Argument of '#selector' refers to instance method 'action' that is not exposed to Objective-C

在 Swift 4.0 中会报错：Argument of '#selector' refers to instance method 'action' that is not exposed to Objective-C。解决办法有两种：
1、在该类前加上：

@objcMembers
class ViewController: UIViewController {
}

2、在方法名前加上：

@objc func action() {
        print("add")
}

作者：Desmond_
链接：https://www.jianshu.com/p/65a48d470139
来源：简书