转义闭包捕获非转义参数“函数” Xcode 说答案

【问题标题】：Escaping closure captures non-escaping parameter 'function' Xcode says转义闭包捕获非转义参数“函数” Xcode 说
【发布时间】：2021-12-23 14:49:33
【问题描述】：

我正在尝试在两个 API 请求完成后执行 segue，并且我拥有所需的所有数据。我正在尝试这样做，因为请求需要一些时间。但是，当我尝试执行类似 post 的操作时，出现以下错误：

1. Passing a non-escaping function parameter 'anotherFunc' to a call to a non-escaping function parameter can allow re-entrant modification of a variable
2. Escaping closure captures non-escaping parameter 'anotherFunc'
3. Escaping closure captures non-escaping parameter 'function'

我在出现错误的地方添加了 cmets。这是我的代码：

func getUsernameRequest(function: () -> Void) {
            // send an API request to get the userinfo
            let url = "\(K.API.baseAPIEndpoint)/user"
            let headers: HTTPHeaders = [...]
            AF.request(url, headers: headers).responseDecodable(of: UserModel.self) { response in // this is where the #3 error shows up
                if let value = response.value {
                    self.username = value.username
                    // and do other things
                    function()
                } else {
                    offlineBanner()
                }
            }
        }
        
        func getMessagesRequest(function: (()->Void)->Void, anotherFunc:()->Void) {
            let postDetailUrl = "\(K.API.baseAPIEndpoint)/posts/\(postArray[indexPath.row].id)"
            let headers: HTTPHeaders = [...]
            // send an API request to get all the associated messages
            AF.request(postDetailUrl, headers: headers).responseDecodable(of: PostDetailModel.self) { response in // this is the #2 error shows up
               if let value = response.value {
                   self.messages = value.messages
                   function(anotherFunc) // this is where the #1 error shows up
               } else {
                   offlineBanner()
               }
            }
        }
        
        func performSegueToChat() -> Void {
            self.performSegue(withIdentifier: K.Segue.GotoChat, sender: self)
        }
        
        getMessagesRequest(function: getUsernameRequest, anotherFunc: performSegueToChat)

提前谢谢你。

【问题讨论】：

标签： ios swift alamofire

【解决方案1】：

我用下面的代码做了这个，它按我的预期工作！（但它们不太干净）

        func getUsernameRequest(function: @escaping() -> Void) {
            // send an API request to get the username
            let url = "\(K.API.baseAPIEndpoint)/user"
            AF.request(url, headers: headers).responseDecodable(of: GetUsernameModel.self) { response in
                    if let value = response.value {
                        self.username = value.username
                        function()
                    } else {
                        offlineBanner()
                    }
                }
        }
        
        func getMessagesRequest(function: @escaping(@escaping()->Void)->Void, anotherFunc: @escaping()->Void) {
            let postDetailUrl = "\(K.API.baseAPIEndpoint)/posts/\(postArray[indexPath.row].id)"
            // send an API request to get all the associated messages and put them into messages array
            AF.request(postDetailUrl, headers: headers).responseDecodable(of: PostDetailModel.self) { response in
                if let value = response.value {
                    self.messages = value.messages
                    function(anotherFunc)
                } else {
                    offlineBanner()
                }
            }
        }
        
        func performSegueToChat() -> Void {
            self.performSegue(withIdentifier: K.Segue.GotoChat, sender: self)
        }
        
        getMessagesRequest(function: getUsernameRequest, anotherFunc: performSegueToChat)

【讨论】：