我试图根据日期属性过滤核心数据对象.
这是我目前的代码：
func getFetchedResultController(selectedEntity: NSString){
let appDelegate : AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let managedObjectContext: NSManagedObjectContext = appDelegate.managedObjectContext!
let fetchRequest = NSFetchRequest()
let entity = NSEntityDescription.entityForName(selectedEntity as String,inManagedObjectContext: managedObjectContext)
fetchRequest.entity = entity
fetchRequest.fetchBatchSize = 20
let date = NSDate()
let sectionSortDescriptor = NSSortDescriptor(key: "timeStamp < %@",date)
let sortDescriptors = [sectionSortDescriptor] //,secondSortDescriptor]
fetchRequest.sortDescriptors = sortDescriptors
let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest,managedObjectContext: managedObjectContext,sectionNameKeyPath: nil,cacheName: nil)
aFetchedResultsController.delegate = self
self.fetchedResultsController = aFetchedResultsController
var error: NSError? = nil
if !self.fetchedResultsController.performFetch(&error) {
abort()
}
print(fetchedResultsController.fetchedObjects?.count ?? 0)
}
但我得到一个错误：
let sectionSortDescriptor = NSSortDescriptor(key: "timeStamp < %@",date)
我应该如何更改此排序描述符以获取“timeStamp”属性上具有较旧或较新日期的对象？
谢谢.
解决方法
@H_404_17@ 要获取满足某些条件的所有对象,您不需要排序描述符但是谓词,例如：
let predicate = NSPredicate(format: "timeStamp < %@",date) fetchRequest.predicate = predicate
您需要一个排序描述符来按指定的顺序获取对象,
例如：
let sectionSortDescriptor = NSSortDescriptor(key: "timeStamp",ascending: true) let sortDescriptors = [sectionSortDescriptor] fetchRequest.sortDescriptors = sortDescriptors
