swift 代码实现方法调用

class X {
  @objc func sayHiTo(name: String) {
    print("Hello \(name)!")
  }
}

let obj = X()
let sel = #selector(obj.sayHiTo)
let method = class_getInstanceMethod(object_getClass(obj), sel)
let imp = method_getImplementation(method)

typealias ClosureType = @convention(c) (AnyObject, Selector, String) -> Void
let sayHiTo : ClosureType = unsafeBitCast(imp, ClosureType.self)
sayHiTo(obj, sel, "May")