init swizzling for swift.

init_swizzle.swift

public class Model: NSObject {
    @objc dynamic init(x: Int) {
        print("x: \(x)")
    }
    
    @objc dynamic init(y: Int) {
        print("y: \(y)")
    }
}


func swizzle() {
  let fromSelector = #selector(Model.init(x:))
    let toSelector = #selector(Model.init(y:))
    let from = class_getInstanceMethod(Model.self, fromSelector)!
    let to = class_getInstanceMethod(Model.self, toSelector)!
    method_exchangeImplementations(from, to)
}

  swizzle()
_ = Model.init(x: 1) // y: 1