iOS开发--利用Photos.framework获取/操作本地

1. 隐私申请权限

2. 同步获取低质量的图片

// 申请资源类型
PHAssetCollection *cameraRoll =[PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil].lastObject;
    if (!cameraRoll) {
        block(nil);
        return;
    }
    PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
    //设置为异步还是同步，默认是异步
    options.synchronous = NO;
    options.deliveryMode = PHImageRequestOptionsDeliveryModeFastFormat;
    PHFetchResult *assets = [PHAsset fetchAssetsInAssetCollection:cameraRoll options:nil];
    //创建缓存管理器
    PHCachingImageManager *caching = [[PHCachingImageManager alloc] init];

    for (PHAsset *asset in assets) {
        if (asset.mediaType ==PHAssetMediaTypeImage) {
            //获取低质量图片
            [caching requestImageForAsset:asset targetSize:CGSizeMake(300, 300) contentMode:PHImageContentModeDefault options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
                if (result) {
                    NSLog(@"打印图片信息:%@", result);
                } 
            }];
        }
    }

为什么获取获取低质量图片?
低质量图片获取速度快,即使相册里有两百张照片,获取出来也是不到2s
如果是高清原图,两百张至少得30s,这样体验不好,并且同步会卡死主线程
为什么用同步?
异步获取会出现各种问题,有时获取不全

3. 获取高清图片

PHAsset *asset =nil;
if (!<#self.asset#>) {
    return;
}
asset =<#self.asset#>;

PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
options.resizeMode = PHImageRequestOptionsResizeModeNone;
//必须同步,否则有些照片获取不到.
options.synchronous = YES;
PHCachingImageManager *caching = [[PHCachingImageManager alloc] init];
//图片的原始尺寸
CGSize sizeOne = CGSizeMake(asset.pixelWidth, asset.pixelHeight);
    
[caching requestImageForAsset:asset targetSize:sizeOne contentMode:PHImageContentModeDefault options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
   if ([NSStringFromCGSize(result.size) isEqualToString:NSStringFromCGSize(sizeOne)]) {
      NSLog(@"高清照片信息:%@", result);
   }
}];

4. 删除某张照片

PHAsset *asset =nil;
if (!<#self.asset#>) {
   return;
}
asset =<#self.asset#>;

[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
   [PHAssetChangeRequest deleteAssets:@[asset]];
} completionHandler:^(BOOL success, NSError * _Nullable error) {
   dispatch_async(dispatch_get_main_queue(), ^{
       if (error) {
           NSLog(@"删除照片错误:%@", error);
       }
   });        
}];

5. 创建相册/保存照片到某相册

/// 创建相册(该相册存在则返回相册对象,不存在则创建并返回)
+ (PHAssetCollection *)creactNewPhotosGroupWinthName:(NSString *)name {
    NSString *title = name;
    // 获得所有的自定义相册
    PHFetchResult *collections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    for (PHAssetCollection *collection in collections) {
        if ([collection.localizedTitle isEqualToString:title]) {
            return collection;
        }
    }
    
    // 代码执行到这里，说明还没有自定义相册
    __block NSString *createdCollectionId = nil;
    // 创建一个新的相册
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
        createdCollectionId = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:title].placeholderForCreatedAssetCollection.localIdentifier;
    } error:nil];
    
    if (createdCollectionId == nil) return nil;
    
    // 创建完毕后再取出相册
    return [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[createdCollectionId] options:nil].firstObject;
}

/// 保存图片到指定相册
+ (void)saveImage:(UIImage *)image toCollection:(PHAssetCollection*)collection completionBlock:(void(^)(BOOL success, NSError * error))block {
    if (!image || ![image isKindOfClass:[UIImage class]]) {
        block(NO, [NSError errorWithDomain:@"图片格式不正确" code:0 userInfo:nil]);
        return;
    }
    __block NSString *assetId = nil;
    // 1. 存储图片到"相机胶卷"
    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
        PHAssetChangeRequest *request =[PHAssetCreationRequest creationRequestForAssetFromImage:image];
        // 2. 先保存图片到"相机胶卷",拿到标识符
        assetId = request.placeholderForCreatedAsset.localIdentifier;
//        request.location =[[CLLocation alloc]initWithLatitude:30.000 longitude:14.000];
    } completionHandler:^(BOOL success, NSError * _Nullable error) {
        if (error) {
            NSLog(@"保存到默认相册失败:%@", error);
            block(success, error);
            return;
        }
        //如果没指定相册对象,就不再处理
        if (!collection) {
            block(success, error);
            return;
        }
        // 3. 将“相机胶卷”中的图片添加到新的相册
        [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
            PHAssetCollectionChangeRequest *request = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:collection];
            // 根据唯一标示获得相片对象
            PHAsset *asset = [PHAsset fetchAssetsWithLocalIdentifiers:@[assetId] options:nil].firstObject;
            if (asset) {
                // 添加图片到相册中
                [request addAssets:@[asset]];
            }
        } completionHandler:^(BOOL success, NSError * _Nullable error) {
            block(success, error);
            if (error) {
                NSLog(@"保存到指定相册失败:%@", error);
            }
        }];
    }];
}

封装的代码地址:这是代码地址