blocks|key|510778|text|看看-[UIStoryboard+instantiateViewControllerWithIdentifier:]的documentation。这允许您使用在IB+Attributes+Inspector中设置的标识符从情节提要实例化视图控制器：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|510779|​|510780|📷|atomic|510781|510782|编辑后添加示例代码：|510783|UIStoryboard+*mainStoryboard+=+[UIStoryboard+storyboardWithName:@"MainStoryboard"
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++bundle:+nil];

MyViewController+*controller+=+(MyViewController*)[mainStoryboard+
++++++++++++++++++++instantiateViewControllerWithIdentifier:+@"<Controller+ID>"];|code-block|syntax|javascript|510784|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/library/ios/documentation/UIKit/Reference/UIStoryboard_Class/Reference/Reference.html#//apple_ref/doc/uid/TP40010909-CH1-SW4|1|IMAGE|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/1741fae941b8f67db4576629a50f51a7.png|imageAlt^0|2|1K|1N|D|0|0|0|0|1|1|0|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@$9|19|A|1A|1|1B]]|E|$]]|$1|F|3|G|5|6|7|1C|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1D|8|@]|D|@$9|1E|A|1F|1|1G]]|E|$]]|$1|K|3|G|5|6|7|1H|8|@]|D|@]|E|$]]|$1|L|3|M|5|6|7|1I|8|@]|D|@]|E|$]]|$1|N|3|O|5|P|7|1J|8|@]|D|@]|E|$Q|R]]|$1|S|3|-4|5|6|7|1K|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]|10|$5|11|W|12|E|$13|14|15|-4]]]]

Have a look at the <a href="http://developer.apple.com/library/ios/documentation/UIKit/Reference/UIStoryboard_Class/Reference/Reference.html#//apple_ref/doc/uid/TP40010909-CH1-SW4" rel="noreferrer">documentation</a> for <code>-[UIStoryboard instantiateViewControllerWithIdentifier:]</code>. This allows you to instantiate a view controller from your storyboard using the identifier that you set in the IB Attributes Inspector:

<img src="https://i.stack.imgur.com/gzK2u.png" alt="enter image description here">

EDITED to add example code:

<pre><code>UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"MainStoryboard"
 bundle: nil];

MyViewController *controller = (MyViewController*)[mainStoryboard 
 instantiateViewControllerWithIdentifier: @"&lt;Controller ID&gt;"];
</code></pre>

blocks|key|727314|text|通常，系统应该使用故事板来处理视图控制器实例化。您想要的是通过获取对self.window.rootViewController的引用来遍历viewController层次结构，而不是初始化视图控制器，如果您正确设置了故事板，则视图控制器应该已经正确初始化。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|727315|所以，假设你的rootViewController是一个UINavigationController，然后你想要发送一些东西到它的顶层视图控制器，你可以在你的AppDelegate的didFinishLaunchingWithOptions中这样做|727316|UINavigationController+*nav+=+(UINavigationController+*)+self.window.rootViewController;
MyViewController+*myVC+=+(MyViewController+*)nav.topViewController;
myVC.data+=+self.data;|code-block|syntax|javascript|727317|在Swift中，if非常类似：|727318|let+nav+=+self.window.rootViewController+as!+UINavigationController;
let+myVC+=+nav.topViewController+as!+MyViewController
myVc.data+=+self.data|727319|你真的不应该使用应用程序委托中的storyboard+id来初始化视图控制器，除非你想绕过加载storyboard的正常方式，自己加载整个storyboard。如果你必须从AppDelegate初始化场景，你很可能做错了什么。我的意思是，想象一下，由于某些原因，你想要将数据发送到堆栈下面的视图控制器，AppDelegate不应该到达视图控制器堆栈来设置数据。这不关它的事。它的业务是rootViewController。让rootViewController处理它自己的子进程吧！因此，如果我通过在info.plist文件中删除对rootViewController的引用来绕过系统的正常情节提要加载过程，我最多只能使用instantiateViewControllerWithIdentifier:实例化它，如果它是一个容器，则可能是它的根目录，比如UINavigationController。您要避免的是实例化已经由故事板实例化的视图控制器。这是一个我经常看到的问题。简而言之，我不同意公认的答案。这是不正确的，除非海报意味着要从info.plist中删除序列图像板的加载，否则您将加载2个序列图像板，这没有任何意义。这可能不是内存泄漏，因为系统初始化了根场景并将其分配给窗口，但随后您再次实例化它并再次分配它。你的应用程序一开始就很糟糕！|727320|entityMap^0|Y|U|0|7|I|2J|T|0|0|0|0|8N|14|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|12|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|13|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|14|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|15|8|@$9|16|A|17|B|C]]|D|@]|E|$]]|$1|S|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|T|$]]

