我有一个使用UICollectionView的应用程序,当用户点击并保持单元格时,它允许用户转移并重新排列该单元格的位置(类似于iOS允许您在您的主屏幕上重新排序应用程序)。使用Swift自动重新排列核心数据中的UICollectionView
当然,订单的更改并未保存,当您离开视图并返回时,它会返回到原来的顺序。我觉得有一种方法可以在UITableView中自动保存单元格的新顺序,而无需在Core Data中明确写出所有内容。
我该如何在UICollectionView中做到这一点?或者这是不可能的,我将不得不手动将所有内容写入Core Data?
编辑:当前相关代码:
@IBOutlet weak var groupCollection: UICollectionView!
var longPressGesture : UILongPressGestureRecognizer?
var newGroupOrderNum : Int?
let indexPath : IndexPath = []
var aryGroup : NSMutableArray!
func handleLongGesture(gesture: UILongPressGestureRecognizer) {
switch(gesture.state) {
case UIGestureRecognizerState.began:
guard let selectedIndexPath = self.groupCollection.indexPathForItem(at: gesture.location(in: self.groupCollection)) else {
break
}
groupCollection.beginInteractiveMovementForItem(at: selectedIndexPath)
case UIGestureRecognizerState.changed:
groupCollection.updateInteractiveMovementTargetPosition(gesture.location(in: gesture.view!))
case UIGestureRecognizerState.ended:
groupCollection.endInteractiveMovement()
var timestamp: Date {
return Date()
}
let creationTime = timestamp
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let entity = NSEntityDescription.entity(forEntityName: "Group", in:managedContext)
let group = NSManagedObject(entity: entity!, insertInto: managedContext)
let orderChangeGroup = aryGroup.object(at: indexPath.row)
group.setValue(orderChangeGroup, forKey: "groupOrderNum")
do {
try managedContext.save()
}
catch let error as NSError {
print("Could not save \(error), \(error.userInfo)")
}
group.setValue(creationTime, forKey: "creationTime")
default:
groupCollection.cancelInteractiveMovement()
}
}
也许'NSFetchedResultsController'是你所追求的。它会给你所有更新/插入/删除任何NSManagedObjectContext细粒度的通知? –