有没有办法迭代字典？

问题描述

我知道 NSDictionaries ，你需要一个键来得到一个值。但是我怎样才能迭代 NSDictionary 键和值 c>，以便我知道哪些键，哪些是什么值？我知道在 JavaScript 中有一个叫做 for-in-loop 的东西。是否有类似于 Objective-C ？

I know NSDictionaries as something where you need a key in order to get a value. But how can I iterate over all keys and values in a NSDictionary, so that I know what keys there are, and what values there are? I know there is something called a for-in-loop in JavaScript. Is there something similar in Objective-C?

推荐答案

code> NSDictionary 支持快速枚举。使用Objective-C 2.0，您可以这样做：

Yes, NSDictionary supports fast enumeration. With Objective-C 2.0, you can do this:

// To print out all key-value pairs in the NSDictionary myDict
for(id key in myDict)
    NSLog(@"key=%@ value=%@", key, [myDict objectForKey:key]);

另一种方法（如果您的目标是Mac OS X 10.5之前的版本，但你仍然可以在10.5和iPhone上使用）是使用 NSEnumerator ：

The alternate method (which you have to use if you're targeting Mac OS X pre-10.5, but you can still use on 10.5 and iPhone) is to use an NSEnumerator:

NSEnumerator *enumerator = [myDict keyEnumerator];
id key;
// extra parens to suppress warning about using = instead of ==
while((key = [enumerator nextObject]))
    NSLog(@"key=%@ value=%@", key, [myDict objectForKey:key]);

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