Question

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.

Please also tell me about valueForKey method (I was unable to get that from doc).

Answer 1

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.

If you want the index of the item, as your title suggests, use indexOfObject:, it also invokes isEqual: to locate the match.

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.