关于retain 、readonly、readwrite、copy、assign的详细介绍
iphone开发一定会遇到
@property (retain, nonatomic) IBOutlet UITextView *descText;
其中的retain 还可以填写为其他如readonly、retain、read write、copy、assign等属性。
具体代表的意思下面列出：
retain? ?When you’re dealing with object values. The compiler?will retain the value you pass in (we’ll talk more about?retaining in a minute) and release the old value when a?new one comes in.
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readonly ??When you don’t want people modifying the property.You can still change the field value backing the
property, but the compiler won’t generate a setter.
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readwrite? ?When you want the property to be modifiable by?people. The compiler will generate a getter and a??setter for you. This is the default.
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copy ? ? ? ? ? ??When you want to hold onto a copy of some value?instead of the value itself; for example, if you want?to hold onto an array and don’t want people to be able?to change its contents after they set it. This sends a?copy message to the value passed in then retains that.
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assign ? ? ? When you’re dealing with basic types, like ints, floats,?etc. The compiler just creates a setter with a simple?myField = value statement. This is the default, but?not usually what you want.
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