I have a great experience on iOS programming: I'm the developer of FullControl, Cents and others.
I can't code for Android.
If you need to see my works please go to the AppStore and search for FullControl ( free download ). I am the developer behind Cents also ( if you download it, go to the info and you will see my name).
An other work is Color Maker, for Mac OS, available for free from the Mac App Store.
I prefer Object-C over Swift, but I will use the language of your choice, both are native.