iOS两个音频合并

//选择第一个asset

- (IBAction)loadAssetOne:(UIButton *)sender {

    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeSavedPhotosAlbum] == NO) {

        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"No Saved Album Found"

                                                      delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

        [alert show];

    } else {

        isSelectingAssetOne = TRUE;

        [self startMediaBrowserFromViewController:self usingDelegate:self];

    }

}

//选择第二个asset

- (IBAction)loadAssetTwo:(UIButton *)sender {

    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeSavedPhotosAlbum] == NO) {

        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"No Saved Album Found"

                                                      delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

        [alert show];

    } else {

        isSelectingAssetOne = FALSE;

        [self startMediaBrowserFromViewController:self usingDelegate:self];

    }

}

- (IBAction)mergeAndSave:(UIButton *)sender {

    if (firstAsset !=nil && secondAsset!=nil) {

        // 1 - Create AVMutableComposition object. This object will hold your AVMutableCompositionTrack instances.

        //创建一个AVMutableComposition实例

        AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];

        // 2 - Video track

        //创建一个轨道,类型是AVMediaTypeAudio

        AVMutableCompositionTrack *firstTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio

                                                                            preferredTrackID:kCMPersistentTrackID_Invalid];

        //获取firstAsset中的音频,插入轨道

        [firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, firstAsset.duration)

                            ofTrack:[[firstAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:kCMTimeZero error:nil];

        //获取secondAsset中的音频,插入轨道

        [firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, secondAsset.duration)

                            ofTrack:[[secondAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:firstAsset.duration error:nil];

        // 4 - Get path

        //创建输出路径

        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

        NSString *documentsDirectory = [paths objectAtIndex:0];

        NSString *myPathDocs =  [documentsDirectory stringByAppendingPathComponent:

                                [NSString stringWithFormat:@"mergeVideo-%d.mov",arc4random() % 1000]];

        NSURL *url = [NSURL fileURLWithPath:myPathDocs];

        // 5 - Create exporter

        //创建输出对象

        AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition

                                                                          presetName:AVAssetExportPresetHighestQuality];

        exporter.outputURL=url;

        exporter.outputFileType = AVFileTypeQuickTimeMovie;

//        @"com.apple.quicktime-movie";

        exporter.shouldOptimizeForNetworkUse = YES;

        [exporter exportAsynchronouslyWithCompletionHandler:^{

            dispatch_async(dispatch_get_main_queue(), ^{

                [self exportDidFinish:exporter];

            });

        }];

    }

}

-(void)exportDidFinish:(AVAssetExportSession*)session {

    NSLog(@"%ld",session.status);

    if (session.status == AVAssetExportSessionStatusCompleted) {

        NSURL *outputURL = session.outputURL;

        MPMoviePlayerViewController *theMovie = [[MPMoviePlayerViewController alloc]

                                                initWithContentURL:outputURL];

        [self presentMoviePlayerViewControllerAnimated:theMovie];

    }

    audioAsset = nil;

    firstAsset = nil;

    secondAsset = nil;

}

-(BOOL)startMediaBrowserFromViewController:(UIViewController*)controller usingDelegate:(id)delegate {

    // 1 - Validation

    if (([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeSavedPhotosAlbum] == NO)

        || (delegate == nil)

        || (controller == nil)) {

        return NO;

    }

    // 2 - Create image picker

    UIImagePickerController *mediaUI = [[UIImagePickerController alloc] init];

    mediaUI.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;

    mediaUI.mediaTypes = [[NSArray alloc] initWithObjects:(NSString *)kUTTypeMovie, nil];

    // Hides the controls for moving & scaling pictures, or for

    // trimming movies. To instead show the controls, use YES.

    mediaUI.allowsEditing = YES;

    mediaUI.delegate = delegate;

    // 3 - Display image picker

    [controller presentModalViewController: mediaUI animated: YES];

    return YES;

}

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

    // 1 - Get media type

    NSString *mediaType = [info objectForKey: UIImagePickerControllerMediaType];

    // 2 - Dismiss image picker

    [self dismissModalViewControllerAnimated:NO];

    // 3 - Handle video selection

    //判断是不是选中的第一个asset,分别加载到2个asset

    if (CFStringCompare ((__bridge_retained CFStringRef) mediaType, kUTTypeMovie, 0) == kCFCompareEqualTo) {

        if (isSelectingAssetOne){

            NSLog(@"Video One  Loaded");

            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Asset Loaded" message:@"Video One Loaded"

                                                          delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

            [alert show];

            firstAsset = [AVAsset assetWithURL:[info objectForKey:UIImagePickerControllerMediaURL]];

        } else {

            NSLog(@"Video two Loaded");

            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Asset Loaded" message:@"Video Two Loaded"

                                                          delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

            [alert show];

            secondAsset = [AVAsset assetWithURL:[info objectForKey:UIImagePickerControllerMediaURL]];

        }

    }

}