使用 Swift 3
当我单击 MainController.swift 中的按钮 followButtonClick 时，发生错误导致崩溃。 blogID 结果为零，但是当我打印 mainArray 时，所有对象都在那里，所以我的代码中有一些问题无法修复。 blogID 未正确访问。
fatal error: unexpectedly found nil while unwrapping an Optional value
我没有使用 NSCoder 和 UserDefaults 来保存 mainArray 和 followedArray 的整个数组，而是保存后面的 blogsID 然后显示我们通过抓取已保存 ID 的对象来保存这些对象。
MainController.swift
var mainArray = [Blog]()
var followedArray = [Blog]()
var filteredArray = [Blog]()
var followedIdentifiers = Set<String>()
// viewDidLoad
override func viewDidLoad() {
super.viewDidLoad()
retrieveDataFromServer()
loadUserDefaults()
}
// Title for Header
func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
if !(searchController.isActive && searchController.searchBar.text != "") {
if section == 0 {
return "Followed Blogs"
}
else {
return "All Blogs"
}
}
return "Filtered Blogs"
}
// Number of Rows in Section
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if !(searchController.isActive && searchController.searchBar.text != "") {
if section == 0 {
return followedArray.count
}
else if (section == 1) {
return mainArray.count
}
}
return filteredArray.count
}
// CellForRowAt indexPath
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let CellIdentifier = "Cell"
var cell = tableView.dequeueReusableCell(withIdentifier: CellIdentifier) as! CustomCell
if cell != cell {
cell = CustomCell(style: UITableViewCellStyle.default, reuseIdentifier: CellIdentifier)
}
// Configuring the cell
var blogObject: Blog
if !(searchController.isActive && searchController.searchBar.text != "") {
if indexPath.section == 0 {
blogObject = followedArray[indexPath.row]
cell.populateCell(blogObject, isFollowed: true, indexPath: indexPath, parentView: self)
}
else if indexPath.section == 1 {
blogObject = mainArray[indexPath.row]
cell.populateCell(blogObject, isFollowed: false, indexPath: indexPath, parentView: self)
}
}
else {
blogObject = filteredArray[indexPath.row]
cell.populateCell(blogObject, isFollowed: false, indexPath: indexPath, parentView: self)
}
return cell
}
// Follow Button
@IBAction func followButtonClick(_ sender: UIButton!) {
// Adding row to tag
let buttonPosition = (sender as AnyObject).convert(CGPoint.zero, to: self.myTableView)
if let indexPath = self.myTableView.indexPathForRow(at: buttonPosition) {
// Showing Status Labels
let cell = self.myTableView.cellForRow(at: indexPath) as! CustomCell
cell.firstStatusLabel.isHidden = false
cell.secondStatusLabel.isHidden = false
// Change Follow to Following
(sender as UIButton).setImage(UIImage(named: "follow.png")!, for: .normal)
cell.followButton.isHidden = true
cell.followedButton.isHidden = false
// Checking wether to import from mainArray or filteredArray to followedArray
if !(searchController.isActive && searchController.searchBar.text != "") {
self.myTableView.beginUpdates()
// -*- Error breaks here -*-
// Save identifier into followedIdentifier array
self.followedIdentifiers.insert(mainArray[indexPath.row].blogID)
// ----- Inserting Cell to followedArray -----
followedArray.insert(mainArray[indexPath.row], at: 0)
myTableView.insertRows(at: [IndexPath(row: 0, section: 0)], with: .fade)
// ----- Removing Cell from mainArray -----
mainArray.remove(at: indexPath.row)
let rowToRemove = indexPath.row
self.myTableView.deleteRows(at: [IndexPath(row: rowToRemove, section: 1)], with: .fade)
self.myTableView.endUpdates()
myTableView.reloadData()
// After Updating Table, Save the Archived to UserDefaults
saveUserDefaults()
}
else {
self.myTableView.beginUpdates()
// Remove identifier into followedIdentifier array
self.followedIdentifiers.remove(followedArray[indexPath.row].blogID)
// ----- Inserting Cell to followedArray -----
let blogObject: Blog = filteredArray[indexPath.row]
let indexOfObjectInArray = mainArray.index(of: blogObject)
followedArray.insert(blogObject, at: 0)
// ----- Removing Cell from filteredArray -----
filteredArray.remove(at: indexPath.row)
mainArray.remove(at: indexOfObjectInArray!)
