NSMutableArray addObject不起作用

问题描述

我在视图控制器.h文件中声明了NSMutableArray *categories，并为其声明了一个属性.

I have declared an NSMutableArray *categories in my view controller .h file, and declared a property for it.

在我的.m文件中NSXMLParser委托的parser:foundCharacters:方法中，我有以下代码:

In the parser:foundCharacters: method of the NSXMLParser delegate in my .m file, I have this code:

-(void)parser:(NSXMLParser *) parser foundCharacters:(NSString *)string
{
    if (elementFound)
    {
        element = string;
        [self.categories addObject:element];
    }
}

但是在调试模式下进入它后，当我将鼠标悬停在[self.categories addObject:element]行上时，XCode告诉我大小为0x0，即0个对象.我的XML文件中有3个元素，因此数组中应包含3个项目.

But when I hover over the [self.categories addObject:element] line after stepping into it in debug mode, XCode tells me the size is 0x0, 0 objects. There are 3 elements in my XML file so 3 items should be in the array.

我遗漏了一些非常明显的东西，我不知道是什么.

I'm missing something really obvious and I can't figure out what.

推荐答案

"0x0"部分是内存地址.具体来说，"nil"，这意味着您的可变数组在被调用时不存在.尝试在您的-init方法中创建它:

The "0x0" part is a memory address. Specifically, "nil", which means your mutable array doesn't exist at the time this is being called. Try creating it in your -init method:

categories = [[NSMutableArray alloc] init];

别忘了在您的-dealloc中释放它.

Don't forget to release it in your -dealloc.

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