Question

我正在尝试解码JSON。我用于解码JSON的快捷功能是：

func GetChapInfo(){

    let endpoint = "https://chapel-logs.herokuapp.com/chapel"

    let endpointUrl = URL(string: endpoint)

    do {
        var request = URLRequest(url: endpointUrl!)
        request.httpMethod = "GET"
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
        request.addValue("application/json", forHTTPHeaderField: "Accept")

        let task = URLSession.shared.dataTask(with: request){
            (data: Data?, response: URLResponse?, error: Error?) in


            let dataAsString = String(data: data!, encoding: .utf8)
            //print(dataAsString)

            if(error != nil) {
                print("Error")
            }
            else{
                do{
                    guard let chapData = try? JSONDecoder().decode(Chapel.self, from: data!) else {
                        print("Error: Couldn't decode data into chapData")
                        return
                    }
                    for E in chapData.chap {
                        print(E.Day as Any)
                    }
                }
        }
        }

        task.resume()
    }
}

我在Swift中的struct是

struct Chapel: Decodable {
    let chap: [Chap]
}

struct Chap: Decodable {
    let Name: String?
    let Loc: String?
    let Year: Int?
    let Month: Int?
    let Day: Int?
    let Hour: Int?
    let Min: Int?
    let Sec: Int?
}

服务器发出的响应是：

{"chap":{"Name":"Why Chapel","Loc":"FEC","Year":2018,"Month":9,"Day":4,"Hour":16,"Min":1,"Sec":7}}

但是，当我运行此程序时，程序会打印出“错误：无法将数据解码为chapData”，我无法弄清原因。

Answer 1

首先 catch 解码错误。永远不要try?。捕获的错误更具描述性

打算解码Array<Any>，但找到了字典

方法：键chap的值是一个字典，而不是数组

struct Chapel: Decodable {
    let chap: Chap
}

然后您必须打印

print(chapData.chap.Day)

您可以减少代码。不需要显式的URLRequest和默认GET请求的标头。足够了：

let endpoint = "https://chapel-logs.herokuapp.com/chapel"
let endpointUrl = URL(string: endpoint)!

do {

    let task = URLSession.shared.dataTask(with: endpointUrl) { (data, response, error) in
    ...

Swift 4 JSON解码

1 个答案: