使用 Alamofire 的同步请求

Posted 2023-02-24

【中文标题】使用 Alamofire 的同步请求

【英文标题】：Synchronous request using Alamofire

【发布时间】：2018-08-17 16:45:59

【问题描述】：

我检查了其他解决方案，例如 How to make a synchronous request using Alamofire?，我按照所有说明进行操作，但我无法完成请求并使用这些信息。

我需要从谷歌地图中检索距离和路线点，然后使用该信息完成一个数组。 这是函数：

func getGoogleMapsInfo(startLocation: CLLocationCoordinate2D, restaurant: Customer, completion: @escaping (_ distance: Int, _ routePoints: String)  -> ())

    let endLocation = CLLocationCoordinate2D(latitude: restaurant.latitude, longitude: restaurant.longitude)
    let origin = "\(startLocation.latitude),\(startLocation.longitude)"
    let destination = "\(endLocation.latitude),\(endLocation.longitude)"
    var distance = 0
    var routePoints = ""

    let url = "https://maps.googleapis.com/maps/api/directions/json?origin=\(origin)&destination=\(destination)&mode=walking"
    Alamofire.request(url).responseJSON  response in

        switch response.result 
        case .success:

            do 
                self.json = try JSON(data: response.data!)

                distance = Int(truncating: self.json["routes"][0]["legs"][0]["distance"]["value"].numberValue)


                let route = self.json["routes"].arrayValue.first
                let routeOverviewPolyline = route!["overview_polyline"].dictionary
                routePoints = (routeOverviewPolyline?["points"]?.stringValue)!
                completion(distance, routePoints)
                break
             catch 
                print("error JSON")
            


        case .failure(let error):
            print(error)
            completion(distance, routePoints)
            break
        

    

这就是我所说的：

    for index in 0...nearbyRestaurants.count - 1 

        getGoogleMapsInfo(startLocation: currentLocation, restaurant: nearbyRestaurants[index])  (distance, routePoints) in
            nearbyRestaurants[index].distance = distance
            nearbyRestaurants[index].routePoints = routePoints
        

     

如果有人可以帮助我，我将不胜感激。

【问题讨论】：

"检查了其他解决方案，例如如何使用 Alamofire 发出同步请求？"不要检查它们。永远永远永远永远不会同步网络。绝不。我有没有提到过？

@matt 同步网络请求可以来自后台线程。

@Cristik 我有没有提到“除非你已经在后台线程上”？

@matt 我可能在某处看到过 :)

【参考方案1】：

不要尝试使异步请求同步

改为使用DispatchGroup,notify 在所有网络请求完成后调用。

let group = DispatchGroup()
for index in 0..<nearbyRestaurants.count 
    group.enter()
    getGoogleMapsInfo(startLocation: currentLocation, restaurant: nearbyRestaurants[index])  (distance, routePoints) in
        nearbyRestaurants[index].distance = distance
        nearbyRestaurants[index].routePoints = routePoints
        group.leave()
    

group.notify(queue: DispatchQueue.main) 
        print("all info data has been received")