iOS image saving and search function

This article implements the common functions of Photos.framework, including: creating custom albums, saving pictures to custom albums, and searching for pictures of all albums. The details are as follows
1. Save the picture to the album

/**
 *  Save the picture to the album 
 */
- (IBAction)saveImage {
  PHAuthorizationStatus status = [PHPhotoLibrary authorizationStatus];
  if (status == PHAuthorizationStatusDenied) {
    NSLog(@" Please go to Settings - privacy - Photo: turn on the access switch ");
  } else if (status == PHAuthorizationStatusRestricted) {
    NSLog(@" Unable to access album ");
  } else {
    //  Save photo identification 
    __block NSString *assetId = nil;
       
    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
      //  Save the photo to the camera film and return the logo 
      assetId = [PHAssetCreationRequest creationRequestForAssetFromImage:[UIImage imageNamed:@"logo"]].placeholderForCreatedAsset.localIdentifier;
    } completionHandler:^(BOOL success, NSError * _Nullable error) {
      if (!success) {
        NSLog(@" Save failed: %@", error);
        return;
      }
         
      //  Get a photo object according to the logo 
      PHAsset *asset = [PHAsset fetchAssetsWithLocalIdentifiers:@[assetId] options:nil].lastObject;
         
      //  Get the custom photo album object 
      PHAssetCollection *collection = [self collection];
      if (collection == nil) return;
         
      //  Save the photo to a custom album 
      [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
        [[PHAssetCollectionChangeRequest changeRequestForAssetCollection:collection] addAssets:@[asset]];
      } completionHandler:^(BOOL success, NSError * _Nullable error) {
        if (success) {
          NSLog(@" Save success ");
        } else {
          NSLog(@" Save failed: %@", error);
        }
      }];
    }];
  }
}

2. Search for all photos

/**
 *  Query all images 
 */
- (IBAction)searchAllImages {
     
  //  Walk through all the custom albums 
  PHFetchResult<PHAssetCollection *> *collectionResult0 = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
  for (PHAssetCollection *collection in collectionResult0) {
    [self searchAllImagesInCollection:collection];
  }
     
  //  Get a picture of the camera film 
  PHFetchResult<PHAssetCollection *> *collectionResult1 = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
  for (PHAssetCollection *collection in collectionResult1) {
    if (![collection.localizedTitle isEqualToString:@"Camera Roll"]) continue;
    [self searchAllImagesInCollection:collection];
    break;
  }
}
   
/**
 *  Look up all the pictures in an album 
 */
- (void)searchAllImagesInCollection:(PHAssetCollection *)collection
{
  //  Take sync to get the picture (only get it 1 A picture) 
  PHImageRequestOptions *imageOptions = [[PHImageRequestOptions alloc] init];
  imageOptions.synchronous = YES;
     
  NSLog(@" Photo album name: %@", collection.localizedTitle);
     
  //  Walk through all the pictures in the album 
  PHFetchResult<PHAsset *> *assetResult = [PHAsset fetchAssetsInAssetCollection:collection options:nil];
  for (PHAsset *asset in assetResult) {
    //  Filter non-image 
    if (asset.mediaType != PHAssetMediaTypeImage) continue;
       
    //  Size of picture 
    CGSize targetSize = CGSizeMake(asset.pixelWidth, asset.pixelHeight);
    //  Request the picture 
    [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:targetSize contentMode:PHImageContentModeDefault options:imageOptions resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
      NSLog(@" Image: %@", result);
    }];
  }
}

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