下划线在Objective-C中的成员变量名称中表示什么？ [英] What does an underscore signify in the name of a member variable in Objective-C?

问题描述

可能重复：

在Objective C中使用下划线前缀属性名称

我是一名C / C ++开发人员，正在学习Objective-C。最近我开始在网上找到一个教程。代码如下：

I am a C/C++ developer and am learning Objective-C. Recently I started on a tutorial that I found on net. The code is as below:

@interface MapDemoAnnotation : NSObject <MKAnnotation> {
    CLLocationCoordinate2D _coordinate;
}

- (id)initWithCoordinate:(CLLocationCoordinate2D)coordinate;

@end

@implementation MapDemoAnnotation

@synthesize coordinate=_coordinate;

- (id)initWithCoordinate:(CLLocationCoordinate2D)coordinate {
    self = [super init];
    if (self != nil) {
        _coordinate = coordinate;
    }
    return self;
}

@end

任何人都可以向我解释一下声明的含义

Can anyone please explain me the meaning of the statement

@synthesize coordinate=_coordinate;

我知道 @synthesize 的含义。但无法理解完整的陈述。
_coordinate 是一个成员变量。但什么是坐标？声明在哪里？

I know the meaning of @synthesize. But could not understand the complete statement. _coordinate is a member variable. But what is coordinate? Where is it declared?

推荐答案

基本上，它对编译器没有任何意义。它只是在私有实例变量上使用的编码实践。如果你不使用它，你的代码不会破坏。

Basically, it doesn't mean anything to the compiler. It's just a coding practice used on private instance variables. Your code isn't going to break if you don't use it.

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