最佳的方式来初始化变化的对象 [英] Optimal way to initialize varying objects

问题描述

我要初始化很多不同类型的基于整数参数的对象的。它们都具有相同的总体初始化方法。

I have to initialize a lot of different types of objects based on an integer parameter. They all have the same overall initialization methods.

目前，我有以下的code

At the moment I have the following code

#def APPLE 1
#def PEAR 2
switch (t)
{
    case APPLE:
      newobj = [[FApple alloc] init];
      break;
    case PEAR:
      newobj = [[FPear] alloc] init];
      break;
    default:
      retobj = nil;
}

我相信一定会有更好的方式来做到这一点。当我添加FOrange我必须去这里添加另一行。

I believe there must be a better way to do this. When I add FOrange I have to go and add another line here.

这将是一个更好的办法？

What would be a better way?

推荐答案

您需要一个映射的数字 - >键入的地方，但你并不需要重复code：

You need a mapping number -> type somewhere, but you don't need to repeat the code:

NSDictionary* d = [NSDictionary dictionaryWithObjectsAndKeys:
                   [FPear  class], [NSNumber numberWithInt:PEAR ],
                   [FApple class], [NSNumber numberWithInt:APPLE],
                   nil];    

Class c = [d objectForKey:[NSNumber numberWithInt:t]];
id x = [[c alloc] init];

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