ios - 将对象从 URLSession 传递到 ViewController

Question

我正在尝试将我创建的名为 detail 的对象从名为 RestManager.swift 的 swift 文件传递​​到 ViewController。该对象包含所有元素，但是当我在我的 View Controller 中调用它时，它是空的。从我在网上收集到的信息来看，它可能与在后台线程上工作的 URLSession 有关

我的 RestManager.swift 看起来像这样。

class RestManager {


func reqDetails(id: Int) {
    // Create URL
    let id = String(id)
    let url = "https://website.example.com/"
    let url = URL(string: url + id)!

    let task = URLSession.shared.dataTask(with: url) { (data, response, error) in

        if error != nil
        {
            print ("ERROR")
        }

        else
        {
            if let content = data
            {

                    let jsonData = JSON(data: content)

                    let id = jsonData["id"].intValue
                    let name = jsonData["title"]["rendered"].string!
                    let link = jsonData["link"].url!
                    let content = jsonData["content"]["rendered"].string!


                    // Create Object
                    let detail = Detail(id: id, name: name, content: content, thumbnailUrl: link)
                    self.details.append(detail)

            }
        }
    }
    task.resume()
}
}

我的 View Controller 看起来像这样:

class DetailViewController: UIViewController {

var ListingID = Int()
let restManager = RestManager()

@IBOutlet weak var ContentLabel: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()
    restManager.reqDetails(id: ListingID)
    ContentLabel.text? = restManager.details[0].name // After running the app this index value is out of range.


}

..

}

Answer 1

像这样在函数中使用closer来传递数据

'

func reqDetails(id: Int,completionHandler:@escaping (_ detilObject:Detail)->Void) {
    // Create URL
    let id = String(id)
    let url = "https://website.example.com/"
    let url = URL(string: url + id)!

    let task = URLSession.shared.dataTask(with: url) { (data, response, error) in

        if error != nil
        {
            print ("ERROR")
        }

        else
        {
            if let content = data
            {

                    let jsonData = JSON(data: content)

                    let id = jsonData["id"].intValue
                    let name = jsonData["title"]["rendered"].string!
                    let link = jsonData["link"].url!
                    let content = jsonData["content"]["rendered"].string!


                    // Create Object
                    let detail = Detail(id: id, name: name, content: content, thumbnailUrl: link)
                    self.details.append(detail)
                    completionHandler(self.details)

            }
        }
    }
    task.resume()
}

'

然后像这样调用你的函数。'

restManager.reqDetails(id: ListingID , completionHandler: { (detail) in
                // here is your detail object
            })

'