问题描述
是否有可能在NSArray中找出数组中是否存在给定值（不使用for循环搜索）？任何默认的随机方法。我浏览了文档，但没有找到太多相关性。
Is it possible in an NSArray to find out if a given value exists or not in the array (without searching it using a for loop)? Any default random method. I went through the documentation, but didn't find much relevant.
还请告诉我 valueForKey 方法（我无法从doc获取）。
Please also tell me about valueForKey method (I was unable to get that from doc).
推荐答案
containsObject：方法通常会给你你所要求的 - 而它的名称听起来像是在查询特定的实例（即两个具有相同语义值的对象不匹配）它实际上调用 isEqual：关于对象，所以它通过值进行测试。
The containsObject: method will usually give you what you're asking - while its name sounds like you are querying for a specific instance (i.e. two object with the same semantic value would not match) it actually invokes isEqual: on the objects so it is testing by value.
如果你想要项目的索引，正如你的标题所暗示的那样，使用 indexOfObject：，它还会调用 isEqual：来查找匹配项。
If you want the index of the item, as your title suggests, use indexOfObject:, it also invokes isEqual: to locate the match.
valueForKey：适用于拥有一系列词典的情况;它在每个字典中查找键并返回结果和数组。
valueForKey: is for when you have an array of dictionaries; it looks up the key in each dictionary and returns and array of the results.
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