在 swift4 中使用文件管理器保存
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【中文标题】在 swift4 中使用文件管理器保存【英文标题】：save with file manager in swift4 【发布时间】：2017-12-27 14:04:25 【问题描述】：我正在尝试将我在苹果书中学到的表情符号保存在这个应用程序中，但问题是我不明白书中的后续步骤，
创建一个静态loadSampleEmojis() 方法，该方法将创建并返回一个预定义的[Emoji] 集合。您可以使用分配给EmojiTableViewController 中表情符号的列表作为您的项目列表。
更新表情符号以初始化为空集合而不是大型样本集合。当调用 viewdidload() 方法时，您应该使用 loadFromfile() 检查文档/表情符号目录中是否有任何先前保存的表情符号对象。如果它们是发现将它们分配给 emojis。如果没有将 emojis 分配给 loadSampleEmojis() 的结果。
花点时间考虑一下何时适合保存您的表情符号对象。 在这种情况下，日期的中心点是表情符号在 Emojitableviewcontroller 上进行，这意味着只要 emojis 属性发生更改，就可以调用 saveToFile(emojis:)。 接下来，考虑何时加载存档的表情符号对象可能合适。再次，在这个简单的情况下，实际上只有一个点需要取消存档存档数据：当第一个视图加载时。你应该已经在调用这个方法在第一个视图控制器 viewdidload() 中。
这是我写到现在的，
import Foundation
struct Emoji : Codable
var symbol : String
var name : String
var description : String
var usage : String
static let documentsdirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
static let archiveurl = documentsdirectory.appendingPathComponent("emojis").appendingPathExtension("plist")
static func SaveToFile (emojis: [Emoji])
let propetyencod = PropertyListEncoder()
let encodemoj = try? propetyencod.encode(emojis)
try? encodemoj?.write(to : archiveurl , options : .noFileProtection)
static func loadeFromFile () -> [Emoji]
let propetydicod = PropertyListDecoder()
if let retrivdate = try? Data(contentsOf: archiveurl),
let decodemoj = try?
propetydicod.decode(Array<Emoji>.self, from: retrivdate)
return decodemoj
return [Emoji]()
import UIKit
class emojiTableViewController: UITableViewController
var emojis : [Emoji] = [
Emoji(symbol: "????", name: "Grinning Face",
description: "A typical smiley face.", usage: "happiness"),
Emoji(symbol: "????", name: "Confused Face",
description: "A confused, puzzled face.", usage: "unsure what to think; displeasure"),
Emoji(symbol: "????", name: "Heart Eyes",
description: "A smiley face with hearts for eyes.",
usage: "love of something; attractive"),
Emoji(symbol: "????", name: "Police Officer",
description: "A police officer wearing a blue cap with a gold badge.", usage: "person of authority"),
Emoji(symbol: "????", name: "Turtle", description:
"A cute turtle.", usage: "Something slow"),
Emoji(symbol: "????", name: "Elephant", description:
"A gray elephant.", usage: "good memory"),
Emoji(symbol: "????", name: "Spaghetti",
description: "A plate of spaghetti.", usage: "spaghetti"),
Emoji(symbol: "????", name: "Die", description: "A single die.", usage: "taking a risk, chance; game"),
Emoji(symbol: "⛺️", name: "Tent", description: "A small tent.", usage: "camping"),
Emoji(symbol: "????", name: "Stack of Books",
description: "Three colored books stacked on each other.",
usage: "homework, studying"),
Emoji(symbol: "????", name: "Broken Heart",
description: "A red, broken heart.", usage: "extreme sadness"), Emoji(symbol: "????", name: "Snore",
description:
"Three blue \'z\'s.", usage: "tired, sleepiness"),
Emoji(symbol: "????", name: "Checkered Flag",
description: "A black-and-white checkered flag.", usage:
"completion")]
override func viewDidLoad()
super.viewDidLoad()
navigationItem.leftBarButtonItem = editButtonItem
tableView.rowHeight = UITableViewAutomaticDimension
tableView.estimatedRowHeight = 52.0
// Uncomment the following line to preserve selection between presentations
// self.clearsSelectionOnViewWillAppear = false
// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
// self.navigationItem.rightBarButtonItem = self.editButtonItem()
override func didReceiveMemoryWarning()
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
// MARK: - Table view data source
override func numberOfSections(in tableView: UITableView) -> Int
// #warning Incomplete implementation, return the number of sections
return 1
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
// #warning Incomplete implementation, return the number of rows
if section == 0
return emojis.count
else
return 0
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
let cell = tableView.dequeueReusableCell(withIdentifier: "emojicell", for: indexPath) as! cellviewTableViewCell
let emoji = emojis[indexPath.row]
cell.update(with: emoji)
cell.showsReorderControl = true
return cell
@IBAction func editbutton(_ sender: UIBarButtonItem)
let tablevieweditingmod = tableView.isEditing
tableView.setEditing(!tablevieweditingmod, animated: true)
override func tableView(_ tableView: UITableView, editingStyleForRowAt indexPath: IndexPath) -> UITableViewCellEditingStyle
return.delete
override func viewWillAppear(_ animated: Bool)
tableView.reloadData()
/*
// Override to support conditional editing of the table view.
