使用数组根对象在 Swift 中解析 JSON 数组

Posted 2023-03-15

【中文标题】使用数组根对象在 Swift 中解析 JSON 数组

【英文标题】：Parsing JSON array in Swift with array root object

【发布时间】：2020-10-26 18:50:28

【问题描述】：

我正在尝试使用以下格式解析 json 数组：

 ["id":1,"date":1596827226.558827,"at":"@mrpit", "name":"Pitmen", "content":"This is the first post, There is a bunch of interesting information in here",
"id":2,"date":1596827234.901298, "at":"@mrben", "name":"Benman", "content":"This is the second post, pretend there is a bunch of scientific information in here.",
"id":3,"date":1596827268.411034, "at":"@mrgreen", "name":"The Green Machine", "content":"This is the thrid post, idk what you wanna pretend is here, maybe something political",
"id":4,"date":1596834988.94011, "at":"@mrman", "name":"The Man who Can", "content":"And finally we are at the forth post, there is tons going on here, maybe even something offensive."] 

我很麻烦，因为根对象似乎是一个数组。

我试图使用类似的东西

struct DataSet: Decodable 
    let post: [SinglePost]


struct SinglePost: Decodable
    let id: Int
    let date: Double
    let at: String
    let name: String
    let content: String



 static func getPost(returnWith: @escaping (DataSet?, Bool)->()) 
        
        let session = URLSession.shared
        let decoder = JSONDecoder()
        let uString = serverUrl
        
        if let url = URL(string: serverUrl + "/post/") 
            let task = session.dataTask(with: url, completionHandler:  data1, response, error in
                if (error != nil) 
                    returnWith(nil, false)
                    return
                
                
                if let dataString = String(data: data1!, encoding: .utf8) 
                    print(dataString)
                    
                    do 
                        
                        let postSet = try decoder.decode(DataSet.self, from: Data(dataString.utf8))
                        returnWith(postSet, true)
                        
                    
                        
                    catch let jsonError 
                        print("Error Serializing JSON", jsonError)
                        returnWith(nil, false)
                    
                 else 
                  returnWith(nil, false)
                
                
            )
            
            task.resume()
            
        
    

但这不起作用。

这样做的最佳方法是什么。抱歉，我对 swift 很陌生，所以这可能有一个明显的答案。

【参考方案1】：

问题在于您试图解码字典而不是数组。

只是改变

let postSet = try decoder.decode(DataSet.self, from: Data(dataString.utf8))

到

let postSet = try decoder.decode([SinglePost].self, from: Data(dataString.utf8))

编辑/更新：

关于您的方法签名，只需将其更改为返回数组而不是 DataSet 结构，我将返回错误而不是 Bool：

static func getPost(completion: @escaping ([SinglePost]?, Error?) -> ()) 
    let session = URLSession.shared
    let decoder = JSONDecoder()
    if let url = URL(string: serverUrl + "/post/") 
        let task = session.dataTask(with: url)  data, response, error in
            guard let data = data else 
                completion(nil, error)
                return
            
            do 
                completion(try decoder.decode([SinglePost].self, from: data), nil)
             catch 
                print("Error Decoding JSON", error)
                completion(nil, error)
            
        
        task.resume()
    

用法：

getPost  posts, error in
    guard let posts = posts else 
        print(error ?? "")
    
    for post in posts 
        print(post)
    

【讨论】：

那返回类型会改成什么？

只需将方法签名更改为static func getPost(returnWith: @escaping ([SinglePost]?, Bool)->()) 顺便说一句，我会将completionHandler 名称从returnWith 更改为刚刚完成

非常感谢！

我试过了，但当时还不够长，哈哈