属性也声明为实例变量吗? [英] Properties declared as instance variables too?

问题描述

此代码有效:

    @interface StringStuff : NSObject {

    }
    @property (nonatomic, retain) NSString *String1;
    @property (nonatomic, retain) NSString *String2;

    - (NSString *) doSomethingWithStrings;

    @end

但是我经常看到:

        @interface StringStuff : NSObject {
             NSString *String1;
             NSSTring *String2;    
        }
        @property (nonatomic, retain) NSString *String1;
        @property (nonatomic, retain) NSString *String2;

        - (NSString *) doSomethingWithStrings;

        @end

是否也经常将属性声明为实例变量?它只是被认为是好的形式吗?

Is there a reason that properties are often declared as an instance variable as well? Is it just considered good form?

推荐答案

旧版；过去(现在仍然在32位Mac OS X目标代码上)需要ivar声明.在iOS，模拟器和64位OS X上不再如此.

Legacy; it used to be (and still is on 32 bit Mac OS X targeted code) that the ivar declarations were required. That is no longer true on iOS, the simulator and 64 bit OS X.

请注意，在确实需要self.iVar的情况下，@synthesize iVar = iVar_;可以防止意外的直接访问.

Note that it is common to @synthesize iVar = iVar_; to prevent accidental direct access where self.iVar is really required.

这篇关于属性也声明为实例变量吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！