How to convert a String to a Float with Swift 2.0?

Question

I am trying to convert a string I load from an xml file to a float so i can set a slider value to 86.

When I use this code, it prints 0.0 ? but it has to be 86 !

Does somebody know why and how I can fix this ?

    var strXMLData:String = ""
    var currentElement:String = ""
    var passData:Bool=false
    var passName:Bool=false
    var parser = NSXMLParser()
    var string = ""

     let urlToSend: NSURL = NSURL(string: url)!
            // Parse the XML
            parser = NSXMLParser(contentsOfURL: urlToSend)!
            parser.delegate = self

            let success:Bool = parser.parse()

            if success {
                print("parse success!")

                print(strXMLData)

                string = strXMLData

                var float = (string as NSString).floatValue
                VolumeSlider.setValue(float)
                print(float)



            } else {
                print("parse failure!")
            }




            if(WCSession.isSupported()){
                self.session = WCSession.defaultSession()
                self.session.delegate = self
                self.session.activateSession()

    }
    }




    func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) {
        currentElement=elementName;
        if(elementName=="e2current")
        {
            if(elementName=="e2current"){
                passName=true;

            }
            passData=true;
        }

    }
    func parser(parser: NSXMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
        currentElement="";
        if(elementName=="e2current")
        {
            if(elementName=="e2current"){
                passName=false;
            }
            passData=false;
        }

    }

    func parser(parser: NSXMLParser, foundCharacters string: String) {
        if(passName){
            strXMLData=strXMLData+"\n\n"+string
        }

        if(passData)
        {
            print(string)
        }
    }

    func parser(parser: NSXMLParser, parseErrorOccurred parseError: NSError) {
        NSLog("failure error: %@", parseError)
    }

I am here. No worries. Sadly, I don't see what's the issue yet :/ — Coder1000
– Coder1000, Commented May 13, 2016 at 19:41
I am confused with what you are actually trying to do. You get a URL response, and need to parse out a string value that represents a float value? So the string would say "86.0"? — Siriss
– Siriss, Commented May 13, 2016 at 19:47

JoakimE · Accepted Answer · 2016-05-13 19:57:24Z

1

I've used this solution earlier. Don't know why your code didn't work, but at least this get's the job done...only with several lines of code.

var textNumber = "123456.789"
let numberFormatter = NSNumberFormatter()
numberFormatter.numberStyle = NSNumberFormatterStyle.DecimalStyle
let theNumber = numberFormatter.numberFromString(textNumber)
var floatValue = Double(theNumber!) //123456.789

answered May 13, 2016 at 19:57

JoakimE

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3 Comments

JoakimE Over a year ago

Are you sure that the number your are receiving are not 0.0?

Quinn Donkers Over a year ago

it is a good code, when you use it how you do. but keep in mind i have to go from string to float from the received string of the xml file

JoakimE Over a year ago

I use this to receive a number stored as a String. Then I use this code to convert it to a number. Do you know what value your received xml is?

Sulthan · Accepted Answer · 2016-05-13 20:08:55Z

After going through your parsing code, we can basically simplify it into the following:

Set passData to true when we are inside the element:

func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) {
    if (elementName == "e2current")  {
        passData = true;
    }
}

Set passData to false when we are not inside the element:

func parser(parser: NSXMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
    if (elementName == "e2current") {
        passData = false;
    }
}

Save the value when we are inside the element

func parser(parser: NSXMLParser, foundCharacters string: String) {
    if (passData){
        strXMLData = string
    }
}

Note that when you start adding \n\n to the string, you won't be able to parse that value.

A more sensible implementation would probably be:

var elementStack: [String] = []

func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) {
    elementStack.append(elementName)
}

func parser(parser: NSXMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
    elementStack.removeLast()
}

func parser(parser: NSXMLParser, foundCharacters string: String) {
    if (elementStack.last == "e2current") {
        strXMLData = string
    }
}

Sulthan · Accepted Answer · 2016-05-13 20:28:34Z

1

I got it working guys !

I had to change the value when I received it in the viewDidLoad but in the func parser(parser: NSXMLParser, foundCharacters string: String) {

thank you guys but i got it working know.

 func parser(parser: NSXMLParser, foundCharacters string: String) {
    if(passName){
        strXMLData=strXMLData+"\n\n"+string
    }

    if(passData)
    {
        print(string)

        let numberFormatter = NSNumberFormatter()
        numberFormatter.numberStyle = NSNumberFormatterStyle.DecimalStyle
        let theNumber = numberFormatter.numberFromString(string)
        let floatValue = Float(theNumber!)

        print(floatValue)

        VolumeSlider.setValue(floatValue)

    }
}

edited May 13, 2016 at 20:28

Sulthan

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answered May 13, 2016 at 20:09

Quinn Donkers

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