ios - ViewWillAppear 不执行代码

Question

我的 ViewWillAppear 方法中有这段代码，它只是将一组标签向下移出屏幕:

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)

    //Hide 1,3,5 RM labels
    oneRepMax.center.y += view.bounds.height
    threeRepMax.center.y += view.bounds.height
    fiveRepMax.center.y += view.bounds.height

}

所有 3 个标签都已正确链接到我的 Storyboard文件。当我运行该项目时，没有任何反应。

如果我将完全相同的代码复制到链接到按钮的方法中，它会按预期工作。

项目中没有其他任何东西，所以我很困惑为什么这不起作用。

我正在使用 Xcode 7 并遵循一个在 ViewWillAppearMethod 中工作的教程。 如下:

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)

    heading.center.x -= view.bounds.width
    username.center.x -= view.bounds.width
    password.center.x -= view.bounds.width
    loginButton.center.y += 30
    loginButton.alpha = 0



}

Answer 1

在所有标 checkout 现在屏幕上之前，您永远不知道边界。

尝试在 viewDidAppear 方法中做同样的事情。

来自文档:

This method is called after the completion of any drawing and animations involved in the initial appearance of the view. You can override this method to perform tasks appropriate for that time, such as work that should not interfere with the presentation animation, or starting an animation that you want to begin after the view appears.