PhotoKit架構介紹及使用，photokit架構介紹

PhotoKit架構介紹及使用，photokit架構介紹

　　PhotoKit 是一套比 AssetsLibrary 更新更完整也更高效的ios照片處理庫，對資源的處理跟 AssetsLibrary 有很大的不同。下面簡單介紹下PhotoKit的幾個基本概念

• PHAsset：代表照片庫中的特定資源，PHAsset對象來表示儲存在照片應用程式中或雲端的一個圖片或視頻檔案。為了顯示或編輯asset，我們需要使用PHAsset類的擷取asset來處理它，一個asset對象是不可變的，只包含它所代表的照片或視頻的中繼資料。
• PHFetchOptions：使用PHFetchOptions對象來指定選項，在PHAsset, PHCollection, PHAssetCollection, and PHCollectionList上根據它的對象來檢索照片符合要求的實體。我們可以根據一些key來對要顯示的照片進行排序。下面是支援的key
• PHFetchResult: 表示一系列的資源集合，也可以是相簿的集合。它是一個有序的儲存照片實體的容器。它是一個泛型集合
• PHAssetCollection: 表示一個相簿
• PHImageManager: 用於處理資源的載入，載入圖片的過程帶有緩衝處理，可以通過傳入一個 PHImageRequestOptions 控制資源的輸出尺寸等規格
• PHImageRequestOptions: 控制載入圖片時的一系列參數

下面詳細介紹庫的使用

我們需要匯入Photos.framework

1.PHPhotoLibrary：表示使用者的照片庫，包括Object Storage Service在本地裝置和（如果已啟用）在iCloud照片。我們使用PHPhotoLibrary來對照片庫進行操作。可以添加編輯刪除。

例如使用PHPhotoLibrary來實現拍照功能。

    [_mCamera capturePhotoAsJPEGProcessedUpToFilter:_mFilter withCompletionHandler:^(NSData *processedJPEG, NSError *error){        [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{        [[PHAssetCreationRequest creationRequestForAsset] addResourceWithType:PHAssetResourceTypePhoto data:processedJPEG options:nil];        } completionHandler:^(BOOL success, NSError * _Nullable error) {                    }];    }];

 

 

2.PHAssetChangeRequest，PHAssetCollectionChangeRequest，PHAssetCreationRequest，PHCollectionListChangeRequest：你可以在PHPhotoLibrary的change block中建立一個它們的對象來對asset對象進行添加，編輯，刪除

在上面那段代碼中我們展現了PHAssetCreationRequest的添加操作。

[[PHAssetCreationRequest creationRequestForAsset] addResourceWithType:PHAssetResourceTypePhoto data:processedJPEG options:nil];

 

 

3.PHAssetCollectionType相簿類型

typedef NS_ENUM(NSInteger, PHAssetCollectionType) {    PHAssetCollectionTypeAlbum      = 1,    PHAssetCollectionTypeSmartAlbum = 2,    PHAssetCollectionTypeMoment     = 3,} NS_ENUM_AVAILABLE_IOS(8_0);

 

[PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil]

輸出：

2016-09-29 15:27:59.392 FWLifeApp[1040:36950] Favorites2016-09-29 15:27:59.394 FWLifeApp[1040:36950] Recently Deleted2016-09-29 15:27:59.394 FWLifeApp[1040:36950] Panoramas2016-09-29 15:27:59.394 FWLifeApp[1040:36950] Camera Roll2016-09-29 15:27:59.396 FWLifeApp[1040:36950] Slo-mo2016-09-29 15:27:59.396 FWLifeApp[1040:36950] Screenshots2016-09-29 15:27:59.397 FWLifeApp[1040:36950] Bursts2016-09-29 15:27:59.398 FWLifeApp[1040:36950] Videos2016-09-29 15:27:59.398 FWLifeApp[1040:36950] Selfies2016-09-29 15:27:59.399 FWLifeApp[1040:36950] Hidden2016-09-29 15:27:59.400 FWLifeApp[1040:36950] Time-lapse2016-09-29 15:27:59.400 FWLifeApp[1040:36950] Recently Added

 

我們可以看出PHAssetCollectionTypeSmartAlbum包含許多相簿集。收藏，最近刪除，最近添加，相機菲林等，而不包含時刻.

NSMutableArray<FWPhotoAlbums *> *mArr = [NSMutableArray array];    PHFetchResult *smartAlbum = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];    [smartAlbum enumerateObjectsUsingBlock:^(PHAssetCollection *  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
//過濾掉最近刪除的，和視頻        if (obj.assetCollectionSubtype != 202 && obj.assetCollectionSubtype < 212) {            NSArray <PHAsset *> *assets = [self getAssetsInAssetCollection:obj ascending:NO];            if ([assets count]) {                FWPhotoAlbums *pa = [[FWPhotoAlbums alloc] init];                pa.albumName = [self TitleOfAlbumForChinse:obj.localizedTitle];                pa.albumImageCount = [assets count];                pa.firstImageAsset = assets.firstObject;                pa.assetCollection = obj;                [mArr addObject:pa];            }        }    }];

 

我們需要進一步擷取每個相簿集下的所有照片。對照片的creationDate key進行排序

- (PHFetchResult *)fetchAssetsInAssetCollection:(PHAssetCollection *)assetCollection ascending:(BOOL)ascending{    PHFetchOptions *options = [[PHFetchOptions alloc] init];    options.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:ascending]];    PHFetchResult *result = [PHAsset fetchAssetsInAssetCollection:assetCollection options:options];        return result;}- (NSArray <PHAsset *> *)getAssetsInAssetCollection:(PHAssetCollection *)assetCollection ascending:(BOOL)ascending{    NSMutableArray <PHAsset *> *mArr = [NSMutableArray array];    PHFetchResult *result = [self fetchAssetsInAssetCollection:assetCollection ascending:ascending];    [result enumerateObjectsUsingBlock:^(PHAsset *  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {        if (obj.mediaType == PHAssetMediaTypeImage) {            [mArr addObject:obj];        }    }];        return mArr;}

 

擷取圖片

- (void)requestImageForAsset:(PHAsset *)asset size:(CGSize)size resizeMode:(PHImageRequestOptionsResizeMode)resizeMode completion:(void (^)(UIImage *, NSDictionary *))completion{    static PHImageRequestID requestID = -1;    CGFloat scale = [UIScreen mainScreen].scale;    CGFloat width = MIN(WIDTH, 800);    if (requestID >= 1 && size.width/width==scale) {        [[PHCachingImageManager defaultManager] cancelImageRequest:requestID];    }        PHImageRequestOptions *option = [[PHImageRequestOptions alloc] init];    option.resizeMode = resizeMode;    option.networkAccessAllowed = YES;        requestID = [[PHCachingImageManager defaultManager] requestImageForAsset:asset targetSize:size contentMode:PHImageContentModeAspectFill options:option resultHandler:^(UIImage * _Nullable image, NSDictionary * _Nullable info) {        BOOL downloadFinined = ![[info objectForKey:PHImageCancelledKey] boolValue] && ![info objectForKey:PHImageErrorKey];        if (downloadFinined && completion) {            completion(image, info);        }    }];}