Xamarin.Forms are awesome for building applications, but eventually you have to get dirty and fix platform specific issues. And once down there, one quickly realizes that native development is not so much different than native development for that platform itself.
Let’s take a look at the relatively simple problem with iOS: changing the unselected color for the tab bar icons. Searching the web brings us to the den of programming solutions, Stack Overflow, with the following solution http://stackoverflow.com/questions/11512783/unselected-uitabbar-color. The code is straightforward:
UIColor * unselectedColor = [UIColor colorWithRed:184/255.0f green:224/255.0f blue:242/255.0f alpha:1.0f]; item.image = [[item.selectedImage imageWithColor:unselectedColor] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];