UIButton上可以添加多个点击事件

同一个UIButton对象可添加多个action

btn.addTarget(self, action: #selector(firstClicktBtn(btn:)), for: .touchUpInside)
btn.addTarget(self, action: #selector(secondClicktBtn(btn:)), for: .touchUpInside)

@objc private func firstClicktBtn(btn: UIButton) {
        print("😂")
    }
@objc private func secondClicktBtn(btn: UIButton) {
        print("😄")
    }

当点击上面代码中的btn时，😂、😄会分别先后被打印。

UIButton对象移除某个action

btn.removeTarget(self, action: #selector(firstClicktBtn(btn:)), for: .touchUpInside)

btn.addTarget(self, action: #selector(firstClicktBtn(btn:)), for: .touchUpInside)
btn.removeTarget(self, action: #selector(firstClicktBtn(btn:)), for: .touchUpInside)
btn.addTarget(self, action: #selector(secondClicktBtn(btn:)), for: .touchUpInside)

将btn上的firstClicktBtn action移除后，再点击btn，就只打印😄了。