use Photos framework to export xmp data into the iOS Photo Gallery

engine/canvas.cpp

@@ -4,6 +4,7 @@
 
 #ifdef __APPLE__
 #include <Foundation/Foundation.h>
+#import <Photos/Photos.h>
 #endif
 
 
@@ -837,8 +838,18 @@ void ui::Canvas::export_equirectangular(std::string data_path)
         inject_xmp(name);
         //int ret = stbi_write_png(name, m_latlong.getWidth(), m_latlong.getHeight(), 4, latlong_data.get(), m_latlong.stride());
 #ifdef __IOS__
-        image = [UIImage imageWithContentsOfFile:[NSString stringWithUTF8String:name]];
-        UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
+        [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
+            NSURL* url = [NSURL fileURLWithPath:[NSString stringWithUTF8String:name]];
+            PHAssetChangeRequest *changeRequest = [PHAssetChangeRequest creationRequestForAssetFromImageAtFileURL:url];
+            changeRequest.creationDate          = [NSDate date];
+        } completionHandler:^(BOOL success, NSError *error) {
+            if (success) {
+                NSLog(@"successfully saved");
+            }
+            else {
+                NSLog(@"error saving to photos: %@", error);
+            }
+        }];
 #endif
     }