[英]Swift 4 JSON decoding
我正在嘗試解碼JSON。 我用於解碼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?
}
我從服務器得到的響應是:
{"chap":{"Name":"Why Chapel","Loc":"FEC","Year":2018,"Month":9,"Day":4,"Hour":16,"Min":1,"Sec":7}}
但是,當我運行此程序時,程序將打印出“錯誤:無法將數據解碼為chapData”,我無法弄清楚原因。
首先catch
解碼錯誤。 從不try?
。 捕獲的錯誤更具描述性
預期對
Array<Any>
進行解碼,但找到了字典
裝置:用於鍵的值chap
是一個字典,不是數組
struct Chapel: Decodable {
let chap: Chap
}
然后你必須打印
print(chapData.chap.Day)
您可以減少代碼。 不需要顯式的URLRequest
和默認GET請求的標頭。 這足夠了:
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
...
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