ios - 如何使用 CloudKit API 将 PHLivePhoto 保存到 iCloud

Question

现在我正在使用以下代码。但是发生了一些奇怪的事情。

PHLivePhoto *livePhoto = .....;

NSString *fileName = [[NSProcessInfo processInfo] globallyUniqueString];
NSURL *url = [NSURL fileURLWithPath: NSTemporaryDirectory()];
url = [url URLByAppendingPathComponent: fileName];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject: livePhoto];
[data writeToURL: url atomically: YES];

CKAsset *asset = [[CKAsset alloc] initWithFileURL: url];

然后使用CKModifyRecordsOperation将该 Assets 保存到iCloud，然后取回。

NSData *data = [NSData dataWithContentsOfURL: fetchedAsset.fileURL];
PHLivePhoto *thePhoto = [NSKeyedUnarchiver unarchiveObjectWithData: data];
PHLivePhotoView *photoView = ......;
photoView.livePhoto = thePhoto;

大部分都有效，除了当 photoView 停止播放时，photoView 的图像就消失了。如果我再次长按它，它就会正常播放。

为什么会这样？

Answer 1

NSKeyedArchiver 似乎没有按预期保存实时照片。作为解决方案之一，您应该拆解PHLivePhoto并分别检索视频和静态图像，然后将它们上传到iCloud:

#import <Photos/Photos.h>
#import <CloudKit/CloudKit.h>
#import <MobileCoreServices/MobileCoreServices.h>

+ (void) disassembleLivePhoto:(nonnull PHLivePhoto*)livePhoto completion:(void (^__nonnull)(UIImage * _Nullable stillImage, AVURLAsset * _Nullable video, NSURL* _Nullable imageURL, NSURL* _Nullable videoURL))block
{
    NSArray<PHAssetResource*>* resources = [PHAssetResource assetResourcesForLivePhoto:livePhoto];

    __block PHAssetResource *resImage = nil, *resVideo = nil;
    NSString *fileName = [[NSUUID UUID] UUIDString];
    NSURL *urlMov = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent:[fileName stringByAppendingPathExtension:@"mov"]]];
    NSURL *urlImg = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent:[fileName stringByAppendingPathExtension:@"jpg"]]];

    [resources enumerateObjectsUsingBlock:^(PHAssetResource * _Nonnull res, NSUInteger idx, BOOL * _Nonnull stop) {
        if (res.type == PHAssetResourceTypePairedVideo){
            resVideo = res;
        } else if (res.type == PHAssetResourceTypePhoto){
            resImage = res;
        }
    }];

    [[PHAssetResourceManager defaultManager] writeDataForAssetResource:resVideo toFile:urlMov options:nil completionHandler:^(NSError * _Nullable error) {    
        [[PHAssetResourceManager defaultManager] writeDataForAssetResource:resImage toFile:urlImg options:nil completionHandler:^(NSError * _Nullable error) {
            block([UIImage imageWithData:[NSData dataWithContentsOfURL:urlImg]], [AVURLAsset assetWithURL:urlMov], urlImg, urlMov);
        }];
    }];
}

- (void) sendLivePhotoComponentsWithImageURL:(nonnull NSURL*)urlImage videoURL:(nonnull NSURL*)urlVideo completionBlock:(void(^ __nonnull)(CKRecord* __nullable recordLivePhoto))block
{    
    CKAsset *assetVideo = [[CKAsset alloc] initWithFileURL:urlVideo];
    CKAsset *assetImage = [[CKAsset alloc] initWithFileURL:urlImage];

    CKContainer *ckcContainer = [CKContainer defaultContainer];
    CKDatabase *ckdbPublic = [ckcContainer publicCloudDatabase];    // in this example I use public DB

    [ckcContainer fetchUserRecordIDWithCompletionHandler:^(CKRecordID * _Nullable ownerRecordID, NSError * _Nullable error) {
        CKRecordID *recordID = [[CKRecordID alloc] initWithRecordName:@"your_record_name_e.g._UUID" zoneID:ownerRecordID.zoneID]; 
        CKRecord *record = [[CKRecord alloc] initWithRecordType:@"your_record_type" recordID:recordID];
        record[@"your_video_asset_CK_key"] = assetVideo;
        record[@"your_image_asset_CK_key"] = assetImage;

