blocks|key|2846910|text|可以，如果发生内存警告，它可能会被卸载。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2846911|至于viewDidUnload和dealloc之间的区别--前者是在视图被卸载时调用的，通常是因为内存不足的情况。后者在对象的保留计数达到零时调用(即完全从内存中释放)|2846912|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|$]]

Yes, it could be unloaded if a memory warning occurs.

As for the difference between viewDidUnload and dealloc - the former is called when your view is unloaded, typically because of a low memory situation. The latter is called when your object's retain count reaches zero (i.e. it is completely released from memory)

blocks|key|2847099|text|viewDidUnload+:当视图控制器需要释放其视图和与该视图关联的任何对象以释放内存时，在内存不足的情况下调用。More|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2847100|释放释放：释放接收方占用的内存，通过+NSObject协议方法间接调用对象的释放方法。More|2847101|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/library/ios/#documentation/uikit/reference/UIViewController_Class/Reference/Reference.html#//apple_ref/occ/instm/UIViewController/viewDidUnload|1|http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSObject_Class/Reference/Reference.html^0|0|1M|1N|4|0|0|I|T|17|4|1|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@$9|U|A|V|1|W]]|E|$]]|$1|F|3|G|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@$9|10|A|11|1|12]]|E|$]]|$1|H|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]|P|$5|K|L|M|E|$N|Q]]]]

viewDidUnload : called during low-memory conditions when the view controller needs to release its view and any objects associated with that view to free up memory. <a href="http://developer.apple.com/library/ios/#documentation/uikit/reference/UIViewController_Class/Reference/Reference.html#//apple_ref/occ/instm/UIViewController/viewDidUnload" rel="nofollow">More</a>

dealloc: Deallocates the memory occupied by the receiver, An object’s dealloc method is invoked indirectly through the release NSObject protocol method. <a href="http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSObject_Class/Reference/Reference.html" rel="nofollow">More</a>

blocks|key|2562760|text|UIViewController永远不会卸载。他们拥有的UIView可以是。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2562761|因此，如果您的问题是，尽管UIView的控制器已被推送到导航控制器，但它是否可以卸载，答案是肯定的。只有当前显示的UIView不会被卸载(如果您不阻止卸载机制工作的话)。|2562762|此外，viewDidUnload是在UIViewController管理的视图已卸载时发送给它的消息，这通常与解除分配视图不同。事实上，当一个视图实际被释放时，它肯定会被卸载，但不会发送viewDidUnload。|2562763|entityMap^0|0|G|S|6|0|0|3|D|2L|D|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|K|$]]

<code>UIViewController</code>s are never unloaded. The <code>UIView</code>s they own can be.

So, if you question is if a UIView can be unloaded although its controller has been pushed on to the navigation controller, the answer is yes. Only the currently displayed UIView will not be unloaded (if you don't prevent the unloading mechanism from working).

Furthermore, <code>viewDidUnload</code> is a message that is sent to a UIViewController when the view it manages has been unloaded, which usually is not the same as deallocating the view. In fact, when a view is actually deallocated, it is unloaded for sure, but <code>viewDidUnload</code> is not sent.

blocks|key|2847032|text|将不会取消分配已推入nav控制器堆栈且尚未弹出的UIViewController。但是，它的view属性可能会被卸载--特别是，如果出现内存不足的情况，并且该视图控制器的视图当前不可见(某些东西正在覆盖它，如模式对话框，或在其上面推送的另一个VC+)，则系统可能会卸载该视图。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2847033|对于这个方法所做的事情来说，viewDidUnload是一个不好的名字。当内存不足导致视图被卸载时，就会调用它--也就是说，它不是与viewDidLoad相反的方法，我认为您可能会合理地预期到这一点。|2847034|更多信息：|2847035|When+should+I+release+objects+in+-(void)viewDidUnload+rather+than+in+-dealloc?|2847036|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/1158788/when-should-i-release-objects-in-voidviewdidunload-rather-than-in-dealloc^0|1A|4|0|E|D|1U|B|0|0|0|26|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|11|8|@]|D|@]|E|$]]|$1|J|3|K|5|6|7|12|8|@]|D|@$9|13|A|14|1|15]]|E|$]]|$1|L|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|M|$N|$5|O|P|Q|E|$R|S]]]]

A UIViewController that has been pushed onto a nav controller stack, and hasn't yet been popped, will not be dealloc'd. However, its <code>view</code> property may be unloaded -- in particular, if a low memory condition occurs AND the view for that view controller isn't currently visible (something is covering it, like a modal dialog, or another VC pushed on top of it), the view may be unloaded by the system. 

<code>viewDidUnload</code> is a bad name for what the method does. It is called when a low memory condition caused the view to be unloaded -- i.e. it is not the 'opposite' method to <code>viewDidLoad</code>, which I think you might reasonably expect. 

More info:

<a href="https://stackoverflow.com/questions/1158788/when-should-i-release-objects-in-voidviewdidunload-rather-than-in-dealloc">When should I release objects in -(void)viewDidUnload rather than in -dealloc?</a>

blocks|key|2562929|text|同样重要的是，在viewDidUnload之后将再次调用viewDidLoad。如果您在viewDidLoad中执行设置，则应该以这样的方式处理它，即第二次调用它不会导致内存泄漏。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2562930|要么拆除viewDidUnload中的所有东西(如果它们是内存密集型的，这是礼貌的)，要么在设置它们时检查它们的存在，并且不要重复执行两次。(当然，还要在dealloc方法之前或过程中完全销毁它们。)|2562931|你不能保证viewDidUnload会在dealloc之前被调用。|2562932|entityMap^0|8|D|S|B|18|B|0|4|D|25|7|0|5|D|K|7|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|K|$]]

Also important is that <code>viewDidLoad</code> will be called again after <code>viewDidUnload</code>. If you perform setup in <code>viewDidLoad</code>, you should deal with it in such a way that a second call to it will not cause memory leaks.

Either tear everything down in <code>viewDidUnload</code> (polite, if they are memory intensive), or check for their existence when you set them up and don't do it twice. (And, of course, totally tear them down before or during the <code>dealloc</code> method.)

You are not guaranteed that <code>viewDidUnload</code> will be invoked before <code>dealloc</code> is.

Also would anybody tell me what's the difference between viewDidUnload and dealloc?

Would a UIViewController currently in UINavigationContoller's viewController stack be unloaded?

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。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

还有人能告诉我viewDidUnload和dealloc有什么区别吗？

问当前在UINavigationContoller的viewController堆栈中的UIViewController是否会被卸载？
EN

回答 5

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问当前在UINavigationContoller的viewController堆栈中的UIViewController是否会被卸载？EN

回答 5

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问当前在UINavigationContoller的viewController堆栈中的UIViewController是否会被卸载？
EN