等待多个 Alamofire 请求完成

Posted 2023-02-24

【中文标题】等待多个 Alamofire 请求完成

【英文标题】：Wait for multiple Alamofire Requests to finish

【发布时间】：2017-10-15 10:31:41

【问题描述】：

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
            
    

【参考方案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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