SQLFetchedResultsController 介绍
SQLFetchedResultsController 可以让使用 SQLite 建立表格更加容易。对于那些喜欢 SQL
的灵活性，又不想放弃可以轻松建立表格的 Core Data’s NSFetchedResultsController 的开发者，可以试试这个类。
作者注 ：这个脚本正在开发中，还不能保证总是正确的显示列表。
override func viewDidLoad() {
super.viewDidLoad()
var request = SQLFetchRequest()
request.table = "Test as t" //Not tested with > 1 table
request.fields = ["id","title", "(SELECT AVG(id) FROM Test WHERE title=t.title) as idAvg"]
request.predicate = "id % 10 = 0 AND title != 'SomeString'"
request.sortDescriptors = [(key:"title", isASC:true)]
request.groupBy = "title"
request.having = "count(*) > 3"
fetchController = SQLFetchedResultsController(request: request, pathToDatabase: DatabaseSetup.getDatabasePath())
let preview = fetchController!.previewSQL()
println("--SQL Preview: \(preview.SQL) \n--Parameters: \(preview.Parameters)")
}