无法向NSMutableArray ivar添加项目 [英] Cannot add items to an NSMutableArray ivar

问题描述

我的目标是在数组中添加一个字符串，我在一个方法中调用。

在这个方法中，数组，不知道为什么。我在类的开始有这个：

  NSMutableArray * listOfEvents; 
  

以及我针对每个事件调用的方法：

   - （void）EventList 
 {
 [listOfEvents addObject：@ran]; 
 NSLog（@％@，listOfEvents）; 
} 
  

我得到（null）如果我把数组定义 NSMutableArray * listOfEvents; 放在函数体中，I每次获取字符串值 @ran，所以数组总是只有一个值，而不是有许多字符串 @ran 。

这有什么问题？似乎我不能理解数组的一些东西，虽然我已经读了这些文档多次。

解决方案

假设您尚未初始化 listOfEvents 。

确保您执行 listOfEvents =在你的类的 init 方法中的[[NSMutableArray alloc] init]; 还要确保你在类的 dealloc 方法中释放它。

My goal is to add a string to array, and I do that in a method which I call.

In this method, I get a null value in the array, and don't know why. I have this at the start of my class:

NSMutableArray *listOfEvents;

and a method which I call on each event:

-(void)EventList
{
    [listOfEvents addObject:@"ran"];
    NSLog(@"%@", listOfEvents);     
}

I get (null) in the log.

If I put the array definition NSMutableArray *listOfEvents; in the function body, I get the string value @"ran", each time, so the array always has only one value, instead of having many strings named @"ran".

What's wrong with this? It seems that I can't understand something about arrays, even though I have read the documents a number of times.

解决方案

I'm assuming you haven't initialized listOfEvents.

Make sure you do listOfEvents = [[NSMutableArray alloc] init]; in your class's init method. Also make sure you release it in your class's dealloc method.

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