To Save SMALL data - NSUserDefaults, NSCoding as suggested by other people or saving in plist also or else create a file in document directory and write the contents of array in that file.
LARGE Data- Save it in database using either sqlite or core data.
Choice depends on the requirement of the application and since you have not given the details of the data like maximum number of strings in the array, everyone can suggest you instead of telling a solution. Hope it helps :)