如何快速完成将参数传递给函数

问题描述

我是 swift 的新手，想知道如何在函数完成时将参数传递给函数.我尝试只传入一个变量 String ，但这不起作用.这是我用于处理 api 请求的类.这是我需要将内容传递到的地方，以便它可以将其添加到搜索字段并返回结果.

I'm new to swift and am wondering how I can pass arguments into a function when that function has a completion. I tried just passing in a variable String but that did not work. Here is my class for handling an api request. This is where i need to pass the contents to so that it can add it to a search field and return the results.

public class API {

    func apiRequest(search: String, completion: @escaping (Result) -> ()) {

        //URL
        var query = search.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)
        let url = URL(string: "https://calorieninjas.p.rapidapi.com/v1/nutrition?query=" + query!)

        //URL REQUEST
        var request = URLRequest(url: url!, cachePolicy: .useProtocolCachePolicy, timeoutInterval: 10.0)

        //Specify header
        let headers = [
            "x-rapidapi-key": "3be44a36b7msh4d4738910c1ca4dp1c2825jsn96bcc44c2b19",
            "x-rapidapi-host": "calorieninjas.p.rapidapi.com"
        ]

        request.httpMethod="GET"
        request.allHTTPHeaderFields = headers

        //Get the URLSession
        let session = URLSession.shared

        //Create data task
        let dataTask = session.dataTask(with: request) { (data, response, error) in

            let result = try? JSONDecoder().decode(Result.self, from: data!)
            print(result)
            DispatchQueue.main.async {
                completion(result!)
            }


        }

        //Fire off data task
        dataTask.resume()

    }
}

这是我的内容视图代码，我试图将文本框的内容传递到此函数中，以便我可以从 api 获取结果:

This is my content view code where I am trying to pass in the contents of a text box into this function so that i can get the result back from the api:

struct ContentView: View {

    @State var result = Result()
    @State private var searchItem: String = ""

    var body: some View {
        ZStack(alignment: .top) {
            Rectangle()
                .fill(Color.myPurple)
                .ignoresSafeArea(.all)
            VStack {
                TextField("Enter food", text: $searchItem)
                    .background(Color.white)
                    .padding()
                    .textFieldStyle(RoundedBorderTextFieldStyle())

                SearchButton()
                    .padding(.top)
                    .onTapGesture {
                        API().apiRequest { (result) in //IDEALLY I WOULD LIKE TO PASS IN THE CONTENTS OF THE TEXT BOX HERE INTO apiRequest
                            self.result = result
                        }
                    }

            }
        }
    }
}

我确信解决方案很简单，我只是不习惯语法和诸如此类的语法，但非常感谢对此的任何帮助.

I'm sure the solution is simple I am just not used to the syntax and such of swift quite yet any help with this is much appreciated.

推荐答案

你的函数 'apiRequest' 有 2 个参数:

Your function 'apiRequest' has 2 parameters:

1. 搜索:字符串(此参数需要一个字符串)
2. 完成:@escaping (Result) ->()

所以当你调用这个方法时，你也会传递这两个参数，就像这样:

So when you call this method, you will pass these 2 parameters as well, like this:

.onTapGesture {
    API().apiRequest(search: "String you want to pass", completion: { (result) in
        self.result = result
    })
 }

了解闭包，因为此完成参数也是一种闭包(转义闭包).

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