相簿

先看看相簿的结构

接下来我们看看相册的函数

  // Adds a photo to the saved photos album.  The optional completionSelector should have the form:
  //  - (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo;
void UIImageWriteToSavedPhotosAlbum(UIImage *image, __nullable id completionTarget, __nullable SEL completionSelector, void * __nullable contextInfo) 

#ForExample:
  

UIImageWriteToSavedPhotosAlbum(self.imageView.image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
## 上面的函数执行完会调用下面的方法因为@selector的原因
/**
 *  通过UIImageWriteToSavedPhotosAlbum函数写入图片完毕后就会调用这个方法
 *
 *  @param image       写入的图片
 *  @param error       错误信息
 *  @param contextInfo UIImageWriteToSavedPhotosAlbum函数的最后一个参数
 */
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    if (error) {
        [SVProgressHUD showErrorWithStatus:@"图片保存失败!"];
    } else {
        [SVProgressHUD showSuccessWithStatus:@"图片保存成功!"];
    }
}

再来看看用框架的类和方法

#import 
#import   
#import  

PHAsset -------  // 一张图片,一个资源,一段视频
PHCollection ---   //  一本相簿

assetCollectionLocalIdentifier   // PHAssetCollection的标识, 利用这个标识可以找到对应的PHAssetCollection对象(相簿对象)
assetLocalIdentifier    // PHAsset的标识, 利用这个标识可以找到对应的PHAsset对象(图片对象)
 
 // 如果想对"相册"进行修改(增删改), 那么修改代码必须放在
[PHPhotoLibrary sharedPhotoLibrary]的performChanges方法的block中

保存图片到相机中的具体步骤

// 0 . 判断授权状态

    PHAuthorizationStatus status = [PHPhotoLibrary authorizationStatus];
   /*
 PHAuthorizationStatusNotDetermined,     用户还没有做出选择
 PHAuthorizationStatusDenied,            用户拒绝当前应用访问相册(用户当初点击了"不允许")
 PHAuthorizationStatusAuthorized         用户允许当前应用访问相册(用户当初点击了"好")
 PHAuthorizationStatusRestricted,        因为家长控制, 导致应用无法方法相册(跟用户的选择没有关系)
   */

// 1 .保存图片到"相机胶卷中"
// 2. 创建相簿
// 3. 添加相机胶卷中的图片到新建的相簿中

 // 如果想对"相册"进行修改(增删改), 那么修改代码必须放在[PHPhotoLibrary sharedPhotoLibrary]的performChanges方法的block中
    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
 // 1.保存图片A到"相机胶卷"中
        // 创建图片的请求
        assetLocalIdentifier = [PHAssetCreationRequest creationRequestForAssetFromImage:self.imageView.image].placeholderForCreatedAsset.localIdentifier;
    } completionHandler:^(BOOL success, NSError * _Nullable error) {
        if (success == NO) {
            XMGLog(@"保存[图片]到[相机胶卷]中失败!失败信息-%@", error);
            return;
        }
// 获得曾经创建过的相簿
        PHAssetCollection *createdAssetCollection = [self createdAssetCollection];
        if (createdAssetCollection) { // 曾经创建过相簿
            [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
                // 3.添加"相机胶卷"中的图片A到"相簿"D中
                
                // 获得图片
                PHAsset *asset = [PHAsset fetchAssetsWithLocalIdentifiers:@[assetLocalIdentifier] options:nil].lastObject;
                
                // 添加图片到相簿中的请求
                PHAssetCollectionChangeRequest *request = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:createdAssetCollection];
                
                // 添加图片到相簿
                [request addAssets:@[asset]];
            } completionHandler:^(BOOL success, NSError * _Nullable error) {
                if (success == NO) {
                    XMGLog(@"添加[图片]到[相簿]失败!失败信息-%@", error);
                } else {
                    XMGLog(@"成功添加[图片]到[相簿]!");
                }
            }];
        } 
      else { // 没有创建过相簿
            [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
                // 2.创建"相簿"D
                // 创建相簿的请求
                assetCollectionLocalIdentifier = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:XMGAssetCollectionTitle].placeholderForCreatedAssetCollection.localIdentifier;
            } completionHandler:^(BOOL success, NSError * _Nullable error) {
                if (success == NO) {
                    XMGLog(@"保存相簿失败!失败信息-%@", error);
                    return;
                }
                
                [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
                    // 3.添加"相机胶卷"中的图片A到新建的"相簿"D中
                    
                    // 获得相簿
                    PHAssetCollection *assetCollection = [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[assetCollectionLocalIdentifier] options:nil].lastObject;
                    
                    // 获得图片
                    PHAsset *asset = [PHAsset fetchAssetsWithLocalIdentifiers:@[assetLocalIdentifier] options:nil].lastObject;
                    
                    // 添加图片到相簿中的请求
                    PHAssetCollectionChangeRequest *request = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:assetCollection];
                    
                    // 添加图片到相簿
                    [request addAssets:@[asset]];
                } completionHandler:^(BOOL success, NSError * _Nullable error) {
                    if (success == NO) {
                        XMGLog(@"添加[图片]到[相簿]失败!失败信息-%@", error);
                    } else {
                        XMGLog(@"成功添加[图片]到[相簿]!");
                    }
                }];
            }];
        }
    }];

/**
 *  获得曾经创建过的相簿
 */
- (PHAssetCollection *)createdAssetCollection
{
    PHFetchResult *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    
    for (PHAssetCollection *assetCollection in assetCollections) {
        if ([assetCollection.localizedTitle isEqualToString:XMGAssetCollectionTitle]) {
            return assetCollection;
        }
    }
    
    return nil;
}