override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool
// Return false if you do not want the specified item to be editable.
return true
*/
// Override to support editing the table view.
override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath)
if editingStyle == .delete
// Delete the row from the data source
emojis.remove(at: indexPath.row)
tableView.deleteRows(at: [indexPath], with: .automatic)
else if editingStyle == .insert
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
// Override to support rearranging the table view.
override func tableView(_ tableView: UITableView, moveRowAt fromIndexPath: IndexPath, to: IndexPath)
let movedEmoji = emojis.remove(at: fromIndexPath.row)
emojis.insert(movedEmoji, at: to.row)
tableView.reloadData()
/*
// Override to support conditional rearranging of the table view.
override func tableView(_ tableView: UITableView, canMoveRowAt indexPath: IndexPath) -> Bool
// Return false if you do not want the item to be re-orderable.
return true
*/
/*
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
*/
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
if segue.identifier == "editcell"
let indexpath = tableView.indexPathForSelectedRow!
let emoji = emojis[indexpath.row]
let edittableview = segue.destination as! addTableViewController
edittableview.emoji = emoji
@IBAction func unwindToemojitableview(segue: UIStoryboardSegue )
guard segue.identifier == "saveun" else return
let sourseviewcontroler = segue.source as! addTableViewController
if let emoji = sourseviewcontroler.emoji
if let selectedindexpath = tableView.indexPathForSelectedRow
emojis[selectedindexpath.row] = emoji
tableView.reloadRows(at: [selectedindexpath], with: .none)
else
let newindexpath = IndexPath(row: emojis.count, section: 0)
emojis.append(emoji)
tableView.insertRows(at: [newindexpath], with: .automatic)
import UIKit
class addTableViewController: UITableViewController
var emoji : Emoji?
@IBOutlet weak var symboltexfiel: UITextField!
@IBOutlet weak var nametexfiel: UITextField!
@IBOutlet weak var descriptexfiel: UITextField!
@IBOutlet weak var usagetexfiel: UITextField!
@IBOutlet weak var savebutt: UIBarButtonItem!
override func viewDidLoad()
super.viewDidLoad()
if let emoji = emoji
symboltexfiel.text = emoji.symbol
nametexfiel.text = emoji.name
descriptexfiel.text = emoji.description
usagetexfiel.text = emoji.usage
ubdatesavebutt()
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
super.prepare(for: segue, sender: sender)
guard segue.identifier == "saveun" else return
let sym = symboltexfiel.text ?? ""
let nam = nametexfiel.text ?? ""
let de = descriptexfiel.text ?? ""
let use = usagetexfiel.text ?? ""
emoji = Emoji(symbol: sym, name: nam, description: de, usage: use)
func ubdatesavebutt ()
let symbol = symboltexfiel.text ?? ""
let name = nametexfiel.text ?? ""
let descr = descriptexfiel.text ?? ""
let use = usagetexfiel.text ?? ""
savebutt.isEnabled = !symbol.isEmpty && !name.isEmpty && !descr.isEmpty && !use.isEmpty
@IBAction func ediittex(_ sender: UITextField)
ubdatesavebutt()
import UIKit
class cellviewTableViewCell: UITableViewCell
@IBOutlet weak var symbollabel: UILabel!
@IBOutlet weak var namelabel: UILabel!
@IBOutlet weak var descriptionlabel: UILabel!
override func awakeFromNib()
super.awakeFromNib()
// Initialization code
override func setSelected(_ selected: Bool, animated: Bool)
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
func update(with emoji : Emoji)
symbollabel.text = emoji.symbol
namelabel.text = emoji.name
descriptionlabel.text = emoji.description
【问题讨论】：
只在您的问题中添加 相关 代码 - 不要只是粘贴到整个文件中。这是对其他用户的不尊重。 【参考方案1】：首先，您需要添加静态方法，该方法将返回 [Emoji]，并包含您的表情符号预设（来自表情符号表视图控制器）。
static func loadSampleEmojis() -> [Emoji]
return [Your emojis array]
之后，在 Emoji Table View Controller 中，您需要定义类似
的表情符号var emojis = [Emoji]()
接下来，在 viedDidLoad() 中，您需要检查 ArchiveURL 中是否有任何数据？如果是 - 将其分配给您的表情符号，否则分配预设。
if let savedEmojis = Emoji.loadFromFile()
emojis = savedEmojis
else
emojis = Emoji.loadSampleEmoji()
然后添加
Emoji.saveToFile(emoji: emojis)
到 tableView(_,moveRowAt:,to:)、tableView(editingStyle) 和 unwindSegue。
另外，你需要更正：
static func loadFromFile() -> [Emoji]? ..
否则 viewDidLoad 中的控制流将不起作用。
【讨论】：
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