问题
I have a code, that parses JSON's list of questions and I can get every property. How can I iterate through the whole file and for each question create an object ?
class ViewController: UIViewController {
var hoge: JSON?
override func viewDidLoad() {
super.viewDidLoad()
let number = arc4random_uniform(1000)
let url = NSURL(string: "http://www.wirehead.ru/try-en.json?\(number)")
var request = NSURLRequest(URL: url!)
var data = NSURLConnection.sendSynchronousRequest(request, returningResponse: nil, error: nil)
if data != nil {
hoge = JSON(data: data!)
let level = hoge!["pack1"][0]["level"].intValue
let questionText = hoge!["pack1"][0]["questionText"].stringValue
let answer1 = hoge!["pack1"][0]["answer1"].stringValue
let answer2 = hoge!["pack1"][0]["answer2"].stringValue
let answer3 = hoge!["pack1"][0]["answer3"].stringValue
let answer4 = hoge!["pack1"][0]["answer4"].stringValue
let correctAnswer = hoge!["pack1"][0]["correctAnswer"].stringValue
let haveAnswered = hoge!["pack1"][0]["haveAnswered"].boolValue
}
}
}
my model of Question which objects I want to create below
class Question {
var level : Int?
var questionText : String?
var answer1 : String?
var answer2 : String?
var answer3 : String?
var answer4 : String?
var correctAnswer : String?
var haveAnswered : Bool = false
init(level: Int, questionText:String, answer1:String, answer2:String, answer3:String, answer4:String, correctAnswer: String, haveAnswered:Bool) {
self.level = level
self.questionText = questionText
self.answer1 = answer1
self.answer2 = answer2
self.answer3 = answer3
self.answer4 = answer4
self.correctAnswer = correctAnswer
self.haveAnswered = false
}
}
回答1:
This is how I would approach the problem.
Step 1
Since your init inside Question does receive non optional objects, I had the feeling that the properties of Questions should be non optional too. I also converted the properties from var to let (tell me if I am wrong).
Step 2
This is the refactored Question class. As you can see I added a class method build that receive a JSON (a SwiftyJSON) and returns a Question (if the json contains correct data), nil otherwise.
Right now I cannot do this with a
failable initializer.
extension String {
func toBool() -> Bool? {
switch self.lowercaseString {
case "true", "1", "yes" : return true
case "false", "0", "no" : return false
default: return nil
}
}
}
class Question {
let level: Int
let questionText: String
let answer1: String
let answer2: String
let answer3: String
let answer4: String
let correctAnswer: String
let haveAnswered: Bool
init(level: Int, questionText:String, answer1:String, answer2:String, answer3:String, answer4:String, correctAnswer: String, haveAnswered:Bool) {
self.level = level
self.questionText = questionText
self.answer1 = answer1
self.answer2 = answer2
self.answer3 = answer3
self.answer4 = answer4
self.correctAnswer = correctAnswer
self.haveAnswered = false
}
class func build(json:JSON) -> Question? {
if let
level = json["level"].string?.toInt(),
questionText = json["questionText"].string,
answer1 = json["answer1"].string,
answer2 = json["answer2"].string,
answer3 = json["answer3"].string,
answer4 = json["answer4"].string,
correctAnswer = json["correctAnswer"].string,
haveAnswered = json["haveAnswered"].string?.toBool() {
return Question(
level: level,
questionText: questionText,
answer1: answer1,
answer2: answer2,
answer3: answer3,
answer4: answer4,
correctAnswer: correctAnswer,
haveAnswered: haveAnswered)
} else {
debugPrintln("bad json \(json)")
return nil
}
}
}
Step 3
Now let's look at viewDidLoad.
func viewDidLoad() {
super.viewDidLoad()
let number = arc4random_uniform(1000)
if let
url = NSURL(string: "http://www.wirehead.ru/try-en.json?\(number)"),
data = NSURLConnection.sendSynchronousRequest(NSURLRequest(URL: url), returningResponse: nil, error: nil) {
// line #a
let rootJSON = JSON(data: data)
// line #b
if let questions = (rootJSON["pack1"].array?.map { return Question.build($0) }) {
// now you have an array of optional questions [Question?]...
}
}
}
At line #a I put inside rootJSON the whole data received from the connection (converted into JSON).
What happen at line #b?
Well I try to access the array located inside "pack1".
rootJSON["pack1"].array?
If the array exists I run the map method. This will extract each cell of the array and I will be able to refer to it with the $0 parameter name inside the closure.
Inside the closure I use this json block (that should represent a question) to build a Question instance.
The result will be an array of Question?. There could be ill values if some son data was not valid. If you want I can show you how to remove the nil values from this array
I could not try the code with real data, hope this helps.
回答2:
Step 1. We will create one protocol with one constructor method in it and Model class
protocol JSONable {
init?(parameter: JSON)
}
class Style: JSONable {
let ID :String!
let name :String!
required init(parameter: JSON) {
ID = parameter["id"].stringValue
name = parameter["name"].stringValue
}
/* JSON response format
{
"status": true,
"message": "",
"data": [
{
"id": 1,
"name": "Style 1"
},
{
"id": 2,
"name": "Style 2"
},
{
"id": 3,
"name": "Style 3"
}
]
}
*/
}
Step 2. We will create extension of JSON which will convert JSON to model class type object
extension JSON {
func to<T>(type: T?) -> Any? {
if let baseObj = type as? JSONable.Type {
if self.type == .array {
var arrObject: [Any] = []
for obj in self.arrayValue {
let object = baseObj.init(parameter: obj)
arrObject.append(object!)
}
return arrObject
} else {
let object = baseObj.init(parameter: self)
return object!
}
}
return nil
}
}
Step 3. Use code with Alamofire or other code.
Alamofire.request(.GET, url).validate().responseJSON { response in
switch response.result {
case .success(let value):
let json = JSON(value)
var styles: [Style] = []
if let styleArr = json["data"].to(type: Style.self) {
styles = styleArr as! [Style]
}
print("styles: \(styles)")
case .failure(let error):
print(error)
}
}
I hope this will be useful.
Please refer to this link for more information on this.
https://github.com/SwiftyJSON/SwiftyJSON/issues/714
回答3:
You can use SwiftyJSONModel which was specifically designed for this purpose. So in your case the model would be like this:
class Question: JSONObjectInitializable {
enum PropertyKey: String {
case level, questionText
case answer1, answer2, answer3, answer4
case correctAnswer, haveAnswered
}
var level : Int?
var questionText : String?
var answer1 : String?
var answer2 : String?
var answer3 : String?
var answer4 : String?
var correctAnswer : String?
var haveAnswered : Bool = false
required init(object: JSONObject<PropertyKey>) throws {
level = object.value(for: .level)
questionText = object.value(for: .questionText)
answer1 = object.value(for: .answer1)
answer2 = object.value(for: .answer2)
answer3 = object.value(for: .answer3)
answer4 = object.value(for: .answer4)
correctAnswer = object.value(for: .correctAnswer)
haveAnswered = object.value(for: .haveAnswered) ?? false
}
}
And then do like this:
let rootJSON = JSON(data: data)
let questions = rootJSON.arrayValue.flatMap { try? Question(json: $0) }
The framework gives you several nice features:
- All the keys are stored in separated enum
PropertyKey - No boilerplate as
stringValue,intValueetc. - If
JSONwill be invalid, framework will give a verbose error and you will immediately see what exactly went wrong
回答4:
for (item, content) in hoge {
let level = content["level"].intValue
}
that should work
来源：https://stackoverflow.com/questions/31661575/how-to-create-objects-from-swiftyjson