blocks|key|759820|text|Xcode只是一个IDE+--它不应该对应用程序执行时发生的事情有任何影响。如果有区别，似乎更有可能是为不同的iOS版本构建的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|759821|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Xcode is just the IDE -- it shouldn't have any bearing on what happens when your app is executing. If there's a difference, it seems more likely that you're building for different iOS versions.

blocks|key|317816|text|在Apple+Developer+forums上进行研究之后，似乎Xcode4在某些情况下会创建bugged+Builder+NIB。其结果是应用程序的rootViewController被加载了两次，这真的搞砸了事情。加载到Xcode3中的同一项目不会出现这个问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|317817|在我的通用应用程序中，它只影响了iPad的NIB。iPhone没问题。|317818|我能够通过以下方式解决这个问题：|317819|317820|删除接口生成器中的rootViewController连接(这会导致应用程序加载主控制器的+viewDidLoad+(被加载两次的那个控制器)，然后手动分配window.rootViewController+=+nil)|unordered-list-item|style|CODE|317821|In|317822|317823|317824|到目前为止，这似乎达到了预期的效果。|317825|entityMap|0|LINK|mutability|MUTABLE|url|https://devforums.apple.com/message/407848^0|1|M|0|0|0|0|0|26|V|1|1|0|0|0^^$0|@$1|2|3|4|5|6|7|11|8|@]|9|@$A|12|B|13|1|14]]|C|$]]|$1|D|3|E|5|6|7|15|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|16|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|17|8|@]|9|@]|C|$]]|$1|I|3|J|5|K|7|18|8|@$A|19|B|1A|L|M]]|9|@]|C|$]]|$1|N|3|O|5|K|7|1B|8|@]|9|@]|C|$]]|$1|P|3|-4|5|6|7|1C|8|@]|9|@]|C|$]]|$1|Q|3|-4|5|6|7|1D|8|@]|9|@]|C|$]]|$1|R|3|S|5|6|7|1E|8|@]|9|@]|C|$]]|$1|T|3|-4|5|6|7|1F|8|@]|9|@]|C|$]]]|U|$V|$5|W|X|Y|C|$Z|10]]]]

After researching this on the <a href="https://devforums.apple.com/message/407848" rel="nofollow">Apple Developer forums</a>, it seems that in some cases Xcode 4 creates bugged Interface Builder NIBs. The effect is that the application's rootViewController gets loaded in twice, which really screws things up. The same project loaded in Xcode 3 won't exhibit the problem.

In my universal app, it only affected the iPad NIB. The iPhone was fine.

I was able to solve this issue by:

<ul>
<li>Removing the rootViewController connection in Interface Builder (this causes the app to load with <code>window.rootViewController = nil</code>)</li>
<li>In viewDidLoad for the main controller (the one that was being loaded twice), I then manually assign <code>appDelegate.window.rootViewController = self</code></li>
</ul>

So far this seems to have the desired effect.

blocks|key|4098601|text|你有没有设置视图控制器的视图？我也有同样的问题，我意识到我没有设置view属性。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4098602|-+(void)viewDidLoad+{
++++UIView+*contentView+=+[[UIView+alloc]+initWithFrame:+[[UIScreen+mainScreen]+applicationFrame];
++++//add+some+stuff+to+contentView+here
++++self.view+=+contentView;
++++[contentView+release];
}|code-block|syntax|javascript|4098603|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Did you set the view of the view controller? I had the same issue and I realized that I didn't set the view property.

<pre><code>- (void)viewDidLoad {
 UIView *contentView = [[UIView alloc] initWithFrame: [[UIScreen mainScreen] applicationFrame];
 //add some stuff to contentView here
 self.view = contentView;
 [contentView release];
}
</code></pre>

blocks|key|759887|text|我也有同样的问题。我解决了这个问题。当你的应用程序内存收到内存警告时，就会发生这种情况。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|759888|将断点放到memoryDidReceiveWarning。它会被调用，并清除你的类对象内存。所以你的viewDidLoad被调用了两次，因为当时它没有内存。|759889|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

I had same issue. And i resolved it. It happens when your app memory did get memory warning.

Put a breakpoint to memoryDidReceiveWarning. It get's called, and clear your class object memory. So your viewDidLoad Get called twice, because it has no memory at that time.

Is anyone else having issues with Xcode 4 where <code>viewDidLoad</code> is being called twice? I have run the same project in both Xcode 3.2 and Xcode 4 and it only acts up in Xcode 4.

Xcode 4 - viewDidLoad issue

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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在viewDidLoad被调用两次的情况下，是否有人对Xcode4有问题？我在Xcode3.2和Xcode4中运行了相同的项目，它只在Xcode4中运行。

问Xcode 4- viewDidLoad问题
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