blocks|key|192120|text|澄清：将保留和释放视为增量；对于每个隐含保留的语句，您必须有一个平衡释放。保留是一个“保持这个对象存活，直到平衡释放”的语句。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|192121|差不多；你需要(假设是@property(retain)+UITextField+*textField;)：|CODE|192122|+textField+=+[[UITextField+alloc]+init];+//+%2B1+retain|code-block|syntax|javascript|192123|或者：|192124|+self.textField+=+[[[UITextField+alloc]+init]+autorelease];+//+%2B1,+%2B1,+-1+(delayed)|192125|唯一不同的是，上面的赋值是直接赋值的，不使用setter来保留对象。|192126|如果您要执行以下操作：|192127|+self.textField+=+[[UITextField+alloc]+init];+//+%2B1+%2B1|192128|你会泄漏对象的。|192129|是的，在所有正确的情况下，您需要：|192130|self.textField+=+nil;|192131|192132|[textField+release];|192133|在你的dealloc里。|192134|192135|哦，对不起，我错过了第二个@property声明中的assign。|192136|简而言之，不要这么做。它是一个弱引用，很容易变得摇摆不定。它有它的用法，不幸的是，它们比正常情况下更常见(最常见的是对象图中的银行指针，尽管委托也使用它们)。我上面写的仍然有效；考虑保留为增量，在assign的情况下，没有%2B1，也没有要平衡的东西。|192137|但是，在这种情况下，assign也很可能是不正确的；您应该使用retain。您可以使用assign并在外部管理保留/释放，但这既不典型，也非常脆弱。属性上的retain专门用来表示所有权！|192138|entityMap^0|3|1O|0|B|15|0|0|0|0|0|0|0|0|0|0|0|0|3|7|0|0|D|9|Q|6|0|2Q|6|0|A|6|V|6|17|6|26|6|0^^$0|@$1|2|3|4|5|6|7|1H|8|@$9|1I|A|1J|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1K|8|@$9|1L|A|1M|B|H]]|D|@]|E|$]]|$1|I|3|J|5|K|7|1N|8|@]|D|@]|E|$L|M]]|$1|N|3|O|5|6|7|1O|8|@]|D|@]|E|$]]|$1|P|3|Q|5|K|7|1P|8|@]|D|@]|E|$L|M]]|$1|R|3|S|5|6|7|1Q|8|@]|D|@]|E|$]]|$1|T|3|U|5|6|7|1R|8|@]|D|@]|E|$]]|$1|V|3|W|5|K|7|1S|8|@]|D|@]|E|$L|M]]|$1|X|3|Y|5|6|7|1T|8|@]|D|@]|E|$]]|$1|Z|3|10|5|6|7|1U|8|@]|D|@]|E|$]]|$1|11|3|12|5|K|7|1V|8|@]|D|@]|E|$L|M]]|$1|13|3|O|5|6|7|1W|8|@]|D|@]|E|$]]|$1|14|3|15|5|K|7|1X|8|@]|D|@]|E|$L|M]]|$1|16|3|17|5|6|7|1Y|8|@$9|1Z|A|20|B|H]]|D|@]|E|$]]|$1|18|3|-4|5|6|7|21|8|@]|D|@]|E|$]]|$1|19|3|1A|5|6|7|22|8|@$9|23|A|24|B|H]|$9|25|A|26|B|H]]|D|@]|E|$]]|$1|1B|3|1C|5|6|7|27|8|@$9|28|A|29|B|H]]|D|@]|E|$]]|$1|1D|3|1E|5|6|7|2A|8|@$9|2B|A|2C|B|H]|$9|2D|A|2E|B|H]|$9|2F|A|2G|B|H]|$9|2H|A|2I|B|H]]|D|@]|E|$]]|$1|1F|3|-4|5|6|7|2J|8|@]|D|@]|E|$]]]|1G|$]]

Clarification: Think of retains and releases as deltas; for every statement that implies a retain, you must have a balancing release. A retain is a statement of "keep this object alive until the balancing release".

Almost; you'd need (assuming <code>@property(retain) UITextField *textField;</code>):

<pre><code> textField = [[UITextField alloc] init]; // +1 retain
</code></pre>

Or:

<pre><code> self.textField = [[[UITextField alloc] init] autorelease]; // +1, +1, -1 (delayed)
</code></pre>

The only difference being that the above is a direct assignment and does not use the setter to retain the object.

If you were to do:

<pre><code> self.textField = [[UITextField alloc] init]; // +1 +1
</code></pre>

You'd leak the object.

