我有一个问题,我正在尝试解决与完成处理程序的使用有关的问题。我的 iOS 程序有 3 层:ViewController->Service->Networking。我需要通过 View Controller 的 API 调用加载一些数据。
我在 ViewController 中定义了函数(completionHandlers),这些函数应该在数据请求完成后执行,并且在只有两层存在时实现完成处理程序时很舒服,但在以下情况下会感到困惑:
DashboardViewController.swift
import UIKit
@IBDesignable class DashboardViewController: UIViewController {
@IBOutlet weak var stepCountController: ExpandedCardView!
var articles:[Article]?
let requestHandler = RequestHandler()
let dashboardService = DashboardService()
override func viewDidLoad() {
super.viewDidLoad()
dashboardService.getDashboardData(completionHandler: getDashboardDataCompletionHandler)
}
func getDashboardDataCompletionHandler(withData: DashboardDataRequest) {
print(withData)
}
}
DashboardService.swift
import Foundation
class DashboardService: GeneralService {
var requestHandler: DashboardRequestHandler
override init() {
requestHandler = DashboardRequestHandler()
super.init()
}
//this function should execute requestHandler.requestDashboardData(), and then execute convertDashboardData() with the result of previous get request
func getDashboardData(completionHandler: @escaping (DashboardDataRequest) -> Void) {
//on network call return
guard let url = URL(string: apiResourceList?.value(forKey: "GetDashboard") as! String) else { return }
requestHandler.requestDashboardData(url: url, completionHandler: convertDashboardData(completionHandler: completionHandler))
}
func convertDashboardData(completionHandler: (DashboardDataRequest) -> Void) {
//convert object to format acceptable by view
}
}
DashboardRequestHandler.swift
import Foundation
class DashboardRequestHandler: RequestHandler {
var dataTask: URLSessionDataTask?
func requestDashboardData(url: URL, completionHandler: @escaping (DashboardDataRequest) -> Void) {
dataTask?.cancel()
defaultSession.dataTask(with: url, completionHandler: {(data, response, error) in
if error != nil {
print(error!.localizedDescription)
}
guard let data = data else {
return
}
do {
let decodedJson = try JSONDecoder().decode(DashboardDataRequest.self, from: data)
completionHandler(decodedJson)
} catch let jsonError {
print(jsonError)
}
}).resume()
}
}
如果你看看 DashboardService.swift 中的评论,我的问题就很明显了。我将一个完成处理程序从 ViewController 传递到 Service,并且 Service 有自己的完成处理程序,该处理程序会传递给 RequestHandler,其中 View Controller 完成处理程序 (getDashboardDataCompletionHandler) 应在 Service 完成处理程序 (convertDashboardData()) 之后执行
请帮助我澄清如何实现这一点。我尝试像这样链接完成处理程序是否犯了设计错误,或者我是否遗漏了一些明显的东西。
谢谢
--编辑-- 我的请求处理程序实现如下:
import Foundation
class RequestHandler {
// let defaultSession = URLSession(configuration: .default)
var defaultSession: URLSession!
init() {
guard let path = Bundle.main.path(forResource: "Api", ofType: "plist") else {
print("Api.plist not found")
return
}
let apiResourceList = NSDictionary(contentsOfFile: path)
let config = URLSessionConfiguration.default
if let authToken = apiResourceList?.value(forKey: "AuthToken") {
config.httpAdditionalHeaders = ["Authorization": authToken]
}
defaultSession = URLSession(configuration: config)
}
}
最佳答案
在这种情况下使用委托(delegate)会更清晰,例如这样:
protocol DashboardServiceDelegate {
func didLoaded(_ viewModel: DashboardViewModel)
}
class DashboardViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
dashboardService.delegate = self
dashboardService.getDashboardData()
}
}
extension DashboardViewController: DashboardServiceDelegate {
func didLoaded(_ viewModel: DashboardViewModel) {
///
}
}
protocol DashboardRequestHandlerDelegate() {
func didLoaded(request: DashboardDataRequest)
}
class DashboardService: GeneralService {
private lazy var requestHandler: DashboardRequestHandler = { reqHandler in
reqHandler.delegate = self
return reqHandler
}(DashboardRequestHandler())
func getDashboardData() {
guard let url = ...
requestHandler.requestDashboardData(url: url)
}
}
extension DashboardService: DashboardRequestHandlerDelegate {
func didLoaded(request: DashboardDataRequest) {
let viewModel = convert(request)
delegate.didLoaded(viewModel)
}
}
关于ios - swift 4 中的完成处理程序,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/49230041/