ios 什么是强属性
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What is the strong property attribute
提问by Chance Hudson
I am using the Xcode beta for developers, and am noticing some subtle differences. Among them is a new attribute for declared properties.
我正在为开发人员使用 Xcode 测试版，并注意到一些细微的差异。其中有一个用于声明属性的新属性。
@property(strong)IBOutlet NSArrayController *arrayControl;
My question is: what does the strong attribute mean?? Does it replace some older one, or is it something entirely new? I have searched through google and the developer documentation and havent been able to find anything. Until i know what it is i am hesitant to use it.
我的问题是：strong 属性是什么意思？它会取代一些旧的，还是全新的？我已经搜索过谷歌和开发人员文档，但没有找到任何东西。在我知道它是什么之前，我对使用它犹豫不决。
Thanks in advance
提前致谢
回答by Lily Ballard
It's a replacement for the retainattribute, as part of Objective-C Automated Reference Counting (ARC). In non-ARC code it's just a synonym for retain.
它是retain属性的替代品，作为Objective-C 自动引用计数 (ARC) 的一部分。在非 ARC 代码中，它只是retain.
回答by Hyman Farnandish
A strong reference is a reference to an object that stops it from being deallocated. In other words it creates a owner relationship. Whereas previously you would do this:
强引用是对阻止它被释放的对象的引用。换句话说，它创建了所有者关系。而以前你会这样做：
**// Non-ARC Compliant Declaration
@property(retain) NSObject *obj;**
Under ARC we do the following to ensure a class instance takes an ownership interest a referenced object (i.e. so it cannot be deallocated until the owner is).
在 ARC 下，我们执行以下操作以确保类实例获得引用对象的所有权权益（即，在所有者存在之前不能释放它）。
**// ARC Compliant Declaration
@property(strong) NSObject *obj;**
回答by sanjeev sharma
As we know, we cannot release any object in an ARC-based project in iOS 5. So when we want to retain any object for further use at a later stage and don't want ARC to remove the object from memory, then we set the property for the object as "Strong".
我们知道，在 iOS 5 中，我们不能在基于 ARC 的项目中释放任何对象。 所以当我们想要保留任何对象以供以后进一步使用并且不希望 ARC 从内存中删除对象时，那么我们设置对象的属性为“强”。
