exportSession.outputURL = exportURL;
exportSession.outputFileType = AVFileTypeQuickTimeMovie;//#"com.apple.quicktime-movie";
[exportSession exportAsynchronouslyWithCompletionHandler:^{
NSLog (#"i is in your block, exportin. status is %d",
exportSession.status);
switch (exportSession.status) {
case AVAssetExportSessionStatusFailed:
case AVAssetExportSessionStatusCompleted: {
[self performSelectorOnMainThread:#selector (exportDone:)
withObject:nil
waitUntilDone:NO];
break;
}
};
}];
}
Does anyone have an idea of what it might be? It crashes on
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:composition presetName:AVAssetExportPresetPassthrough];
And I tried different presets and outputFileTypes.
Thanks
* SOLVED *

Answer 1

I have to answer my own question now when I have solved. It's amazing that I've been struggling with this for a whole day and then I fix it right after posting a question :)
I changed and moved:
composition = [AVMutableComposition
composition];
to:
composition = [[AVMutableComposition
alloc] init];
I think I was too tired when I was working on this yesterday. Thanks guys!