如何在构造函数中初始化 Objective-C 结构? [英] How to initialize an Objective-C struct in constructor?

问题描述

我在 Objective-C 上使用结构体来存储一些数据，如下所示:

I´m using a struct on Objective-C to store some data, something like this:

@interface Interface : NSObject
{
    // my Data
    struct Data
    {
        __unsafe_unretained BOOL isInit;
        __unsafe_unretained BOOL isRegister;
        __unsafe_unretained NSString* myValue;
        
       // Data() : isInit(false), isRegister(false), myValue(@"mYv4lue") {} // Constructor doesnt work
    };

    struct Data myData;  // Create Struct
}

但是我不能用构造函数编译.我希望在创建结构时这些值采用一些默认值.

But I can't compile with a constructor. I want the values take some default value when I create the struct.

我该怎么做?

推荐答案

Structs 没有初始化器，如果你想用一组特定的值创建一个结构体，你可以编写一个返回的函数，为你创建并初始化它:

Structs don't have initializers, if you want to create a struct with a particular set of values you could write a function that returns creates and initialises it for you:

例如

struct Data {
        BOOL isInit;
        BOOL isRegister;
        NSString* myValue;
};

Data MakeInitialData () {
    data Data;
    data.isInit = NO;
    data.isRegister = NO;
    data.myValue = @"mYv4lue";

    return data;
}

现在您可以获得正确设置的结构:

now you can get a correctly set up struct with:

Data newData = MakeInitialData();

不过，请注意；您似乎正在使用 ARC，它不适用于其中包含对象指针的结构.在这种情况下，建议只使用类而不是结构.

A note, though; you seem to be using ARC, which doesn't work well with structs that have object pointers in them. The recommendation in this case is to just use a class instead of a struct.

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