Swift instance method swizzling

MethodSwizzling.swift

import Foundation

class FavoriteCity {
    dynamic func currentWinner() -> String {
        return "Vancouver"
    }
    
    dynamic func lastWinner() -> String {
        return "Shanghai"
    }
}

let myFavoriteCity = FavoriteCity()
print(myFavoriteCity.currentWinner())

// Let's swizzle
let aClass = FavoriteCity.self
let originalMethod = class_getInstanceMethod(aClass, "currentWinner")
let swizzledMethod = class_getInstanceMethod(aClass, "lastWinner")
method_exchangeImplementations(originalMethod, swizzledMethod)

print(myFavoriteCity.currentWinner())
print(myFavoriteCity.lastWinner())