Why is my variable returning a nil after being converted to an int?

Question

I'm taking data from an api and storing it in a string variable. When I print the variable it returns what I'm looking for but when I try to convert it to an int using the .toInt method it returns a nil?

func getWeather() {
    let url = NSURL(string: "http://api.openweathermap.org/data/2.5/weather?q=London&mode=xml")

    let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {
        (data, response, error) in
        if error == nil {
            var urlContent = NSString(data: data, encoding: NSUTF8StringEncoding) as NSString!
            var urlContentArray = urlContent.componentsSeparatedByString("temperature value=\"")
            var temperatureString = (urlContentArray[1].substringWithRange(NSRange(location: 0, length:6))) as String
            println(temperatureString) // returns 272.32
            var final = temperatureString.toInt()
            println(final) //returns nil
            println(temperatureString.toInt())
            self.temperature.text = "\(temperatureString)"
        }
    }
    task.resume()
}

score 4 · Accepted Answer · answered Mar 20 '15 at 00:55

4

Even simpler, though slightly a trick, you can use integerValue:

temperatureString.integerValue

Unlike toInt, integerValue will stop converting when it finds a non-digit (it also throws away leading spaces.

If temperatureString is a String (rather than an NSString), you'll need to push it over:

(temperatureString as NSString).integerValue

answered Mar 20 '15 at 00:55

Rob Napier

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Yup, that's exactly what I was looking for! – Nikola Jankovic Mar 20 '15 at 01:02
Believe it or not, I just had this bug tonight converting some C code to Swift (and my toInt call failed for the same reason). So I happened to have just researched it… – Rob Napier Mar 20 '15 at 02:07

score 1 · Answer 2 · edited May 23 '17 at 11:56

1

That's because 272.32 is not an integer.

You could convert it to a Float.

edited May 23 '17 at 11:56

Community

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answered Mar 20 '15 at 00:38

Thilo

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Even so, wouldn't it just drop the decimal points and store it as 272? – Nikola Jankovic Mar 20 '15 at 00:40
Nope you're absolutely right, I just checked and 252 returns the value while any float returns a nil. Thanks for the help! – Nikola Jankovic Mar 20 '15 at 00:42

score 0 · Answer 3 · answered Mar 20 '15 at 00:41

0

272.32 isn't an Integer. If your temperature string is an NSString, you can do this to convert it:

Int("272.32".floatValue)

answered Mar 20 '15 at 00:41

kellanburket

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Why is my variable returning a nil after being converted to an int?

3 Answers3