_variable&的区别是什么？ Objective.C中的self.variable？ [英] What's the difference between _variable & self.variable in Objective-C?

问题描述

我对Objective C和iOS很陌生，目前正在尝试使用iOS 6 SDK学习应用程序开发。我真的无法理解的一个概念是在.m文件中访问时_variable和self.variable之间的区别。它们是一样的吗？或者不同？

I am quite new to Objective C and iOS, currently trying to learn app development using the iOS 6 SDK. One concept I really can't wrap my head around is the difference between "_variable" and "self.variable" when being accessed in the .m file. Are they the same? Or different?

以下是一个简单的样本

MyClass.h

MyClass.h

#import <Foundation/Foundation.h>

@interface MyClass : NSObject
@property (strong, nonatomic) NSString *myName;
@end

MyClass.m

MyClass.m

#import "MyClass.h"

@interface MyClass ()
@property (nonatomic, strong) NSString *anotherName; 
@end

@implementation MyClass
- (void) myFunction {
    _myName = @"Ares";
    self.myName = @"Ares";

    _anotherName = @"Michael";
    self.anotherName = @"Michael";
}
@end

因此上述实施方式有所不同设置一个变量？
变量myName是公开的，而anotherName是私有的。

So is there a difference in the above implementations to set a variable? Variable "myName" is Public while "anotherName" is Private.

非常感谢任何输入。谢谢！

Would greatly appreciate any inputs. Thanks!

推荐答案

区别在于：

变量名称 _ 是实例变量。

the variable names with _ are instance variables.

self.variable 正在对象上调用getter方法。

self.variable is calling a getter method on your object.

在您的示例中，实例变量是自动生成的，您也不需要合成属性。

In your example, the instance variables are automatically generated and you don't need to synthesize your properties either.

您的示例中真正重要的区别在于如果你没有使用ARC，那就进入游戏 -

The real important difference in your example comes into play if you are not using ARC-

self.variable 如果你标记的话，将为你保留一个对象属性保留或 strong
_variable 根本不解决内存管理问题

self.variable will retain an object for you if you mark the property with retain or strong _variable does not address memory management at all

这篇关于_variable&的区别是什么？ Objective.C中的self.variable？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！