Implement deletion of asset-library files

Summary:
WIP: Starting point insofar as I'm not sure if there should be an Android equivalent.

My application needs me to delete photos from the photos in iOS.

I have tested this in my application and it works, have a screenshot from iOS asking as well and it does successfully delete the photos from the global Photos app.

Related to facebook/react-native#15253, it kind of continues using the deprecated assets-library framework, but that does need (and will be an bigger and bigger issue coming up) of assets-library URLs being used.

I also assume RN prefers error handling at the JS level? Are the URLs starting with `asset-library`, etc.
Closes facebook/react-native#15481

Differential Revision: D6438016

Pulled By: hramos

fbshipit-source-id: 47512140f62f458c14ad2ade2b358846e168c964

CameraRoll.js

@@ -133,6 +133,10 @@ class CameraRoll {
     return this.saveToCameraRoll(tag, 'photo');
   }
 
+  static deletePhotos(photos: Array<string>) {
+    return RCTCameraRollManager.deletePhotos(photos);
+  }
+
   /**
    * Saves the photo or video to the camera roll / gallery.
    *

RCTCameraRollManager.m

@@ -12,6 +12,7 @@
 #import <CoreLocation/CoreLocation.h>
 #import <Foundation/Foundation.h>
 #import <UIKit/UIKit.h>
+#import <Photos/Photos.h>
 
 #import <React/RCTBridge.h>
 #import <React/RCTConvert.h>
@@ -234,6 +235,27 @@ static void RCTResolvePromise(RCTPromiseResolveBlock resolve,
   }];
 }
 
+RCT_EXPORT_METHOD(deletePhotos:(NSArray<NSString *>*)assets
+                  resolve:(RCTPromiseResolveBlock)resolve
+                  reject:(RCTPromiseRejectBlock)reject)
+{
+  NSArray<NSURL *> *assets_ = [RCTConvert NSURLArray:assets];
+  [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
+      PHFetchResult<PHAsset *> *fetched =
+        [PHAsset fetchAssetsWithALAssetURLs:assets_ options:nil];
+      [PHAssetChangeRequest deleteAssets:fetched];
+    }
+  completionHandler:^(BOOL success, NSError *error) {
+      if (success == YES) {
+     	    resolve(@(success));
+      }
+      else {
+	        reject(@"Couldn't delete", @"Couldn't delete assets", error);
+      }
+    }
+    ];
+}
+
 static void checkPhotoLibraryConfig()
 {
 #if RCT_DEV