        CKModifyRecordsOperation * op = [[CKModifyRecordsOperation alloc] initWithRecordsToSave:@[record] recordIDsToDelete:nil];
        op.modifyRecordsCompletionBlock = ^void(NSArray<CKRecord *> * _Nullable savedRecords, NSArray<CKRecordID *> * _Nullable deletedRecordIDs, NSError * _Nullable operationError){
            block(savedRecords.firstObject);    // Done.
        }; 

        op.qualityOfService = NSQualityOfServiceUserInitiated;

        [ckdbPublic addOperation:op];
    }];
}

第二部分(从 iCloud 检索)有一个小“技巧”​​——您应该确保图像和视频在元数据中具有相同的 Assets ID，否则 iOS 将不知道这两部分(视频和图像)属于到一个复合 Assets - 实时照片 - 并且无法将它们组合成单个正确 PHLivePhoto 对象(但是，在这种情况下，您很可能会 获取 PHLivePhoto，但它将被构造为静态照片，没有动画)。

这里最简单的方法是从视频 Assets 中提取 Assets ID，然后通过为其分配相同的 ID 来修改图像部分:

- (void) assembleLivePhotoWithCKRecord:(nonnull CKRecord*)record completion:(void (^__nullable)(PHLivePhoto* _Nullable livePhoto))block
{
    // Operational data
    CKAsset *assetVideo = record[@"your_video_asset_CK_key"];
    CKAsset *assetImage = record[@"your_image_asset_CK_key"];

    // Get video and prepare local URLs
    NSString *fileName = [[NSUUID UUID] UUIDString];
    NSString *pathVideo = [NSTemporaryDirectory() stringByAppendingPathComponent:[fileName stringByAppendingPathExtension:@"mov"]];
    NSString *pathImage = [NSTemporaryDirectory() stringByAppendingPathComponent:[fileName stringByAppendingPathExtension:@"jpg"]];
    NSURL *urlVideo = [NSURL fileURLWithPath:pathVideo];
    NSURL *urlImage = [NSURL fileURLWithPath:pathImage];

    NSData *dataVideo = [NSData dataWithContentsOfURL:assetVideo.fileURL];
    [[NSFileManager defaultManager] createFileAtPath:pathVideo contents:dataVideo attributes:nil];

    // Getting video asset ID from metadata
    NSString *metaID = nil;
    NSArray<AVMetadataItem*>* metadata = [[AVURLAsset assetWithURL:urlVideo] metadata];
    for (AVMetadataItem *md in metadata){
        if ([md.identifier containsString:@"com.apple.quicktime.content.identifier"]){
            metaID = (NSString*)(md.value);
            break;
        }
    }

    // Get image
    NSData *dataImage = [NSData dataWithContentsOfURL:assetImage.fileURL];
    UIImage *image = [UIImage imageWithData:dataImage];
    CGImageRef ref = [image CGImage];

    // Update image's metadata to make it conform video metadata
    NSDictionary *imgMetadata = @{@"{MakerApple}": @{@"17": metaID}};
    NSMutableData *imageData = [NSMutableData new];
    CGImageDestinationRef dest = CGImageDestinationCreateWithData((CFMutableDataRef)imageData, kUTTypeJPEG, 1, nil);
    CGImageDestinationAddImage(dest, ref, (CFDictionaryRef)imgMetadata);
    CGImageDestinationFinalize(dest);

    [imageData writeToFile:pathImage atomically:YES];


    [PHLivePhoto requestLivePhotoWithResourceFileURLs:@[urlImage, urlVideo] placeholderImage:nil targetSize:CGSizeZero contentMode:PHImageContentModeAspectFit resultHandler:^(PHLivePhoto * _Nullable livePhoto, NSDictionary * _Nonnull info) {
        block(livePhoto);       // NOTE: this block may be called several times
    }];
}

根据 Apple 的文档，可能会多次调用带有实时照片的结果 block (有关详细信息，请参阅 PHLivePhoto.h):

The result handler will be called multiple times to deliver new PHLivePhoto instances with increasingly more content.

此外，请记住，您应该添加所有必要的检查(实际上有很多)和错误处理程序等。