objective-c NSMutableArray addObject 不起作用
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NSMutableArray addObject not working
提问by joec
I have declared an NSMutableArray *categoriesin my view controller .h file, and declared a property for it.
我已经NSMutableArray *categories在我的视图控制器 .h 文件中声明了一个，并为其声明了一个属性。
In the parser:foundCharacters:method of the NSXMLParserdelegate in my .m file, I have this code:
在我的 .m 文件parser:foundCharacters:中的NSXMLParser委托方法中，我有以下代码：
-(void)parser:(NSXMLParser *) parser foundCharacters:(NSString *)string
{
if (elementFound)
{
element = string;
[self.categories addObject:element];
}
}
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.
但是当我[self.categories addObject:element]在调试模式下进入该行后将鼠标悬停在该行上时，XCode 告诉我大小为 0x0, 0 个对象。我的 XML 文件中有 3 个元素，因此数组中应该有 3 个项目。
I'm missing something really obvious and I can't figure out what.
我错过了一些非常明显的东西，我无法弄清楚是什么。
回答by Joshua Nozzi
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:
“0x0”部分是内存地址。具体来说，“nil”，这意味着您的可变数组在调用时不存在。尝试在您的 -init 方法中创建它：
categories = [[NSMutableArray alloc] init];
Don't forget to release it in your -dealloc.
不要忘记在您的 -dealloc 中释放它。
回答by Vishal16
Initialize an empty array using
使用初始化一个空数组
categories = [NSMutableArray array];
The array class method are autoreleased so no need to release.
数组类方法是自动释放的，所以不需要释放。
