Question

我实现了一个表视图，它显示了一个文档列表

我使用此代码实现了重新排序功能

var documents = [PDFDocument]()
override func tableView(_ tableView: UITableView, moveRowAt sourceIndexPath: IndexPath, to destinationIndexPath: IndexPath) {

    let movedObject = self.documents[sourceIndexPath.row]

    let fileManager = FileManager.default

    documents.remove(at: sourceIndexPath.row)

    documents.insert(movedObject, at: destinationIndexPath.row)

    NSLog("%@", "\(sourceIndexPath.row) => \(destinationIndexPath.row) \(documents)")



    do {


        let document = documents[sourceIndexPath.row]
        let documentURL = document.documentURL?.absoluteString


        let document_Dest = documents[destinationIndexPath.row]
        let documentURL_Dest = document_Dest.documentURL?.absoluteString

        try fileManager.moveItem(atPath: documentURL!, toPath: documentURL_Dest!)
    }
    catch let error as NSError {
        print("Ooops! Something went wrong: \(error)")
    }




    // To check for correctness enable: self.tableView.reloadData()
   refreshData()

}


  private func refreshData() {
    let fileManager = FileManager.default
    let documentDirectory = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]
    let contents = try! fileManager.contentsOfDirectory(at: documentDirectory, includingPropertiesForKeys: nil, options: .skipsHiddenFiles)
    documents = contents.flatMap { PDFDocument(url: $0) }

    tableView.reloadData()
}

它在重新排序时完全正常，但问题是当我关闭应用程序并再次启动它时（任何时候刷新数据函数运行），行返回到它们的默认位置。虽然我需要保存重新排序的更改。

Answer 1

tableView中的重新排序仅适用于tableView。此重新排序不会影响原始数据源。关闭应用程序并再次运行后，重新加载数据的方法将从文档目录中获取原始数据。当tableView中此顺序发生变化时，您需要更改此原始文件的顺序。

从文档目录中获取数据。

private func refreshData() 
{
    let fileManager = FileManager.default
    let documentDirectory = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]
    let contents = try! fileManager.contentsOfDirectory(at: documentDirectory, includingPropertiesForKeys: nil, options: .skipsHiddenFiles)
    documents = contents.flatMap { PDFDocument(url: $0) }
}

创建一个字典，其中key为文档目录文件或文件夹名称，值为索引。

private func refreshData() 
{
    let fileManager = FileManager.default
    let documentDirectory = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]
    let contents = try! fileManager.contentsOfDirectory(at: documentDirectory, includingPropertiesForKeys: nil, options: .skipsHiddenFiles)
    documents = contents.flatMap { PDFDocument(url: $0) 


    let index = 0
    let documentDic = NSMutableDictionary()
    for element in documents
    {
         documentDic.setValue(index, forKey: element.documentURL?.absoluteString) 
         index = index + 1
    }  

}

将其保存在用户默认值

中

private func refreshData() 
{
    let fileManager = FileManager.default
    let documentDirectory = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]
    let contents = try! fileManager.contentsOfDirectory(at: documentDirectory, includingPropertiesForKeys: nil, options: .skipsHiddenFiles)
    documents = contents.flatMap { PDFDocument(url: $0) 

    let index = 0
    let documentDic = NSMutableDictionary()
    for element in documents
    {
         documentDic.setValue(index, forKey: element.documentURL?.absoluteString) 
         index = index + 1
    }  


    NSUserDefaults.standardUserDefaults().setObject(documentDic, forKey: "ReorderingFormat")
}

用户重新排序后，更改与每个网址对应的字典中的值。

//Read data from User Defaults
let dic = NSUserDefaults.standardUserDefaults().objectForKey("Reordering Format")
for element in documents
{
    //This way you get the order or index number for any directory.
    dic.objectForKey(element)
}

当用户再次进入应用程序时，根据存储在nsuserdefaults中的字典值管理您的数组。

在数据刷新后，TableView中的行重新排序将重置为默认值

1 个答案: