NSFetchRequest fetch properties only

gistfile1.swift

let searchTermPropertyName = "term"
let searchFetchRequest = NSFetchRequest(entityName: SearchEntity.className)
searchFetchRequest.propertiesToFetch = [searchTermPropertyName]
searchFetchRequest.resultType = .DictionaryResultType
let allSearches = try! privateContext.executeFetchRequest(searchFetchRequest) as! [[String: String]]
let allSearchTerms = allSearches.flatMap {$0[searchTermPropertyName]}