How to call methods using selectors

func getClass(_ classNameString: String) -> AnyClass {

  let clazz = objc_getMetaClass(classNameString)

  return clazz as! AnyClass

}

func callMethod2(clazz: AnyClass, method: String) -> AnyObject {

  let selector : Selector = NSSelectorFromString(method)

  let method = class_getInstanceMethod((clazz), selector)!

  let methodIMP : IMP! = method_getImplementation(method)

  let newAmountObj = unsafeBitCast(methodIMP,to:(@convention(c)(AnyClass?,Selector,Any?)->Any).self)(clazz,selector, nil) as AnyObject

  return newAmountObj

}

func callMethod(clazz: AnyClass, method: String) -> AnyObject? {

  let selector : Selector = NSSelectorFromString(method)

  guard let method = class_getClassMethod((clazz), selector) else { return nil }

  let methodIMP : IMP! = method_getImplementation(method)

  let newAmountObj = unsafeBitCast(methodIMP,to:(@convention(c)(AnyClass?,Selector,Any?)->Any).self)(clazz,selector, nil) as AnyObject

  return newAmountObj

}

func callMethod(classNameString: String, method: String) -> AnyObject? {

  let clazz: AnyClass = getClass(classNameString)

  let newAmountObj = callMethod(clazz: clazz, method: method)

  return newAmountObj

}