json - 如何从 JSON 和核心数据下载图像以在 Swift 中的 tableView 中显示

Question

在这里，我正在下载 JSON 数据并将其保存在核心数据中以供离线存储。在 tableView 中显示 JSON 数据时，它对我来说很好。但是，当我从核心数据中获取 JSON 数据时，我得到了文本，但无法在 tableView 中显示图像，为什么？任何人都可以在下面的代码中帮助我吗

import UIKit
import CoreData

struct JsonData {

var nameS: String?
var picS: String?
var spouseS: String?

init(name: String, image: String, spouse: String) {

    self.nameS = name
    self.picS = image
    self.spouseS = spouse
}
}

class ViewController: UIViewController {

@IBOutlet weak var tableView: UITableView!

let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

var iteamsArray = [JsonData]()

override func viewDidLoad() {

    fetchData()
}

func downloadJsonwithImages() {

    let urlStr = "http://microblogging.wingnity.com/JSONParsingTutorial/jsonActors"
    let url = URL(string: urlStr)
    URLSession.shared.dataTask(with: url!, completionHandler: {(data, response, error) in

        guard let respData = data else {
            return
        }
        guard error == nil else {
            print("error")
            return
        }
        do{
            let jsonObj = try JSONSerialization.jsonObject(with: respData, options: .allowFragments) as! [String: Any]

            let actors = jsonObj["actors"] as! [[String: Any]]

            for actor in actors {

                let name = actor["name"] as! String
                let pic = actor["image"] as! String
                let spouse = actor["spouse"] as! String

                self.iteamsArray.append(JsonData(name: name, image: pic, spouse: spouse))
            }
            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        }
        catch {
            print("catch error")
        }
    }).resume()

    self.saveCoreData()
}

func saveCoreData(){

    let urlStr = "http://microblogging.wingnity.com/JSONParsingTutorial/jsonActors"
    let url = URL(string: urlStr)
    URLSession.shared.dataTask(with: url!, completionHandler: {(data, response, error) in

        guard let respData = data else {
            return
        }
        guard error == nil else {
            print("error")
            return
        }
        do{
            let jsonObj = try JSONSerialization.jsonObject(with: respData, options: .allowFragments) as! [String: Any]

            let actors = jsonObj["actors"] as! [[String: Any]]
            for actor in actors {

                let name = actor["name"] as! String
                let pic = actor["image"] as! String
                let spouse = actor["spouse"] as! String

                let coreData = NSEntityDescription.insertNewObject(forEntityName: "Actor", into: self.context) as! Actor
                coreData.name = name
                coreData.spouse = spouse

                //Converting NSString to NSData
                let picNSData = pic.data(using: String.Encoding(rawValue: String.Encoding.utf8.rawValue))!
                //assigning NSData value to core data attribute
                coreData.image = picNSData as NSData
                print("core data saved images \(coreData.image!)")
            }
            try self.context.save()
        }
        catch {
            print("catch error")
        }
    }).resume()
}


func fetchData() {

    do {
        let fetchRequest : NSFetchRequest<Actor> = Actor.fetchRequest()
        let actors = try context.fetch(fetchRequest)

        if actors.count > 0 {

            for actor in actors as [Actor] {

                let nameCore = actor.value(forKey: "name")
                let spouseCore = actor.value(forKey: "spouse")

                //here imageData contains nsdata
                let imageData = actor.value(forKey: "image")

                //converting NSData to String for append JsonData Struct
                let imageCore = String(describing: imageData)
                print("we r in fetch image.. \(imageCore)")

                self.iteamsArray.append(JsonData(name: nameCore as! String, image: imageCore , spouse: spouseCore as! String))
            }
            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        }
        else {
            downloadJsonwithImages()
        }
    } catch { print(error) }
}


func loadImageFrom(URL url:String, forImage imageView:UIImageView) {
    DispatchQueue.global(qos: .userInteractive).async {

        //when i run second time means its fetching from core data cell.picImageview.image != nil
        let data = NSData(contentsOf: URL(string: url)!)//fatal error: unexpectedly found nil while unwrapping an Optional value
        DispatchQueue.main.sync {
            imageView.image = UIImage(data: data! as Data)
        }
    }
}

}

// MARK: - TableView

extension ViewController: UITableViewDataSource, UITableViewDelegate {

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return iteamsArray.count
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let cell = tableView.dequeueReusableCell(withIdentifier: "JsonCell", for: indexPath) as! JsonTableViewCell
    let aData = iteamsArray[indexPath.row]

    cell.labelName.text = aData.nameS
    cell.labelUsername.text = aData.spouseS


    if cell.picImageview.image == nil {

        self.loadImageFrom(URL: aData.picS!, forImage: cell.picImageview)
    }else {
        //what should i do to fetch from core data
        self.loadImageFrom(URL: aData.picS!, forImage: cell.picImageview)
    }

    cell.selectionStyle = .none
    return cell
}
}

请帮我从核心数据中获取图像到表格视图。

标签： jsonswiftcore-datauiimage