How to send a POST request in Swift with a variable - php

Question

I am trying to send a POST request to a web server, however the value I am trying to send is in a variable named temperatureValue. The web server looks for the POST variable "temperature". This is how I am declaring my postData. How do I pass in this variable?
let postData = NSMutableData(data: "temperature=temperatureValue".dataUsingEncoding(NSUTF8StringEncoding)!)
The rest of the code for the POST is included below, but my main question is how to format the above to allow my variable temperatureValue to be saved into postData.
//Assign the url post address, post the data to the php page
let request = NSMutableURLRequest(URL: NSURL(string: "http://pi.access.com/stateBlinds.php")!,
cachePolicy: .UseProtocolCachePolicy,
timeoutInterval: 10.0)
request.HTTPMethod = "POST"
request.HTTPBody = postData
let session = NSURLSession.sharedSession()
let dataTask = session.dataTaskWithRequest(request, completionHandler: { (data, response, error) -> Void in
if (error != nil) {
print(error)
} else {
let httpResponse = response as? NSHTTPURLResponse
print(httpResponse)
}
})
dataTask.resume()

Answer 1

You can use string interpolation:
let temperatureValue = 10.5
request.HTTPBody = "temperature=\(temperatureValue)".dataUsingEncoding(NSUTF8StringEncoding)
If temperatureValue is an optional, though, you have to unwrap it.
let temperatureValue: Double? = 10.5
let postString: String
if let value = temperatureValue {
postString = "temperature=\(value)"
} else {
postString = "temperature="
}
request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)
Also note that this very simple example works only if dealing with very simple "values" (e.g. just alphanumeric with no spaces or special characters). If you take this pattern and try it with general strings, you have to percent-escape the value. But for simple numeric values, the above will suffice.