iOS 图片存进自定义的相册里去(只支持iOS8或以上的系统)

首先要判断有没有存进相册的权限，如果有就可以直接存，如果没有提醒用户开启访问相册的权限。
直接开代码：

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self saveMyFavoriteImageToCustomAlbum];
}

//开始存储我的图片到自定义的相册
- (void)saveMyFavoriteImageToCustomAlbum
{
    //判断有没有访问相册的权限
    PHAuthorizationStatus oldStatus = [PHPhotoLibrary authorizationStatus];
    if (oldStatus != PHAuthorizationStatusAuthorized)
    {
        //申请访问相册的权限
        [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
            dispatch_async(dispatch_get_main_queue(), ^{
                if (status != PHAuthorizationStatusAuthorized)
                {
                    NSLog(@"没有权限");
                }
                else
                {
                    NSLog(@"有权限");
                    UIImage *image = [UIImage imageNamed:@"传入想要存储的图片"];
                    [self savedPhotoToAlbumWithImage:image album:@"相册的名字"];
                }
            });
        }];
    }
    else
    {
        NSLog(@"有权限");
        UIImage *image = [UIImage imageNamed:@"传入想要存储的图片"];
        [self savedPhotoToAlbumWithImage:image album:@"相册的名字"];
    }
}

#pragma mark - 适配iOS8以上存储图片
//把图片存入指定的相册
- (void)savedPhotoToAlbumWithImage:(UIImage *)image album:(NSString *)photoAlbum
{
    //判断图片是不是为空
    if (image == nil || [PHPhotoLibrary authorizationStatus] != PHAuthorizationStatusAuthorized)
    {
        return;
    }
    //存储图片
    PHFetchResult<PHAsset *> *createdAssets = [self loadPhotoAssetsWithImage:image];
    if (createdAssets == nil)
    {
        //保存图片失败！
        return;
    }
    //创建相册
    PHAssetCollection *createdCollection = [self loadAlbumWithName:photoAlbum];
    if (createdCollection == nil)
    {
        //创建或者获取相册失败！
        return;
    }
    
    NSError *error = nil;
    //执行存储图片和创建相册
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
        PHAssetCollectionChangeRequest *request = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:createdCollection];
        [request insertAssets:createdAssets atIndexes:[NSIndexSet indexSetWithIndex:0]];
    } error:&error];
}

//创建一个相册
- (PHAssetCollection *)loadAlbumWithName:(NSString *)albumName
{
    NSString *albumNameTitle = (albumName.length != 0)? albumName : @"";
    //抓取所有的自定义相册（保证相册只被创建一个）
    PHFetchResult<PHAssetCollection *> *collections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    PHAssetCollection *createdCollection = nil;
    for (PHAssetCollection *collection in collections)
    {
        if ([collection.localizedTitle isEqualToString:albumNameTitle])
        {
            createdCollection = collection;
            break;
        }
    }
    //当前APP对应的自定义相册没有被创建过
    NSError *error = nil;
    if (createdCollection == nil)
    {
        __block NSString *createdCollectionID;
        [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
            //创建一个相册,拿到相册的唯一标识符
            createdCollectionID = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:albumNameTitle].placeholderForCreatedAssetCollection.localIdentifier;
        } error:&error];
        
        //根据相册的唯一标识符拿到相册
        createdCollection = [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[createdCollectionID] options:nil].firstObject;
    }
    return createdCollection;
}

//保存图片
- (PHFetchResult<PHAsset *> *)loadPhotoAssetsWithImage:(UIImage *)saveImage
{
    NSError *error = nil;
    __block NSString *assetID = nil;
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{//同步
        assetID = [PHAssetChangeRequest creationRequestForAssetFromImage:saveImage].placeholderForCreatedAsset.localIdentifier;
    } error:&error];
    if (error)
    {
        return nil;
    }
    return [PHAsset fetchAssetsWithLocalIdentifiers:@[assetID] options:nil];
}