it puts warning that can't find custom ObjC classes. It is wrong for case if these classes are native. Bright examples -- classes from third party frameworks. In this case classes are present and this will not cause any runtime error.

[INFO] Cleaning output dir /
[WARNING] Failed to find Java classes for the following Objective-C classes in Storyboard/XIB files: [UIResponder, PieChartView]
[INFO] Compiling classes using 4 threads