等待多个 Alamofire 请求完成

Question

我的网络类中有一个下面的函数，它执行 Alamofire 请求过程。我在我的模型类中调用这个函数，当 Alamofire 完成请求时，它调用通知模型类的委托函数。我的问题是我多次调用这个 Alamofire 函数，并且两者都应该在通知模型类之前完成。现在我用非常愚蠢的方式处理它。正如我搜索的那样，可以使用 DispatchGroup 但我无法弄清楚，如何实现它。谢谢。

模型类

 @objc func refresh_fiks(){
    let network = Network()
    network.delegate = self
    self.teams = [[]]
    network.getRequest(req: 1)
    network.getRequest(req: 2)

}

请求函数：

    func response(){
    print(response_json.count)
    if(response_json.count == path){
        self.delegate?.sendJson(response_json)
    }
    }
    func getRequest(req: Int) {
    path = req
    let rot = Router(method: .get, path: req, parameters: nil)
    Alamofire.request(rot)
        .response { response in
            print(response.request?.url! as Any)
            // check for errors
            guard response.error == nil else {
                // got an error in getting the data, need to handle it
                print(response.error!)
                let errorJson: JSON = [ "Error" : "Can't get the data!"]
                self.response_json.append(errorJson)
                self.response()
                return
            }
            // make sure we got some JSON since that's what we expect
            guard (response.data?.base64EncodedString()) != nil else {
                print("Error: \(String(describing: response.error))")
                let errorJson: JSON = [ "Error" : "Can't get the data!"]
                self.response_json.append(errorJson)
                self.response()
                return
            }
            guard response.response?.statusCode == 200 else{
                let errorJson: JSON = [ "Error" : "Can't get the data!"]
                self.response_json.append(errorJson)
                self.response()
                return
            }
            let json = JSON(data: response.data!)
            // get and print the title
            if json != nil{
                self.response_json.append(json)
                self.response()
            } else {
                let errorJson: JSON = [ "Error" : "Can't get the data!"]
                self.response_json.append(errorJson)
                self.response()
                return
            }
    }
}

Answer 1

我对您的代码做了一些更改：

网络类：

func response(array: [JSON]){
    print(array.count)
    if(array.count == path){
        self.delegate?.sendJson(array)
    }
}

func getMultipleRequests(_ requests: [Int]) {
    DispatchQueue.global(qos: .background).async {
        let group = DispatchGroup()

        var array: [JSON] = []

        for request in requests {

            group.enter()

            self.getRequest(req: request, completion: { (json) in
                array.append(json)
                group.leave()
            })
        }

        group.wait()
        //this line below won't be called until all entries will leave the group
        self.response(array: array)
    }
}

func getRequest(req: Int, completion: @escaping (_ json: JSON) -> Void) {
    path = req
    let rot = Router(method: .get, path: req, parameters: nil)
    Alamofire.request(rot)
        .response { response in
            print(response.request?.url! as Any)
            // check for errors
            guard response.error == nil else {
                // got an error in getting the data, need to handle it
                print(response.error!)
                let errorJson: JSON = [ "Error" : "Can't get the data!"]
                completion(errorJson)
                return
            }
            // make sure we got some JSON since that's what we expect
            guard (response.data?.base64EncodedString()) != nil else {
                print("Error: \(String(describing: response.error))")
                let errorJson: JSON = [ "Error" : "Can't get the data!"]
                completion(errorJson)
                return
            }
            guard response.response?.statusCode == 200 else{
                let errorJson: JSON = [ "Error" : "Can't get the data!"]
                completion(errorJson)
                return
            }
            let json = JSON(data: response.data!)
            // get and print the title
            if json != nil{
                completion(json)
            } else {
                let errorJson: JSON = [ "Error" : "Can't get the data!"]
                completion(errorJson)
                return
            }
    }
}

所以 getRequest 函数现在有一个完成块，它将从每个请求中返回一个 json 结果，而 getMultipleRequests 函数将接收来自任何人的一堆请求 p>

这是你如何使用它

你的类，调用 refresh_fiks：

@objc func refresh_fiks(){
    let network = Network()
    network.delegate = self
    self.teams = [[]]

    network.getMultipleRequests([1,2])
}

此外，您可能需要使用 group.notify 而不是使用 group.wait()，最好通知所有条目在指定队列中离开组，像 main:

group.notify(queue: DispatchQueue.main, execute: {
   print("All Done") 
   self.response(array: array)
}) 

关于 DispatchGroups 的阅读内容：

RayWenderlich

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