我试着在这个应用程序中保存我在苹果书里学到的表情符号，但问题是我不理解书中接下来的步骤，
创建一个静态loadSampleEmojis()方法，该方法将创建并返回预定义的[Emoji]集合。您可以使用EmojiTableViewController中分配给emojis的列表作为项目列表。
更新要初始化为空集合而不是大样本集合的emojis。调用viewdidload（）方法时，应使用loadFromfile（）检查documents/emojis目录中以前保存的任何Emoji对象。如果找到它们，请将它们分配给emojis。如果没有将emojis分配给loadSampleEmojis（）的结果。
花点时间想想什么时候可以保存你的Emoji对象。
在这种情况下，日期的中心点是emojis在Emojitableviewcontroller上执行，这意味着只要emojis属性发生更改，就可以调用saveToFile（emojis:）。
接下来，考虑何时可以加载存档的Emoji对象。同样，在这种简单的情况下，只需要一点存档数据就不需要归档：第一个视图加载时。您应该已经在第一个视图控制器viewdidload（）中调用此方法。
这是我到现在为止写的，
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
}
}
最佳答案
首先，您需要添加静态方法，它将返回[Emoji]，并包含您的Emoji预置（来自Emoji表视图控制器）。
static func loadSampleEmojis() -> [Emoji]{
return [Your emojis array]}
之后，在Emoji Table View Controller中，需要定义如下的emojis
var emojis = [Emoji]()
接下来，在viedDidLoad（）中，您需要检查您的ArchiveURL中是否有任何数据？如果是-将其分配给你的表情符号，否则分配预设。
if let savedEmojis = Emoji.loadFromFile() {
emojis = savedEmojis
} else {
emojis = Emoji.loadSampleEmoji()}
在那之后加上
Emoji.saveToFile(emoji: emojis)
到tableView（u，moveRowAt:，to:）、tableView（editingStyle）和unwindSegue。
此外，您还需要纠正：
static func loadFromFile() -> [Emoji]? {..}
或者viewDidLoad中的控制流不起作用。