保存UITableViewCells的顺序 [英] Save order of UITableViewCells

问题描述

我在tableview中添加了选项来对单元格进行排序/重新排序。我使用了本教程： http://www.ioscreator.com/教程/重新排序，排表 - 视图 - iOS8上，迅速。现在我想问一下如何保存细胞的分类/顺序？我还使用Core Data和 fetchedResultsController 。

I added the option in my tableview to sort/reorder cells. I used this tutorial: http://www.ioscreator.com/tutorials/reordering-rows-table-view-ios8-swift. Now I'd like to ask how I can save the sorting/order of the cells? I also use Core Data and the fetchedResultsController.

推荐答案

添加一个额外的属性到用于存储排序顺序的Core Data模型对象。例如，您可以拥有 orderIndex 属性：

Add an extra attribute to your Core Data model object that is used to store the sort order. For example, you could have an orderIndex attribute:

class MyItem: NSManagedObject {

    @NSManaged var myOtherAttribute: String
    @NSManaged var orderIndex: Int32

}

然后，在您的获​​取结果控制器的获取请求的排序描述符中使用此属性：

Then, use this attribute in your sort descriptor for your fetched results controller's fetch request:

fetchRequest.sortDescriptors = [NSSortDescriptor(key: "orderIndex", ascending: true)]

最后，更新UITableViewDataSource方法中的 orderIndex 属性：

And finally, update the orderIndex property in your UITableViewDataSource method:

func tableView(tableView: UITableView, moveRowAtIndexPath sourceIndexPath: NSIndexPath, toIndexPath destinationIndexPath: NSIndexPath) {

    if var items = fetchedResultsController.fetchedObjects as? [MyItem],
        let itemToMove = fetchedResultsController.objectAtIndexPath(sourceIndexPath) as? MyItem {

            items.removeAtIndex(sourceIndexPath.row)
            items.insert(itemToMove, atIndex: destinationIndexPath.row)

            for (index, item) in enumerate(items) {
                item.orderIndex = Int32(index)
            }
    }
}

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