How to limit the result count of NSFetchRequest?

I want to have a feature of "Recent 20 Items" in my iOS app. I us开发者_StackOverflow中文版e Core Data and NSFetchRequest. How can I limit the result number to 20 to achieve this? Thank you in advance!

Kai.

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set the fetchLimit of the NSFetchRequest

[request setFetchLimit:20];

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Swift 3.0 uses:

request.fetchLimit = 20