Get an example of the picture in the system album in iOS

This article introduces the acquisition of pictures in the system album in iOS. It can be used in many applications. You can obtain single pictures or multiple pictures at the same time. I won’t say much nonsense, let’s see below.

1. Get a single picture

Ideas:

1. UIImagePickerController can obtain pictures from the system's own App (Photo\Camera)

2. Set up a proxy and comply with the proxy agreement

Note that this UIImagePickerController class is quite special and requires compliance with two proxy protocols.

@interface ViewController () <UIImagePickerControllerDelegate, UINavigationControllerDelegate>

3. Methods to implement proxy didFinishPickingMediaWithInfo

- (void)getImageFromIpc
{
  // 1. Determine whether the album can be opened  if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) return;
  // 2. Create a picture selection controller  UIImagePickerController *ipc = [[UIImagePickerController alloc] init];
  /**
    typedef NS_ENUM(NSInteger, UIImagePickerControllerSourceType) {
    UIImagePickerControllerSourceTypePhotoLibrary, // Photo Album
    UIImagePickerControllerSourceTypeCamera, // Use the camera to obtain
    UIImagePickerControllerSourceTypeSavedPhotosAlbum // Photo Album
    }
    */
  // 3. Set the open photo album type (show all photo albums)   = UIImagePickerControllerSourceTypePhotoLibrary;
  //  = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
  // Camera  //  = UIImagePickerControllerSourceTypeCamera;
  // 4. Set up a proxy   = self;
  // Out of this controller  [self presentViewController:ipc animated:YES completion:nil];
}

#pragma mark -- &lt;UIImagePickerControllerDelegate&gt;--
// Operation after obtaining pictures- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary&lt;NSString *,id&gt; *)info
{
  // Destroy the controller  [picker dismissViewControllerAnimated:YES completion:nil];

  // Set pictures   = info[UIImagePickerControllerOriginalImage];
}

2. Get multiple pictures

Ideas:

Import header file #import <Photos/>
PHAsset: a resource, such as a picture\a video
PHAssetCollection: an album
PHImageManager Image Manager is a singleton, and only by sending a request can you get the picture from the asset
PHImageRequestOptions Image Request Options
Note: This class is the method before iOS8 started to promote and iOS9 started to be abandoned
Before the system is adapted to iOS8, use the API in the following library

#import <AssetsLibrary/>

1. Obtain the original image of all albums

- (void)getOriginalImages
{
  // Get all custom albums  PHFetchResult&lt;PHAssetCollection *&gt; *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
  // traverse all custom albums  for (PHAssetCollection *assetCollection in assetCollections) {
    [self enumerateAssetsInAssetCollection:assetCollection original:YES];
  }

  // Obtain the camera roll  PHAssetCollection *cameraRoll = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil].lastObject;
  //Travel over the camera roll and get large images  [self enumerateAssetsInAssetCollection:cameraRoll original:YES];
}

2. Obtain thumbnails in all albums

- (void)getThumbnailImages
{
  // Get all custom albums  PHFetchResult&lt;PHAssetCollection *&gt; *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
  // traverse all custom albums  for (PHAssetCollection *assetCollection in assetCollections) {
    [self enumerateAssetsInAssetCollection:assetCollection original:NO];
  }
  // Obtain the camera roll  PHAssetCollection *cameraRoll = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil].lastObject;
  [self enumerateAssetsInAssetCollection:cameraRoll original:NO];
}

3.Travel the album

/**
  * Traverse all pictures in the album
  * @param assetCollection Photo Album
  * @param original Do you want the original image?
  */
- (void)enumerateAssetsInAssetCollection:(PHAssetCollection *)assetCollection original:(BOOL)original
{
  NSLog(@"Album name:%@", );

  PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
  // Get the picture synchronously, only 1 picture will be returned   = YES;

  // Get all PHAsset objects in an album  PHFetchResult&lt;PHAsset *&gt; *assets = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];
  for (PHAsset *asset in assets) {
    // Do you want the original image    CGSize size = original ? CGSizeMake(, ) : CGSizeZero;

    // Get the picture from the asset    [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:size contentMode:PHImageContentModeDefault options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
      NSLog(@"%@", result);
    }];
  }
}

The above is all the content of this article. I hope it will be helpful to everyone's study and I hope everyone will support me more.