Store XML data as an array, Swift - arrays

Question

So I am working on a project which will allow users to do multiple different quizzes.
My XML, which is hosted online, is of the following format:
<questions>
<question>
<clue> sample clue 1 </clue>
<correct_answer>2</correct_answer>
<enumeration>1</enumeration>
<info> sample info 1 </info>
<location_clue>Sample locationClue (5,5)</location_clue>
<option_a>Ans1</option_a>
<option_b>Ans2</option_b>
<option_c>Ans3</option_c>
</question>
<question>
<clue> sample clue 2 </clue>
<correct_answer>3</correct_answer>
<enumeration>2</enumeration>
<info> sample info 2 </info>
<location_clue>Sample locationClue (4,2)</location_clue>
<option_a>Ans1</option_a>
<option_b>Ans2</option_b>
<option_c>Ans3</option_c>
</question>
</questions>
my parser initiation looks like this:
if let urlString = URL(string: "realURL goes here.xml -- This has an actual url in my code obviously.")
{
if let parser = XMLParser(contentsOf: urlString)
{
parser.delegate = self
parser.parse()
}
}
parserDidStartElement:
func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String] = [:])
{
thisName = elementName
if thisName == "hunt"
{
}
}
ParserFoundCharacter:
func parser(_ parser: XMLParser, foundCharacters string: String)
{
let data = string.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
if data.count != 0
{
switch thisName
{
case "clue": questionClue = data
break
case "info": questionInfo = data
break
case "location_clue": locationClue = data
break
case "option_a": questionAnswerA = data
break
case "option_b": questionAnswerB = data
break
case "option_c": questionAnswerC = data
default:
break
}
}
}
This is the HuntDetail.swift class which creates a scruct named QUIZ, inside of this scruct there are currently 4 variables, question, answerA, answerB and answerC:
import Foundation
struct QUIZ {
var question = ""
var answerA = ""
var answerB = ""
var answerC = ""
}
Essentially the app will allow users to take multi-choice quizzes. When answers are selected a progress bar at the top of the interface will indicate their progress through the current quiz.
I was wondering if it would be possible to store the value of: clue,info,location_clue,option_a,b,c... inside of an array, from the array I will start to formulate the actual quiz functionality.
As it stands right now, the application will only display the last element of the data previously mentioned.
I know this is long and probably hard to understand what I'm trying to do but if anyone can help with this it would be greatly appreciated. It should also be noted that, yes, I am fairly new to Swift and iOS development as a whole.

Answer 1

Yes you can do this fairly easily, although I haven't used XMLParser in a while.
Note: In my code below I have renamed your QUIZ to Question as the struct represents a single question, not a whole quiz (list of questions)
So you want an empty array to each item to as you parse it:
var quiz = [Question]() // quiz is a list of questions.
Then you want to track the current question you are working on
var currentQuestion: Question?
So then each time you start and end a Question element, you know you have finished parsing a single question, so add it to the list.
func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String] = [:]) {
if elementName == "Question" {
currentQuestion = Question()
}
}
func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
if elementName == "Question", let question = currentQuestion {
quiz.append(question)
}
}
So you are just parsing the XML document top to bottom. Once you come upon a opening Question element, create a question object, fill the rest in and then when you encounter a closing question element, add the current question to the list.
By the end of the document your quiz variable should contain all of the questions in the document.
EDIT:
So I had to make a few changes, the foundCharacters can come in parts so we need to keep track of it.
Here is a working playground which returns 2 questions (based on your sample XML above). Answer C is always blank, It looks like this is because of a newline char and the trim is cutting of the text, you may need to remove newlines and then just trim whitespace but this code will give you a good start.
import Foundation
let xmlData = """
<questions>
<question>
<clue> sample clue 1 </clue>
<correct_answer>2</correct_answer>
<enumeration>1</enumeration>
<info> sample info 1 </info>
<location_clue>Sample locationClue (5,5)</location_clue>
<option_a>Ans1</option_a>
<option_b>Ans2</option_b>
<option_c>Ans3</option_c>
</question>
<question>
<clue> sample clue 2 </clue>
<correct_answer>3</correct_answer>
<enumeration>2</enumeration>
<info> sample info 2 </info>
<location_clue>Sample locationClue (4,2)</location_clue>
<option_a>Ans1</option_a>
<option_b>Ans2</option_b>
<option_c>Ans3</option_c>
</question>
</questions>
""".data(using: .utf8)!
struct Question {
var question: String?
var clue: String?
var info: String?
var locationClue: String?
var answerA: String?
var answerB: String?
var answerC: String?
}
class MySuperXMLParser: NSObject, XMLParserDelegate {
private let parser: XMLParser
private var quiz = [Question]()
private var currentQuestion: Question?
private var currentElement: String?
private var foundCharacters = ""
init(data: Data) {
parser = XMLParser(data: data)
super.init()
parser.delegate = self
}
func parse() -> [Question] {
parser.parse()
return quiz
}
func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String] = [:]) {
if elementName == "question" {
currentQuestion = Question()
}
print("Started element: \(elementName)")
currentElement = elementName
}
func parser(_ parser: XMLParser, foundCharacters string: String) {
print("found characters: \(string)")
foundCharacters += string
}
func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
print("ended element: \(elementName), text = \(foundCharacters)")
let text = foundCharacters.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
switch currentElement
{
case "clue":
currentQuestion?.clue = text
break
case "info":
currentQuestion?.info = text
break
case "location_clue":
currentQuestion?.locationClue = text
break
case "option_a":
currentQuestion?.answerA = text
break
case "option_b":
currentQuestion?.answerB = text
break
case "option_c": currentQuestion?.answerC = text
default:
break
}
foundCharacters = ""
if elementName == "question", let question = currentQuestion {
print("adding question: \(question)")
quiz.append(question)
}
}
}
let parser = MySuperXMLParser(data: xmlData)
let quiz = parser.parse()
print(quiz.count, quiz)

Answer 2

If you don't mind using an external library, you can try XMLMapper.
Just use the following model classes:
class Questions: XMLMappable {
var nodeName: String!
var questions: [Question]?
required init(map: XMLMap) {
}
func mapping(map: XMLMap) {
questions <- map["question"]
}
}
class Question: XMLMappable {
var nodeName: String!
var clue: String?
var correct_answer: Int?
var enumeration: Int?
var info: String?
var location_clue: String?
var option_a: String?
var option_b: String?
var option_c: String?
required init(map: XMLMap) {
}
func mapping(map: XMLMap) {
clue <- map["clue"]
correct_answer <- map["correct_answer"]
enumeration <- map["enumeration"]
info <- map["info"]
location_clue <- map["location_clue"]
option_a <- map["option_a"]
option_b <- map["option_b"]
option_c <- map["option_c"]
}
}
And map your XML by calling map(XMLString:) function in XMLMapper:
let object = XMLMapper<Questions>().map(XMLString: xmlString)
print(object?.questions?.first?.clue ?? "nil")
Hope this helps.