目标C - 声明错误 - 请解释

问题描述

@interface Connections()
{
   static Connections *this;
}
@end

.m文件中的上述代码丢弃编译器错误

The above piece of code in .m file throwing compiler error

同时

关键字被删除它运作良好 - 这是显而易见的。
目的：我想要连接实例静态和私有。

key word is removed it works well - which so obvious.Purpose : I want "Connections" instance static and private.

为什么会出现这种情况，请帮忙。

Why is this behavior, please help.

推荐答案

您不能在Objective-C类中声明类级变量;相反，你需要在实现文件中隐藏它们，通常给它们 static -scope，这样它们就无法从外部访问。

You cannot declare class-level variables in Objective-C classes; instead you need to "hide" them in the implementation file, often giving them static-scope so they cannot be accessed externally.

Connections.m：

Connections.m:

#import "Connections.h"

static Connections *_sharedInstance = nil;

@implementation Connections

...

@end

如果这是一个单例，你通常会定义一个类级访问器来在第一次使用时创建单例：

And if this is a singleton, you typically define a class-level accessor to create the singleton upon first use:

+ (Connections *)sharedInstance
{
    if (_sharedInstance == nil)
    {
        _sharedInstance = [[Connections alloc] init];
    }
    return _sharedInstance;
}

（你需要在.h文件中添加声明） ：

(and you'll need to add the declaration in the .h file):

+ (Connections *)sharedInstance;

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