json - 解析 JSON 时遇到问题

Question

我在 Swift 中解析一些 JSON 时遇到问题。我无法获取返回 nil 的 errors 变量。我想这应该是一本字典吧？下面是从我的 API 返回的 JSON，如控制台中打印的那样。

{
    error = "{\"name\":[\"The name has already been taken.\"],\"email\":[\"The email has already been taken.\"]}";
    success = 0;
}

这是 Swift 代码。

do {
    let json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary

    if let parseJSON = json {
        print(parseJSON)
        let success = parseJSON["success"] as? Int

        if(success == 1) {
            let myAlert = UIAlertController(title: "Alert", message: "Registration successful", preferredStyle: UIAlertControllerStyle.alert);

            let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default){
                (action) in
                self.dismiss(animated: true, completion: nil)
            }

            myAlert.addAction(okAction);
            self.present(myAlert, animated: true, completion: nil)
        } else {
            let errors = parseJSON["error"] as? NSDictionary
            if(errors != nil){
                print("NOT NIL")
                // self.displayAlertMessage()
            }
        }
    }
} catch{
    print(error)
}

编辑这是使用下面 David 的代码打印的 JSON。这是打印到控制台的 parseJSON。

["error": {"name":["The name has already been taken."],"email":["The email has already been taken."]}, "success": 0]

这是我的完整方法，其中包含 Davids 更新的代码。

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

    DispatchQueue.main.async
        {

            //spinningActivity!.hide(true)

            if theError != nil {
                self.displayAlertMessage(theError!.localizedDescription)
                return
            }

            do {
                guard let parseJSON = try JSONSerialization.jsonObject(with: theData!) as? [String:Any] else {return}
                //print(parseJSON)
                let success = parseJSON["success"] as? Int
                if(success == 1) {
                    let myAlert = UIAlertController(title: "Alert", message: "Registration successful", preferredStyle: UIAlertControllerStyle.alert);

                    let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default){
                        (action) in
                        self.dismiss(animated: true, completion: nil)
                    }

                    myAlert.addAction(okAction);
                    self.present(myAlert, animated: true, completion: nil)
                } else {
                    guard let errors = parseJSON["success"] as? Int else {return}
                    print(errors)
                }
            } catch{
                print(error)
            }



    }

}

task.resume()

Answer 1

您的代码存在一些问题，这些问题可能不会直接导致问题，但却是不好的做法。不要在 Swift 中使用 NSDictionary，在解码 JSON 响应时使用 [String:Any] 并且不要使用 .mutableContainers 因为它没有在 Swift 中，可变性由声明变量时的 let 或 var 关键字决定。

此外，请勿将控制台打印包含为 JSON 响应，而应在问题中包含实际的 JSON 响应，因为 Swift 的 print 语句不会生成有效的 JSON。

let apiErrorResponse = """
{
    "error": {
        "name": "The name has already been taken.",
        "email": ["The email has already been taken."]
    },
    "success": 0
}
"""
func handleApiErrorResponse(){
    do {
        guard let parseJSON = try JSONSerialization.jsonObject(with: apiErrorResponse.data(using: .utf8)!) as? [String:Any] else {return}
        let success = parseJSON["success"] as? Int
        if(success == 1) {
            let myAlert = UIAlertController(title: "Alert", message: "Registration successful", preferredStyle: UIAlertControllerStyle.alert);

            let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default){
                (action) in
                self.dismiss(animated: true, completion: nil)
            }

            myAlert.addAction(okAction);
            self.present(myAlert, animated: true, completion: nil)
        } else {
            guard let errors = parseJSON["error"] as? [String:Any] else {return}
            print(errors)
        }
    } catch{
        print(error)
    }
}

handleApiErrorResponse()

输出:

"["name": The name has already been taken., "email": <__NSSingleObjectArrayI 0x608000019f80>(\nThe email has already been taken.\n)\n]\n"