performSegueWithIdentifier 的调用顺序 [英] Order of Calls on performSegueWithIdentifier

问题描述

当我调用 performSegueWithIdentifier: 之后，我将覆盖 prepareForSegue: 以便在我的目标视图控制器上设置一些属性.但是，我试图了解这里的操作顺序以确保它是安全的.

When I call performSegueWithIdentifier: I am overriding prepareForSegue: afterwards in order to set some properties on my destination view controller. However, I'm trying to understand the order of operations here to make sure it's safe.

我使用以下命令实例化目标视图控制器:

I instantiate the destination view controller with:

MyViewController *myVC = (MyViewController*)segue.destinationViewController;

之后，我在其上设置了一些属性 - 即，我初始化另一个处理加载不同 Web 视图的对象的创建，然后在该对象上设置属性:

Afterwards I set a few properties on it - namely, I initialize the creation of another object which handles loading different web views, and then set properties on that object:

[myVC setFormHandler:
    [[WebFormHandler alloc] initWithSelectedFormName:[self theFormName]]];

在目标控制器的 viewDidLoad: 中，然后查询此对象的属性，并使用它加载正确的 Web 视图.现在，我对哪个先发生感到有些困惑 - 属性的设置，或目标控制器上的 viewDidLoad:.是否可以肯定地说，在调用 viewDidLoad: 之前，视图控制器的属性总是会从 prepareForSegue: 设置?

In viewDidLoad: of my destination controller, I then query the properties on this object, and use this to load the correct web view. Now, I am slightly confused by which happens first - the setting of the properties, or viewDidLoad: on the destination controller. Can it be said for certain that the properties of the view controller will always be set from prepareForSegue: before the viewDidLoad: is called?

推荐答案

看起来您可能已经从其他帖子中找到了答案，但我只想补充一点说明.

It looks like you may have found your answer from that other post, but I just wanted to add one point of clarification.

标准流程是

performSegue -> prepare -> loadView(在目标控制器中)

performSegue -> prepare -> loadView (in destination controller)

但是，在 popover segue 中，目标视图在 prepareForSegue 调用之前加载.

However, in popover segues, the destination view is loaded prior to the prepareForSegue call.

注意:在 iOS 8 中不再是这种情况.在 iOS 8 中，在调用 prepareForSegue 时不会加载 popover segue 的视图.

NOTE: This is no longer the case in iOS 8. In iOS 8, popover segue's views are NOT loaded by the time prepareForSegue is called.

这篇关于performSegueWithIdentifier 的调用顺序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！