是什么与showViewController的编程相反：sender： [英] Whats the programmatic opposite of showViewController:sender:

问题描述

我正在编写一个仅限iOS 8的应用程序，我正在使用Show和Show Detailsegue以及 showViewController：sender：和 showDetailViewController：sender：方法。

I'm writing an iOS 8 only app and I'm using the new adaptive presentations using a combination of the "Show" and the "Show Detail" segue and the showViewController:sender: and showDetailViewController:sender: methods.

我的问题是在调用 showViewController：sender：之后返回的编程方式是什么？视图控制器的显示方式取决于其父上下文。例如。在 UINavigationController showViewController：sender：将新控制器推送到导航堆栈但是如果没有UIKit容器查看控制器图表然后 showViewController：sender：最后做一个演示文稿。

My question is what is the programatic way to go back after calling showViewController:sender:? The way the view controller is shown depends on its parent context. E.g. in a UINavigationController showViewController:sender: pushes a new controller onto the navigation stack but if there is no UIKit container in the view controller graph then showViewController:sender: ends up doing a presentation instead.

考虑到我可以编写自己的任意容器控制器，检查

Considering i could write my own arbitrary container controller it seems unfeasible to check

if (self.navigationController) {
    [self.navigationController popViewControllerAnimated:YES];
}
else if (self.presentingViewController){
...
else if ([self.parentViewController isKindOfClass:[CrazyCustomContainer class]]){
    [self.parentViewController someWackyUnwindMethod];
}
...

等...所以有一个通用的反转显示的方式？如果不是我看到的唯一解决方案是使用展开segue的一切。没有太多的麻烦，但我很好奇。

etc... so is there a generic way to reverse being shown? If not the only solution i see is to use unwind segues for everything. Not too much of a hassle but I'm curious.

推荐答案

有一章关于如何 showViewController ：sender：和 showDetailViewController：sender：在编程iOS 8：深入视图，视图控制器和框架。

调用这些方法时，它们调用 targetViewControllerForAction：sender ：自己并在返回的对象上调用此方法。然后，目标对象可以以适当的方式显示视图控制器。例如，导航控制器在其导航堆栈上推送视图控制器。

When these methods are called, they call targetViewControllerForAction:sender: on themselves and call this method on the returned object. The target object can then display the view controller in an appropriate way. For example, a navigation controller pushes the view controller on its navigation stack.

因此，您可以创建泛型 dismissVC：方法并在不同的 UIViewController 子类中覆盖它。

So you can create a generic dismissVC: method and override it in different UIViewController subclasses.

extension UIViewController {
    func dismissVC(sender:AnyObject?) {
        if let presentingVC = targetViewControllerForAction("dismissVC", withSender: sender) as? UIViewController {
            presentingVC.dismissVC(self)
        }
    }
}

extension UINavigationController {
    override func dismissVC(sender: AnyObject?) {
        popViewControllerAnimated(true)
    }
}

extension CrazyCustomContainer {
    override func dismissVC(sender: AnyObject?) {
        someWackyUnwindMethod()
    }
}

这样，当你打电话给 dismissVC：方法，如果总是根据上下文正确地关闭视图控制器。

This way, when you call dismissVC: method, if will always correctly dismiss the view controller depending on the context.

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