Generally, the system should be handling view controller instantiation with a storyboard. What you want is to traverse the viewController hierarchy by grabbing a reference to the <code>self.window.rootViewController</code> as opposed to initializing view controllers, which should already be initialized correctly if you've setup your storyboard properly. 

So, let's say your <code>rootViewController</code> is a UINavigationController and then you want to send something to its top view controller, you would do it like this in your AppDelegate's <code>didFinishLaunchingWithOptions</code>:

<pre><code>UINavigationController *nav = (UINavigationController *) self.window.rootViewController;
MyViewController *myVC = (MyViewController *)nav.topViewController;
myVC.data = self.data;
</code></pre>

In Swift if would be very similar:

<pre><code>let nav = self.window.rootViewController as! UINavigationController;
let myVC = nav.topViewController as! MyViewController
myVc.data = self.data
</code></pre>

You really shouldn't be initializing view controllers using storyboard id's from the app delegate unless you want to bypass the normal way storyboard is loaded and load the whole storyboard yourself. If you're having to initialize scenes from the AppDelegate you're most likely doing something wrong. I mean imagine you, for some reason, want to send data to a view controller way down the stack, the AppDelegate shouldn't be reaching way into the view controller stack to set data. That's not its business. It's business is the rootViewController. Let the rootViewController handle its own children! So, if I were bypassing the normal storyboard loading process by the system by removing references to it in the info.plist file, I would at most instantiate the rootViewController using <code>instantiateViewControllerWithIdentifier:</code>, and possibly its root if it is a container, like a UINavigationController. What you want to avoid is instantiating view controllers that have already been instantiated by the storyboard. This is a problem I see a lot. In short, I disagree with the accepted answer. It is incorrect unless the posters means to remove loading of the storyboard from the info.plist since you will have loaded 2 storyboards otherwise, which makes no sense. It's probably not a memory leak because the system initialized the root scene and assigned it to the window, but then you came along and instantiated it again and assigned it again. Your app is off to a pretty bad start!

blocks|key|727364|text|++++UIStoryboard+*+storyboard+=+[UIStoryboard+storyboardWithName:@"Tutorial"+bundle:nil];
++++self.window.rootViewController+=+[storyboard+instantiateInitialViewController];|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|727365|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code> UIStoryboard * storyboard = [UIStoryboard storyboardWithName:@"Tutorial" bundle:nil];
 self.window.rootViewController = [storyboard instantiateInitialViewController];
</code></pre>

consider the following scenario: I have a storyboard-based app. I add a ViewController object to the storyboard, add the class files for this ViewController into the project and specify the name of the new class in the IB identity inspector. Now how am I going to refer to this ViewController programmatically from the AppDelegate? I've made a variable with the relevant class and turned it into an IBOutlet property, but I don't see any way of being able to refer to the new ViewController in code - any attempt to ctrl-drag a connection doesn't work.

i.e. within the AppDelegate I can get to the base ViewController like this

<pre><code>(MyViewController*) self.window.rootViewController
</code></pre>

but how about any other ViewController contained within the storyboard?

Storyboard - refer to ViewController in AppDelegate

容器

Swift

考虑以下场景:我有一个基于故事板的应用程序。我将一个ViewController对象添加到情节提要中，将此ViewController的类文件添加到项目中，并在IB身份检查器中指定新类的名称。现在我该如何从AppDelegate中以编程方式引用这个ViewController呢？我已经使用相关的类创建了一个变量，并将其...

问情节提要-参考AppDelegate中的ViewController
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