let rowToRemove = indexPath.row
self.myTableView.deleteRows(at: [IndexPath(row: rowToRemove, section: 0)], with: .fade)
self.myTableView.endUpdates()
myTableView.reloadData()
// After Updating Table, Save the Archived to UserDefaults
saveUserDefaults()
}
}
}
// Unfollow Button
@IBAction func followedButtonClick(_ sender: UIButton!) {
// Adding row to tag
let buttonPosition = (sender as AnyObject).convert(CGPoint.zero, to: self.myTableView)
if let indexPath = self.myTableView.indexPathForRow(at: buttonPosition) {
// Hiding Status Labels
let cell = self.myTableView.cellForRow(at: indexPath) as! CustomCell
cell.firstStatusLabel.isHidden = true
cell.secondStatusLabel.isHidden = true
// Change Following to Follow
(sender as UIButton).setImage(UIImage(named: "followed.png")!, for: .normal)
cell.followButton.isHidden = false
cell.followedButton.isHidden = true
self.myTableView.beginUpdates()
// Remove identifier into followedIdentifier array
self.followedIdentifiers.remove(followedArray[indexPath.row].blogID)
// ----- Inserting Cell to mainArray -----
mainArray.insert(followedArray[indexPath.row], at: 0)
myTableView.insertRows(at: [IndexPath(row: 0, section: 1)], with: .fade)
// ----- Removing Cell from followedArray -----
followedArray.remove(at: indexPath.row)
let rowToRemove = indexPath.row
self.myTableView.deleteRows(at: [IndexPath(row: rowToRemove, section: 0)], with: .fade)
self.myTableView.endUpdates()
myTableView.reloadData()
// After Updating Table, Save the Archived to UserDefaults
saveUserDefaults()
}
}
// Saving UserDefaults
func saveUserDefaults() {
let key = "followedID"
UserDefaults.standard.setValue(self.followedIdentifiers, forKey: key)
UserDefaults.standard.synchronize()
}
// Load UserDefaults
func loadUserDefaults() {
let key = "followedID"
UserDefaults.standard.setValue(Array(self.followedIdentifiers), forKey: key)
self.followedIdentifiers = Set(UserDefaults.standard.stringArray(forKey: key)!)
}
// Retrieving Data from Server
func retrieveDataFromServer() {
let getDataURL = "http://example.com/receiving.php"
let url: NSURL = NSURL(string: getDataURL)!
do {
let data: Data = try Data(contentsOf: url as URL)
let jsonArray = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as! NSMutableArray
// Clear the arrays
self.followedArray = [Blog]()
self.mainArray = [Blog()]
// Looping through jsonArray
for jsonObject in jsonArray {
if let blog = Blog.createBlog(from: jsonObject as AnyObject) {
// Check if identifiers match
if followedIdentifiers.contains(blog.blogID) {
self.followedArray.append(blog)
} else {
self.mainArray.append(blog)
}
}
}
} catch {
print("Error: (Retrieving Data)")
}
myTableView.reloadData()
}
Blog.swift - 处理博客对象
import UIKit
class Blog: NSObject, NSCoding {
var blogName: String!
var blogStatus1: String!
var blogStatus2: String!
var blogURL: String!
var blogID: String!
var blogType: String!
var blogDate: String!
var blogPop: String!