And, yes, in all correct cases, you need to either:

<pre><code>self.textField = nil;
</code></pre>

Or:

<pre><code>[textField release];
</code></pre>

In your <code>dealloc</code>. 

<hr/>

Oh -- I'm sorry -- I missed the <code>assign</code> on that second <code>@property</code> declaration.

In short, don't do that. It is a weak reference and can easily become dangling. It has its uses and, sadly, they are more common than they should be (bank pointers in object graphs, most commonly, though delegates use 'em too). What I wrote above still stands; consider retains as a delta and, in the case of <code>assign</code>, there is no +1 and nothing to balance.

But, in this case, <code>assign</code> is also most likely incorrect; you'd want <code>retain</code>. You could use <code>assign</code> and manage the retain/release externally, but that is both atypical and rife with fragility. <code>retain</code> on properties exists specifically to express ownership!

blocks|key|3819839|text|@property+(nonatomic,+assign)+UITextField+*textField;

self.textField+=+[[UITextField+alloc]+init];|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3819840|来自@bbum答案的评论：|unstyled|3819841|我没有保留的|3819842|。我做了财产保险。赋值后保留计数为1。我只需要在dealloc中释放一次。|blockquote|3819843|3819844|3819845|不要这样做！|offset|length|style|BOLD|3819846|好的，如果在两者之间没有发生任何事情，就不会泄漏(属性是assign!)但这违背了对象所有权的基本原理。|CODE|3819847|标记为assign的属性用于您不拥有委托的对象，例如。因此，根据内存管理规则：您不能放弃您不拥有的对象的所有权。|3819848|这样做，你会遇到很多麻烦，因为你依赖于实现细节，你知道你创建了对象，你需要释放它。你不会想把自己放在那个位置的。如果您稍后设置了另一个对象呢？您可能会泄露前者，并可能过度释放后者，从而导致潜在的崩溃。|3819849|entityMap^0|0|0|0|0|0|0|0|6|0|S|6|0|3|6|13|H|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|13|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|14|8|@]|9|@]|A|$]]|$1|I|3|J|5|K|7|15|8|@]|9|@]|A|$]]|$1|L|3|-4|5|F|7|16|8|@]|9|@]|A|$]]|$1|M|3|-4|5|F|7|17|8|@]|9|@]|A|$]]|$1|N|3|O|5|F|7|18|8|@$P|19|Q|1A|R|S]]|9|@]|A|$]]|$1|T|3|U|5|F|7|1B|8|@$P|1C|Q|1D|R|V]]|9|@]|A|$]]|$1|W|3|X|5|F|7|1E|8|@$P|1F|Q|1G|R|V]|$P|1H|Q|1I|R|S]]|9|@]|A|$]]|$1|Y|3|Z|5|F|7|1J|8|@]|9|@]|A|$]]|$1|10|3|-4|5|F|7|1K|8|@]|9|@]|A|$]]]|11|$]]

<pre><code>@property (nonatomic, assign) UITextField *textField;

self.textField = [[UITextField alloc] init];
</code></pre>

From comment on @bbum answer:

<blockquote>
 I didn't retain. I assinged in property. Retain count is 1 after
 assignment. I just need release one time in dealloc.
</blockquote>

Don't do this!

Ok, that wouldn't leak if nothing happened in between (the property is <code>assign</code>!) but this goes against the basics of Object Ownership. 

The properties marked as <code>assign</code> are used for objects you don’t own, e.g., delegates. Therefore, according to the Memory Management Rules: You must not relinquish ownership of an object you do not own.

By doing this, you will get into lots of trouble because you are relying on an implementation detail, the fact that you know that you created the object and you need to release it. You do not want to put yourself in that position. What if you later set another object? You would leak the former and probably over-release the later, leading to a potential crash.

<pre><code>@interface MyViewController : UIViewController {
 UITextField *textField;
}
@property (nonatomic, retain) UITextField *textField;

UITextField *aTextField = [[UITextField alloc] init]; 
self.textField = aTextField;
[aTextField release]; 
</code></pre>

I don't know why <code>aTextField</code> is necessary. Can't I write it like this?

<pre><code>@property (nonatomic, assign) UITextField *textField;

self.textField = [[UITextField alloc] init]; 
</code></pre>

Why is the temporary variable necessary when allocating?

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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@interface MyViewController : UIViewController {    UITextField *textField;}@property (nonatomic, retain) UITextField *textField;UITextField *aTextField = [[UIT...

问为什么临时变量在分配时是必需的？
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问为什么临时变量在分配时是必需的？EN