Objective-C中的嵌套数组（NSMutableArray） [英] Nested arrays in Objective-C ( NSMutableArray )

问题描述

我想建立一个嵌套数组：首先，我创建一个PlayerItems数组，它将包含10个数组，每个数组包含项目对象，对应于游戏中每个玩家的清单。在指示的行，我得到以下错误：

错误：void valued不会被忽略，因为它应该是

这里的void值是什么？如果我使用 [[PlayerItems objectAtIndex：i] addObject：myitem] ，程序会编译但崩溃。如果我评论该行，它编译并运行确定。谢谢您的帮助！

  self.PlayerItems = [[NSMutableArray alloc] initWithCapacity：11]; 
 NSMutableArray * itemarray = [[NSMutableArray alloc] initWithCapacity：60]; 
 item * myitem = [[item alloc] init]; 
 item.kind = 1; 
 for（int i = 1; i <10; i ++）{
 itemarray = [[NSMutableArray alloc] initWithCapacity：60]; 
 [PlayerItems addObject：itemarray]; 
 for（int i2 = 1; i2 <50; i2 ++）{
 myitem = [[item alloc] init]; 
 myitem.kind = 1; 
 //错误发生在下面的行：
（（NSMutableArray *）[[PlayerItems objectAtIndex：i] addObject：myitem]）; 
} 
} 
  

解决方案

I将执行如下操作：

  self.playerItems = [[NSMutableArray alloc] initWithCapacity：11]; 
 
 NSMutableArray * itemArray; 
 Item * anItem; 
 for（int playerIndex = 1; playerIndex< = 10; playerIndex ++）
 {
 itemArray = [NSMutableArray arrayWithCapacity：60]; 
 [playerItems addObject：itemArray]; 
 
 for（int itemIndex = 1; itemIndex <= 50; itemIndex ++）
 {
 anItem = [[Item alloc] init]; 
 anItem.kind = 1; 
 [itemArray addObject：anItem]; 
 [anItem release]; 
} 
} 
  

注意， Cocoa中的内存管理，因为您的原始代码已满内存泄漏。它可能有点困难包装你的头，但一旦你学会了，它变成第二自然。非常值得努力。

更新：

这样做是创建一个 Player 类，并让每个 Player 管理自己的项目： p>

Player.h

  @interface Player ：NSObject 
 {
 NSMutableArray * items; 
} 
 @property（readonly）NSMutableArray * items; 
 @end 
  

Player.m b
$ b

  #importPlayer.h
 @implementation Player 
 
 @synthesize items; 
 
  - （id）init 
 {
 if（（self = [super init]）== nil）{return nil; } 
 
 items = [[NSMutableArray alloc] initWithCapacity：60]; 
 Item * anItem; 
 for（int itemIndex = 1; itemIndex <= 50; itemIndex ++）
 {
 anItem = [[Item alloc] init]; 
 anItem.kind = 1; 
 [items addObject：anItem]; 
 [anItem release]; 
} 
 
 return self; 
} 
 
  - （void）dealloc 
 {
 [items release]; 
 [super dealloc] 
} 
 
 @end 
  

strong>

  NSMutableArray * allPlayers = [[NSMutableArray alloc] initWithCapacity：11]; 
 
播放器* aPlayer; 
 for（int playerIndex = 1; playerIndex< = 10; playerIndex ++）
 {
 aPlayer = [[Player alloc] init]; 
 [allPlayers addObject：aPlayer]; 
 [aPlayer release]; 
} 
 
 ... 
 
 [allPlayers release]; 
  

I'm trying to build a nested array: First, I make a "PlayerItems" array which will contain 10 arrays, each containing item objects, corresponding to the inventories of each player in the game. On the indicated line, I get the following error:

error: void valued not ignored as it ought to be

What is the void value here? If I used [[PlayerItems objectAtIndex:i] addObject:myitem] instead, the program compiles but crashes. If I comment that line out, it compiles and runs OK. Thank you for your help!

self.PlayerItems = [[NSMutableArray alloc] initWithCapacity:11];
NSMutableArray *itemarray = [[NSMutableArray alloc] initWithCapacity:60];
item *myitem = [[item alloc] init];
item.kind = 1;
for (int i = 1; i < 10; i++) {
    itemarray = [[NSMutableArray alloc] initWithCapacity:60];
    [PlayerItems addObject:itemarray];
    for (int i2 = 1; i2 < 50; i2++) {
        myitem = [[item alloc] init];
        myitem.kind = 1;
        // The error occurs on the line below:
        ((NSMutableArray *) [[PlayerItems objectAtIndex:i] addObject:myitem]);
    }
}

解决方案

I would do it as follows:

self.playerItems = [[NSMutableArray alloc] initWithCapacity:11];

NSMutableArray * itemArray;
Item * anItem;
for (int playerIndex = 1; playerIndex <= 10; playerIndex++)
{
    itemArray = [NSMutableArray arrayWithCapacity:60];
    [playerItems addObject:itemArray];

    for (int itemIndex = 1; itemIndex <= 50; itemIndex++)
    {
        anItem = [[Item alloc] init];
        anItem.kind = 1;
        [itemArray addObject:anItem];
        [anItem release];
    }
}

As a side note, you should definitely read up on memory management in Cocoa, since your original code is full of memory leaks. It can be a bit difficult to wrap your head around at first, but once you learn it, it becomes second nature. Well worth the effort.

update:

A more object-oriented way to do this would be to create a Player class, and have each Player manage its own set of items:

Player.h

@interface Player : NSObject
{
    NSMutableArray * items;
}
@property (readonly) NSMutableArray * items;
@end

Player.m

#import "Player.h"
@implementation Player

@synthesize items;

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

    items = [[NSMutableArray alloc] initWithCapacity:60];
    Item * anItem;
    for (int itemIndex = 1; itemIndex <= 50; itemIndex++)
    {
        anItem = [[Item alloc] init];
        anItem.kind = 1;
        [items addObject:anItem];
        [anItem release];
    }

    return self;
}

- (void)dealloc
{
    [items release];
    [super dealloc];
}

@end

Elsewhere

NSMutableArray * allPlayers = [[NSMutableArray alloc] initWithCapacity:11];

Player * aPlayer;
for (int playerIndex = 1; playerIndex <= 10; playerIndex++)
{
    aPlayer = [[Player alloc] init];
    [allPlayers addObject:aPlayer];
    [aPlayer release];
}

...

[allPlayers release];

这篇关于Objective-C中的嵌套数组（NSMutableArray）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！