How to color a UIButton in a specific ratio?

Question

Objective-C

The iOS platform, xcode development environment is considered.
There is a button (let's say green). How to programmatically paint it in a different color in some ratio from left to right or top to bottom? An example in the picture.

Answer 1

There are various options, starting with a vector / raster image and ending with drawInRect
Here is an excellent overview article where we went through everything (except for the CALayer mentioned above)
https://robots.thoughtbot.com/designing-for-ios-ta...
Here's more from Ray only with CoreGraphics www.raywenderlich.com/33330/core-graphics-tutorial...
How to draw two squares, I think you google it yourself
PS Personally, I prefer the option with DRawRect