如果name是NSString，则_name和self.name有什么区别? [英] What is the difference between _name and self.name if name was a NSString

问题描述

如果我打电话

NSString *theNameToDisplay = _name;

或

NSString *theNameToDisplay = self.name;

我知道这可能是一个愚蠢的问题，但是我看到两个版本都使用了很多，并且在输出中没有发现差异吗?

I know it might be a silly question but I see both versions used a lot and I don't spot a difference in the output?

谢谢！

推荐答案

假定您在.m文件中具有这一行(并且没有任何替代方法可以直接访问_name)

Assume you have in your .m file this line (and don't have any overriden methods to direct access to _name)

@synthesize name = _name;

这意味着属性name(self.name)在尝试访问它时将使用变量_name.在这种情况下，self.name等于_name

It mean that property name (self.name) will use variable _name when you try to access it. In this case self.name is equal to _name

但是，如果您具有名称的动态属性，则如下所示:

But if you have dynamic property for name, something like this :

-(NSString)name{
    return @"1234";
}

然后有一个区别. self.name将始终返回1234，但_name不能等于此值.

then there is a difference. self.name will always return 1234, but _name can be not equal to this value.

示例:

_name = @"555";
NSLog(_name);
NSLog(self.name);

结果:

2012-02-09 14:27:49.931 ExampleApp[803:207] 555
2012-02-09 14:27:49.933 ExampleApp[803:207] 1234

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