报告来自子ViewController的更改

Question

如果一个ViewController继承自另一个ViewController，那么当父ViewController中的变量发生变化时，如何更新子ViewController中的东西？

class ViewControllerOne: UIViewController {

    var timer = Timer()

    var number: Int = 0  

    func updateNumber() {
        number += 1
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateNumber), userInfo: nil, repeats: true)
    }
}



class ViewControllerTwo: ViewControllerOne {
    // So in this class I want to print to the console when number is 3.
    // How do I check for that from this class?
}

Answer 1

覆盖updateNumber中的ViewControllerTwo。

override func updateNumber() {
    super.updateNumber()

    if number == 3 {
        // do something
    }
}