static func createBlog(from jsonObject: AnyObject) -> Blog? {
guard let bID: String = jsonObject.object(forKey: "id") as? String,
let bName: String = jsonObject.object(forKey: "blogName") as? String,
let bStatus1: String = jsonObject.object(forKey: "blogStatus1") as? String,
let bStatus2: String = jsonObject.object(forKey: "blogStatus2") as? String,
let bURL: String = jsonObject.object(forKey: "blogURL") as? String,
let bType: String = jsonObject.object(forKey: "blogType") as? String,
let bDate: String = jsonObject.object(forKey: "blogDate") as? String,
let bPop: String = jsonObject.object(forKey: "blogPop") as? String
else {
print("Error: (Creating Blog Object)")
return nil
}
let blog = Blog()
blog.blogName = bName
blog.blogStatus1 = bStatus1
blog.blogStatus2 = bStatus2
blog.blogURL = bURL
blog.blogID = bID
blog.blogType = bType
blog.blogDate = bDate
blog.blogPop = bPop
return blog
}
convenience required init?(coder aDecoder: NSCoder) {
self.init ()
self.blogName = aDecoder.decodeObject(forKey: "blogName") as! String
self.blogStatus1 = aDecoder.decodeObject(forKey: "blogStatus1") as! String
self.blogStatus2 = aDecoder.decodeObject(forKey: "blogStatus2") as! String
self.blogURL = aDecoder.decodeObject(forKey: "blogURL") as! String
self.blogID = aDecoder.decodeObject(forKey: "blogID") as! String
self.blogType = aDecoder.decodeObject(forKey: "blogType") as! String
self.blogDate = aDecoder.decodeObject(forKey: "blogDate") as! String
self.blogPop = aDecoder.decodeObject(forKey: "blogPop") as! String
}
func encode(with aCoder: NSCoder) {
aCoder.encode(blogName, forKey: "blogName")
aCoder.encode(blogStatus1, forKey: "blogStatus1")
aCoder.encode(blogStatus2, forKey: "blogStatus2")
aCoder.encode(blogURL, forKey: "blogURL")
aCoder.encode(blogID, forKey: "blogID")
aCoder.encode(blogType, forKey: "blogType")
aCoder.encode(blogDate, forKey: "blogDate")
aCoder.encode(blogPop, forKey: "blogPop")
}
}
最佳答案
您面临的直接问题是您有一个隐式解包的可选 blogID尚未分配值。造成这种情况的根本原因是您使用隐式展开的选项掩盖了它，因为它没有透露您无法初始化 Blog 的位置。实例正确。
而不是使用静态函数来创建 Blog从 JSON 字典来看，您应该使用可失败的初始化程序。这将允许您在适当的情况下使用非可选属性，并在对象未正确初始化时给您一个编译器或运行时错误。
import Foundation
class Blog: NSObject, NSCoding {
var blogName: String
var blogStatus1: String
var blogStatus2: String
var blogURL: String // Note this should probably be a URL rather than a String
var blogID: String
var blogType: String
var blogDate: String // Note this should probably be a Date rather than a String
var blogPop: String
private init (name: String,status1: String,status2: String,url: String,id: String,type: String,date: String,pop: String) {
blogName = name
blogStatus1 = status1
blogStatus2 = status2
blogURL = url
blogID = id
blogType = type
blogDate = date
blogPop = pop
super.init()
}
convenience init?(jsonObject: [String:Any]) {
guard let bID = jsonObject["id"] as? String,
let bName = jsonObject["blogName"] as? String,
let bStatus1 = jsonObject["blogStatus1"] as? String,
let bStatus2 = jsonObject["blogStatus2"] as? String,
let bURL = jsonObject["blogURL"] as? String,
let bType = jsonObject["blogType"] as? String,
let bDate = jsonObject["blogDate"] as? String,
let bPop = jsonObject["blogPop"] as? String
else {
print("Error: (Creating Blog Object)")
return nil
}
self.init(name: bName, status1: bStatus1, status2: bStatus2, url: bURL, id: bID, type: bType, date: bDate, pop: bPop)
}
convenience required init?(coder aDecoder: NSCoder) {
guard let blogName = aDecoder.decodeObject(forKey: "blogName") as? String,
let blogStatus1 = aDecoder.decodeObject(forKey: "blogStatus1") as? String,
let blogStatus2 = aDecoder.decodeObject(forKey: "blogStatus2") as? String,
let blogURL = aDecoder.decodeObject(forKey: "blogURL") as? String,
let blogID = aDecoder.decodeObject(forKey: "blogID") as? String,
let blogType = aDecoder.decodeObject(forKey: "blogType") as? String,
let blogDate = aDecoder.decodeObject(forKey: "blogDate") as? String,
let blogPop = aDecoder.decodeObject(forKey: "blogPop") as? String else {
print("Error: (Creating Blog Object)")
return nil
}
self.init(name: blogName, status1: blogStatus1, status2: blogStatus2, url: blogURL, id: blogID, type: blogType, date: blogDate, pop: blogPop)
}
func encode(with aCoder: NSCoder) {
aCoder.encode(blogName, forKey: "blogName")
aCoder.encode(blogStatus1, forKey: "blogStatus1")
aCoder.encode(blogStatus2, forKey: "blogStatus2")
aCoder.encode(blogURL, forKey: "blogURL")
aCoder.encode(blogID, forKey: "blogID")
aCoder.encode(blogType, forKey: "blogType")
aCoder.encode(blogDate, forKey: "blogDate")
aCoder.encode(blogPop, forKey: "blogPop")
}
}
请注意，这可能不会立即解决显示 ID 的问题，但它将帮助您找到未初始化 Blog 的位置。正确实例
关于ios - Swift:无法正确访问 JSON 代码。 (打开包装时发现为零)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44709952/