我正试图在我在苹果书中学到的这个应用程序中保存表情符号，但问题是我不理解书中的后续步骤，
创建一个静态loadSampleEmojis()方法，该方法将创建并返回预定义的[表情符号]集合。您可以使用EmojiTableViewController中指定给表情符号的列表作为项目列表。
更新emojis以初始化为空集合而不是大样本集合。当调用viewdidload（）方法时，您应该使用loadFromfile（）检查documents / emojis目录中是否有任何以前保存的表情符号对象。如果它们是发现将它们分配给emojis.if没有将emojis分配给loadSampleEmojis（）的结果。
花一点时间考虑一下保存表情符号对象的时机。 在这种情况下，你日期的中心位置是emojis进行Emojitableviewcontroller，意味着每当emojis属性被更改时调用saveToFile（emojis :)是合适的。 接下来，考虑何时可能适合加载存档的表情符号对象。在这个简单的情况下，实际上只需要归档存档数据的一个点：当第一个视图加载时，你应该已经调用了这个方法在第一个视图中控制器viewdidload（）。这是我到现在所写的，
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
}
}
答案 0 :(得分：0)
首先，你需要添加静态方法，它将返回[表情符号]，并包含你的表情符号预设（来自表情符号表视图控制器）。
static func loadSampleEmojis() -> [Emoji]{
return [Your emojis array]}
之后，在表情符号表视图控制器中，您需要定义像
这样的表情符号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，否则指定预设。
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。
此外，您需要更正：
static func loadFromFile() -> [Emoji]? {..}
或者viewDidLoad中的控制流将无效。