How can i use Bitcoin payment method through Swift for my IOS Project?
Core Bitcoin is a library for iOS written in Objective-C.  I have worked with it in Swift using the bridging header.  

I myself have written a few Swift classes, in my experimental/educational wallet, for creating addresses, keys, and transactions, but I wouldn't recommend using it for anything.  Feel free to take a look and see if you find anything interesting, or anything that you could learn from.