iOS视频mp4转live实况图片

实况图片其实就是一张封面图和一个.mov视频，它们是通过一个identifier来关联起来的。

/// 给图片文件写入live信息
/// @param photoURL 图片地址
/// @param outputFile 输出地址
/// @param identifier identifier  =>   [[NSUUID UUID] UUIDString]
+ (BOOL)writeMetaDataByPath:(NSURL*)photoURL toPath:(NSString *)outputFile identify:(NSString *)identifier {
    NSMutableData *data = [NSData dataWithContentsOfURL:photoURL].mutableCopy;
    UIImage *image = [UIImage imageWithData:data];
    CGImageRef imageRef = image.CGImage;
    NSDictionary *imageMetadata = @{(NSString *)kCGImagePropertyMakerAppleDictionary : @{@"17" : identifier}};
    CGImageDestinationRef dest = CGImageDestinationCreateWithData((CFMutableDataRef)data, kUTTypeJPEG, 1, nil);
    CGImageDestinationAddImage(dest, imageRef, (CFDictionaryRef)imageMetadata);
    CGImageDestinationFinalize(dest);
    return [data writeToFile:outputFile atomically:YES];
}

// 成功block
typedef void(^VideoCompositionSuccess)(NSString *filePath);
// 失败block
typedef void(^VideoCompositionFail)(NSString *errorMsg);

/// 视频MP4转Mov，并写入identifier信息
/// @param sourcePath 视频源文件地址
/// @param outputPath 输出地址
/// @param identifier identifier =>  [[NSUUID UUID] UUIDString]
/// @param success 成功回调
/// @param fail 失败回调
- (void)mp4FileTransformToMovWithSourcePath:(NSString *)sourcePath outputPath:(NSString *)outputPath identifier:(NSString *)identifier success:(VideoCompositionSuccess)success fail:(VideoCompositionFail)fail {
    NSURL *sourceUrl = [NSURL fileURLWithPath:sourcePath];
    AVURLAsset *avAsset = [AVURLAsset URLAssetWithURL:sourceUrl options:nil];
    NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:avAsset];
    if ([compatiblePresets containsObject:AVAssetExportPresetHighestQuality]) {
        _exportSession = [[AVAssetExportSession alloc] initWithAsset:avAsset presetName:AVAssetExportPresetHighestQuality];
        AVMutableMetadataItem* item = [AVMutableMetadataItem metadataItem];
        item.keySpace = AVMetadataKeySpaceQuickTimeMetadata;
        item.key = AVMetadataQuickTimeMetadataKeyContentIdentifier;
        item.value = identifier;
        NSArray* metadata = [NSArray arrayWithObject:item];
        _exportSession.metadata = metadata;
        _exportSession.outputURL = [NSURL fileURLWithPath:outputPath];
        _exportSession.outputFileType = @"com.apple.quicktime-movie";//AVFileTypeQuickTimeMovie;
        _exportSession.shouldOptimizeForNetworkUse = YES;
        
        //如有此文件则直接返回
        if ([[NSFileManager defaultManager] fileExistsAtPath:outputPath]) {
            if (success) {
                success(outputPath);
            }
            return;
        }
        __block AVAssetExportSession *weakSession = _exportSession;
        [_exportSession exportAsynchronouslyWithCompletionHandler:^(void) {
             switch (weakSession.status) {
                 case AVAssetExportSessionStatusUnknown: {
                     break;
                 }
                 case AVAssetExportSessionStatusWaiting: {
                     break;
                 }
                 case AVAssetExportSessionStatusExporting: {
                     
                     break;
                 }
                 case AVAssetExportSessionStatusCompleted: {
                     NSLog(@"mov file size:%lf MB",[NSData dataWithContentsOfURL:weakSession.outputURL].length/1024.f/1024.f);
                     NSData *da = [NSData dataWithContentsOfFile:outputPath];
                     NSLog(@"da:%lu",(unsigned long)da.length);
                     if (success) {
                         success(outputPath);
                     }
                 }
                     break;
                     
                 case AVAssetExportSessionStatusFailed: {
                     if (fail) {
                         fail(@"视频格式转换出错");
                     }
                 }
                     break;
                     
                 case AVAssetExportSessionStatusCancelled: {
                     if (fail) {
                         fail(weakSession.error.localizedDescription);
                     }
                 }
                     break;
             }
         }];
    }
}

/// 把有live信息的图片和.mov视频保存到相册
#import <Photos/Photos.h>

NSURL *photo = [NSURL fileURLWithPath:finalCoverPath];
NSURL *video = [NSURL fileURLWithPath:finalVideoPath];
[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
    PHAssetCreationRequest *request = [PHAssetCreationRequest creationRequestForAsset];
    [request addResourceWithType:PHAssetResourceTypePhoto fileURL:photo options:nil];
    [request addResourceWithType:PHAssetResourceTypePairedVideo fileURL:video options:nil];
} completionHandler:^(BOOL success, NSError * _Nullable error) {
    if (success) {
        dispatch_async(dispatch_get_main_queue(), ^{
           [BaseProgressHUD showMiddleInfoText:@"已保存到相册" inView:nil];
        });
    }else {
        dispatch_async(dispatch_get_main_queue(), ^{
           [BaseProgressHUD showMiddleInfoText:@"保存失败，请重试" inView:nil];
    });
}}];