OBJ-C和多维数组 [英] Obj-C and multi-dimensional arrays

问题描述

请告诉我处理的对象 - 多维数组的最佳方式？我读过的一切形式的创造NSArrays，采用C风格的数组NSArray的和STL有的甚至建议折腾和C ++风格的数组去....

Whats the best way to deal with multi-dimensional arrays in Obj-C? I've read everything form creating NSArray's of NSArrays, use C style arrays and some even suggested tossing in STL and go with c++ style arrays....

我在需要的对象的3维数组。是最好的东西NSArrays的NSArrays的NSArray的？这似乎令人费解。是否有任何对象，有可以处理n维数组在一个干净清晰的API？

I'm in the need of a 3 dimensional array of objects. Is the best thing a NSArray of NSArrays of NSArrays? That seems convoluted. Is there any object out there that can deal with n-dimensional arrays in a nice clean clear api?

一个干净，清晰的API例如：

A clean and clear api example:

obj = [MDArray getLayer: 1 atX: 10 atY: 10];
[MDArray setLayer: 1 atX: 10 atY: 10 withValue: object];

如果它的确与众不同，我的最终目标是为游戏地图数据。我已经习惯了的东西C形式，但我努力用OBJ-C（学习，我去）。

If it makes a difference, my end goal is map data for a game. I'm used to the C style of things, but am trying hard to use obj-c (learning as I go).

推荐答案

这是很自然的建议嵌套，但浪费时间，除非你需要的东西，可以做的稀疏数组。

It is natural to suggest nesting, but a waste of time unless you need something that can do sparse arrays.

一个更好的解决方案是创建一个NSMutableArray和NSNulls或NSPointerArray，它允许通过 setCount空值填充它。法

A better solution is to create an NSMutableArray and fill it with NSNulls or an NSPointerArray, which allows for nulls via the setCount: method.

然后，如果你需要，也就是说，能够在坐标（0..3,0..3,0..3）来处理的对象，也就是4 * 4 * 4（或64）插槽。

Then, if you need, say, to be able to handle objects at coordinates (0..3,0..3,0..3), that is 4*4*4 (or 64) slots.

从那里，把一个（X，Y，Z）坐标到阵列的时隙仅仅是一个乘法的事项; （1,2,3）在索引的对象（1 +（2×宽）+（3 *宽*高））。

From there, turning an (x,y,z) coord into a slot in the array is just a matter of multiplication; (1,2,3) is the object at index (1 + (2 * width) + (3 * width * height)).

这是数学的简单位避免了一堆额外的分配（和潜在的，你的额外拨款片段内存）。虽然我完全不prematurely优化，数学很简单，而分配的舞蹈是不是 - 这会更容易在第一时间实施

That simple bit of math avoids a bunch of extra allocations (and the potential that your extra allocations fragment memory). While I'm all for not prematurely optimizing, the math is straightforward whereas the allocation dance is not -- this'll be easier to implement in the first place.

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