iOS 保存图片（视频）到相册

一、C语言函数方式实现

注意：UIImageWriteToSavedPhotosAlbum方法必须实现代理方法，不然会崩溃。

//参数1:图片对象
//参数2:成功方法绑定的target
//参数3:成功后调用方法
//参数4:须要传递信息(成功后调用方法的参数)
UIImageWriteToSavedPhotosAlbum(self.imageView.image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
#pragma mark -- <保存到相册>
-(void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {
    NSString *msg = nil ;
    if(error){
        msg = @"保存图片失败" ;
    }else{
        msg = @"保存图片成功" ;
    }
}

方法2：使用Photos框架实现

2.1 Photos01-基本认识

PHAsset : 一个PHAsset对象就表明相册中的一张图片或者一个视频
PHAssetCollection : 一个PHAssetCollection 对象就表明一个相册

若是咱们想保存图片到【相机胶卷】，首先要保证添加一个新的PHAsset对象，那么如何操做这些对象呢？无非是对这些对象进行增删改查。

PHAsset 一个PHAsset对象就表明相册中的一张图片或者一个视频
增删改 PHAssetChangeRequest 包括图片/视频相关的改动操做

查 [PHAsset fetchAssets...];

PHAssetCollection 一个PHAssetCollection 对象就表明一个相册

增删改 PHAssetCollectionChangeRequest 包括相册相关的全部改动操做

查 [PHAssetCollection fetchAssetCollectionsContainingAsset:...];

2.2 Photos02-保存图片到相机胶卷

//保存图片到【相机胶卷】
    /// 异步执行修改操做
    [[PHPhotoLibrary sharedPhotoLibrary]performChanges:^{
        [PHAssetChangeRequest creationRequestForAssetFromImage:self.imageView.image];
    } completionHandler:^(BOOL success, NSError * _Nullable error) {
        if (error) {
            NSLog(@"%@",@"保存失败");
        } else {
            NSLog(@"%@",@"保存成功");
        }
    }];

2.3 Photos03-建立新的相册

NSError *error = nil;
    [[PHPhotoLibrary sharedPhotoLibrary]performChangesAndWait:^{
        //获取app名字
        
        NSString *title = [NSBundle mainBundle].infoDictionary[(__bridge NSString*)kCFBundleNameKey];
        //建立一个【自定义相册】
        [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:title];
    } error:&error];

2.4 Photos04-查询相册

NSString *title = [NSBundle mainBundle].infoDictionary[(__bridge NSString*)kCFBundleNameKey];
    //查询全部【自定义相册】
    PHFetchResult<PHAssetCollection *> *collections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    PHAssetCollection *createCollection = nil;
    for (PHAssetCollection *collection in collections) {
        if ([collection.localizedTitle isEqualToString:title]) {
            createCollection = collection;
            break;
        }
    }
if (createCollection == nil) {
        //当前对应的app相册没有被建立
        //建立一个【自定义相册】
        NSError *error = nil;
        __block NSString *createCollectionID = nil;
        [[PHPhotoLibrary sharedPhotoLibrary]performChangesAndWait:^{
            //建立一个【自定义相册】
           createCollectionID = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:title].placeholderForCreatedAssetCollection.localIdentifier;
        } error:&error];
        createCollection = [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[createCollectionID] options:nil].firstObject;
    }
    NSLog(@"%@",createCollection);

2.5 Photos05-保存图片到自定义相册

// 1.先保存图片到【相机胶卷】
    /// 同步执行修改操做
    NSError *error = nil;
    __block PHObjectPlaceholder *placeholder = nil;
    [[PHPhotoLibrary sharedPhotoLibrary]performChangesAndWait:^{
       placeholder =  [PHAssetChangeRequest creationRequestForAssetFromImage:self.imageView.image].placeholderForCreatedAsset;
    } error:&error];
    if (error) {
        NSLog(@"保存失败");
        return;
    }
    // 2.拥有一个【自定义相册】
    PHAssetCollection * assetCollection = self.createCollection;
    if (assetCollection == nil) {
        NSLog(@"建立相册失败");
    }
    // 3.将刚才保存到【相机胶卷】里面的图片引用到【自定义相册】
    [[PHPhotoLibrary sharedPhotoLibrary]performChangesAndWait:^{
        PHAssetCollectionChangeRequest *requtes = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:assetCollection];
        [requtes addAssets:@[placeholder]];
    } error:&error];
    if (error) {
        NSLog(@"保存图片失败");
    } else {
        NSLog(@"保存图片成功");
    }