我正在尝试从中解析数据数据源 http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/ws/RSS/topsongs/limit=30/json，标题已正确解析并显示，但解析图像时出现问题，出现错误：“致命错误：在展开可选值时意外发现 nil”
这是我的代码：
ViewModel.swift
import Foundation
class ViewModel {
let urlString = "http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/ws/RSS/topsongs/limit=30/json"
var titles = [String]()
var images = [String]()
func fetchTitles(success:() -> ()) {
let session = NSURLSession(configuration: NSURLSessionConfiguration.defaultSessionConfiguration())
let url = NSURL(string: urlString)
let task = session.dataTaskWithURL(url!) { (data, response, error) -> Void in
let parser = JSONParser()
self.titles = parser.titlesFromJSON(data!)
success()
}
task.resume()
}
func fetchImages(success:() -> ()) {
let session = NSURLSession(configuration: NSURLSessionConfiguration.defaultSessionConfiguration())
let url = NSURL(string: urlString)
let task = session.dataTaskWithURL(url!) { (data, response, error) -> Void in
let parser = JSONParser()
self.images = parser.imagesFromJSON(data!)
success()
}
task.resume()
}
func numberOfSections() -> Int {
return 1
}
func numberOfItemsInSection(section: Int) -> Int {
return titles.count
}
func titleForItemAtIndexPath(indexPath: NSIndexPath) -> String {
return titles[indexPath.row]
}
}
和 MyTableViewController.swift
import UIKit
class MyTableViewController: UITableViewController {
let viewModel = ViewModel()
var imageCache = [String:UIImage]()
override func viewDidLoad() {
super.viewDidLoad()
self.refresh()
self.refreshControl = UIRefreshControl()
self.refreshControl?.addTarget(self, action: #selector(MyTableViewController.refresh), forControlEvents: .ValueChanged)
}
func refresh() {
viewModel.fetchTitles {
dispatch_async(dispatch_get_main_queue()) {
self.tableView.reloadData()
self.refreshControl?.endRefreshing()
}
}
viewModel.fetchImages {
dispatch_async(dispatch_get_main_queue()) {
self.tableView.reloadData()
self.refreshControl?.endRefreshing()
}
}
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return self.viewModel.numberOfSections()
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.viewModel.numberOfItemsInSection(section)
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! MyTableViewCell
cell.songTitle.text = self.viewModel.titleForItemAtIndexPath(indexPath)
let urlString = self.viewModel.titleForItemAtIndexPath(indexPath)
//found nil
let imgURL: NSURL = NSURL(string: urlString)!
let request: NSURLRequest = NSURLRequest(URL: imgURL)
NSURLConnection.sendAsynchronousRequest(
request, queue: NSOperationQueue.mainQueue(),
completionHandler: {(response: NSURLResponse?, data: NSData?, error: NSError?) -> Void in
if error == nil {
cell.songImage.image = UIImage(data: data!)
}
})
return cell
}
和 JSONParser.swift
import Foundation
class JSONParser {
func titlesFromJSON(data: NSData) -> [String] {
var titles = [String]()
do {
if let json = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? [String: AnyObject],
let feed = json["feed"] as? [String: AnyObject],
entries = feed["entry"] as? [[String: AnyObject]] {
for entry in entries {
if let name = entry["im:name"] as? [String: AnyObject],
label = name["label"] as? String {
titles.append(label)
}
}
}
} catch {
print("error parsing JSON: \(error)")
}
return titles
}
func imagesFromJSON(data: NSData) -> [String] {
var images = [String]()
do {
if let json = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? [String: AnyObject],
let feed = json["feed"] as? [String: AnyObject],
entries = feed["entry"] as? [[String: AnyObject]] {
for entry in entries {
if let name = entry["im:image"]![0] as? [String: AnyObject],
label = name["label"] as? String {
images.append(label)
}
}
}
} catch {
print("error parsing JSON: \(error)")
}
return images
}
}
我有一个 UITableViewCell 的 UiTableViewCell 子类，其中包含 UILabel 和 UIImageView。
我无法弄清楚问题是什么，以及为什么会出现此错误。感谢您的时间。
