Swift Alamofire 异步问题

Posted 2023-02-24

【中文标题】Swift Alamofire 异步问题

【英文标题】：Swift Alamofire Async Issue

【发布时间】：2021-06-10 04:41:19

【问题描述】：

这里是 swift 的新手。

我正在尝试在另一个 AF.request 调用中进行 AF.request 调用，一切正常。

问题是fetchAllUsers() 在所有内容加载完毕后被调用。因此，我必须刷新页面才能让fetchAllUsers() 执行，而不是立即获取所有用户。

我认为使用闭包可以避免这个问题，但它仍在发生。

我做错了吗？

func fetchAllUsers(completionHandler: @escaping ([User]) -> Void) 
        let allUsersUrl = baseUrl + "users/"
        let headers: HTTPHeaders = [
            .authorization(bearerToken: NetworkManager.authToken)
        ]
        
        if let url = URL(string: allUsersUrl) 
            AF.request(url, headers: headers).responseDecodable(of: [User].self)  response in
                if let users = response.value 
                    completionHandler(users)
                 else 
                    print("Users is empty")
                
            
         else 
            print("URL error")
        
    

 func login(param: [String:String], completionHandler: @escaping (Int) -> Void) 
    let loginUrl = baseUrl + "auth/login"        
    
    // Sets the Logged In User
    AF.request(loginUrl, method: .post, parameters: param, encoding: JSONEncoding.default, headers: nil).responseString  response in
        if let data = response.data 
            let authTokenString = String(decoding: data, as:UTF8.self).components(separatedBy: " ")
            
            // Sets the authentication token
            NetworkManager.authToken = authTokenString[1]
            
            self.fetchAllUsers  users in
                for user in users 
                    if param["username"] == user.username 
                        HomeViewModel.loggedInUser = user
                    
                
            
                            
            completionHandler(response.response!.statusCode)
        
    

【参考方案1】：

将主函数的完成处理程序和状态码传递给 fetchAllUsers 并在它自己的完成处理程序之后调用它

completionHandler(response.response!.statusCode) 在 self.fetchAllUsers 关闭 之前执行，因为它正在等待 api 响应完成。 completionHandler(response.response!.statusCode) 正在销毁 self.fetchAllUsers 闭包 在执行之前，所以我在 self.fetchAllUsers 中调用了 completionHandler(response.response!.statusCode)关闭后

 completionHandler(users)
 mainCompletion(statusCode)  

完整的代码如下

func fetchAllUsers(statusCode:Int, mainCompletion: @escaping (Int) -> Void, completionHandler: @escaping ([User]) -> Void) 
        let allUsersUrl = baseUrl + "users/"
        let headers: HTTPHeaders = [
            .authorization(bearerToken: NetworkManager.authToken)
        ]
    
        if let url = URL(string: allUsersUrl) 
            AF.request(url, headers: headers).responseDecodable(of: [User].self)  response in
                if let users = response.value 
                    completionHandler(users)
                    mainCompletion(statusCode)
                 else 
                        print("Users is empty")
                
            
         else 
            print("URL error")
        
    

func login(param: [String:String], completionHandler: @escaping (Int) -> Void) 
    let loginUrl = baseUrl + "auth/login"        

    // Sets the Logged In User
    AF.request(loginUrl, method: .post, parameters: param, encoding: JSONEncoding.default, headers: nil).responseString  response in
        if let data = response.data 
            let authTokenString = String(decoding: data, as:UTF8.self).components(separatedBy: " ")
        
            // Sets the authentication token
            NetworkManager.authToken = authTokenString[1]
        
            self.fetchAllUsers(statusCode: response.response!.statusCode, mainCompletion: completionHandler)  users in
                for user in users 
                    if param["username"] == user.username 
                        HomeViewModel.loggedInUser = user
                    
                
            
                        
            
        
    

【讨论】：

您好，所以代码按我想要的方式工作。谢谢你。您能否简要解释一下为什么这是有效的以及为什么我之前的无效？

当然，更新的答案和解释请让我知道如果还有问题@sameTbh