Question

navigationController?.setViewControllers在override func viewDidAppear(中延迟工作，在其他情况下，它可以正常工作。

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    print(self.navigationController?.children)
    print(self.navigationController?.viewControllers)
    var array = self.navigationController?.children
    array!.insert(ViewController(), at: array!.count - 1)
    navigationController?.setViewControllers(array!, animated: false)
    print(self.navigationController?.viewControllers)
}

它打印：

Optional([<One.ViewController: 0x7f9a1b4021e0>, <One.TwoViewController: 0x7f9a1b40e320>])
Optional([<One.ViewController: 0x7f9a1b4021e0>, <One.TwoViewController: 0x7f9a1b40e320>])
Optional([<One.ViewController: 0x7f9a1b4021e0>, <One.TwoViewController: 0x7f9a1b40e320>])

在其他情况下，它可以正常工作。就像单击按钮一样。

@IBAction func back(_ sender: Any) {
    print(self.navigationController?.children)
    print(self.navigationController?.viewControllers)
    var array = self.navigationController?.children
    array!.insert(ViewController(), at: array!.count - 1)
    navigationController?.setViewControllers(array!, animated: false)
    print(self.navigationController?.viewControllers)
}


Optional([<One.ViewController: 0x7f9a1b4021e0>, <One.ViewController: 0x7f9a1b520dc0>, <One.TwoViewController: 0x7f9a1b40e320>])
Optional([<One.ViewController: 0x7f9a1b4021e0>, <One.ViewController: 0x7f9a1b520dc0>, <One.TwoViewController: 0x7f9a1b40e320>])
Optional([<One.ViewController: 0x7f9a1b4021e0>, <One.ViewController: 0x7f9a1b520dc0>, <One.ViewController: 0x7f9a1b40cd10>, <One.TwoViewController: 0x7f9a1b40e320>])

它按预期工作。

这两种方法一个接一个地工作。

我认为navigationController?.setViewControllers在override func viewDidAppear(中工作，有点延迟。

什么是机制？

navigationController？.setViewControllers在方法viewDidAppear

0 个答案: