Snapshot to use key window size if possible

Summary:
Use the application key window bounds if possible.
In the case where the application is not using the entire screen,
like in Split View on an iPad, the running application is
not using the entire screen thus the snapshot stretches to
fill the screen size which is incorrect.

Reviewed By: LukeDefeo

Differential Revision: D47793033

fbshipit-source-id: d6c7932d35bad13752713772d078f94bad530b09

iOS/Plugins/FlipperKitUIDebuggerPlugin/FlipperKitUIDebuggerPlugin/Utilities/UIDSnapshot.m

@@ -25,6 +25,16 @@
 
 UIImage* UIDApplicationSnapshot(UIApplication* application, NSArray* windows) {
   CGSize size = [UIScreen mainScreen].bounds.size;
+
+  // Use the application key window bounds if possible.
+  // In the case where the application is not using the entire screen,
+  // like in Split View on an iPad, the running application is
+  // not using the entire screen thus the snapshot stretches to
+  // fill the screen size which is incorrect.
+  if (application.keyWindow) {
+    size = application.keyWindow.bounds.size;
+  }
+
   UIGraphicsImageRenderer* renderer =
       [[UIGraphicsImageRenderer alloc] initWithSize:size];