Swizzling in Swift 3

Swizzling.swift

import Foundation

// Swizzling
extension NSObject {
    
    class func swizzleMethods(origSelector: Selector, withSelector: Selector, forClass: AnyClass) {
        let originalMethod = class_getInstanceMethod(forClass, origSelector)
        let swizzledMethod = class_getInstanceMethod(forClass, withSelector)
        method_exchangeImplementations(originalMethod, swizzledMethod)
    }
    
    func swizzleMethods(origSelector: Selector, withSelector: Selector) {
        let aClass: AnyClass! = object_getClass(self)
        NSObject.swizzleMethods(origSelector: origSelector, withSelector: withSelector, forClass: aClass)
    }
}

UIColor+Swizzling.swift

import UIKit

// Use Swizzling
public extension UIColor {
    
    func colorDescription() -> String {
        return "Some Custom text Here"
    }
    
    public class func swizzleDesription() {
        let instance = UIColor.red
        instance.swizzleMethods(origSelector: #selector(UIColor.colorDescription), withSelector: #selector(getter: NSObjectProtocol.description))
    }
}

// Somewhere in the Project
UIColor.swizzleDesription()
print(UIColor.red)