I am getting an issue cannot init a class object even after adding lines to the constructor such as

我得到一个问题,即使在向构造函数添加行之后也无法初始化类对象

self = [super init];

self = [[super init] alloc];

And I am not sure what to do.

我不知道该怎么做。

This is the specific error:

这是具体的错误:

file:///%3Cunknown%3E: test failure: -[LinkedListTest testAdd] failed: *** +[NList<0x8e14> init]: cannot init a class object.

@interface NList()
@property (weak, nonatomic, readwrite) NSObject *head;
@property (nonatomic,readwrite) NSInteger *size;
@end

@implementation NList
@synthesize size = _size;
- (id) init:(NSInteger *)size {
    //is this even necessary? I don't want object methods.. or do I ?
    if (self){
        _head = nil;
        _size = size;
    }
    return self;
}

@interface NList : NSObject
@property (nonatomic,readonly) NSInteger *size;
@property (weak, readonly, nonatomic) NSObject *head;

- (void)add:(NSObject *)node;

@end

test class

- (void)testAdd
{
    NList *testList = [[NList init] alloc];
   // Card *testCardOne = [[Card init] alloc];
   // [testList add:(testCardOne)];
    XCTAssertNotNil(testList.head);
}

I have tried adding the line

我试过添加该行

    self = [[super init] alloc];

to the constructor to no avail.

对构造函数无济于事。

No visible interfacce for nlist declares

nlist声明没有可见的接口

or self = [super init]

complains cannot init a class object!

抱怨无法初始化一个类对象!

EDIT

I realized that it is not asking me for the size! the constructor requires a size parameter...how do I do this! Ahh [looks up docs]

我意识到这不是问我的大小!构造函数需要一个size参数......我该怎么做!啊[查找文档]

2 个解决方案

#1

A few things.

一些东西。

You need a default constructor

您需要一个默认构造函数

- (id)init {
    self = [super init];
    if (self) {
        self.head = nil;
    }
    return self;
}

Now that you have a default constructor (that calls the superclasses constructor), you need a more specific one for your purposes.

既然您有一个默认构造函数(调用超类构造函数),您需要一个更具体的构造函数用于您的目的。

- (id)initWithSize:(int)size {
    self = [self init]; // sets head, calls super constructor.
    if (self) {
        self.size = size;
    }
    return self;
}

Edit: Note, the last one had to be in your .h file so it is visible. And also, when instantiating this class, call

编辑:注意,最后一个必须在您的.h文件中,以便它可见。而且,在实例化这个类时,请调用

NList *list = [[NList alloc] initWithSize:mySize];

NList * list = [[NList alloc] initWithSize:mySize];

#2

You're a little backwards.

你有点倒退了。

How about:

NList *testList = [[NList alloc] init:SIZE];

where size is the SIZE init you want to use.

其中size是您要使用的SIZE init。

Alloc comes before init when you're instantiating Objective-C objects.

当您实例化Objective-C对象时,Alloc在init之前出现。

#1