Creating NSData from NSString in Swift

I'm trying to ultimately have an NSMutableURLRequest with a valid HTTPBody, but I can't seem to get my string data (coming from a UITextField) into a usable NSData object.

I've seen this method for going the other way:

NSString(data data: NSData!, encoding encoding: UInt)

But I can't seem to find any documentation for my use case. I'm open to putting the string into some other type if necessary, but none of the initialization options for NSData using Swift seem to be what I'm looking for.

In Swift 3

let data = string.data(using: .utf8)

---

In Swift 2 (or if you already have a NSString instance)

let data = string.dataUsingEncoding(NSUTF8StringEncoding)

---

In Swift 1 (or if you have a swift String):

let data = (string as NSString).dataUsingEncoding(NSUTF8StringEncoding)

---

Also note that data is an Optional<NSData> (since the conversion might fail), so you'll need to unwrap it before using it, for instance:

if let d = data {
    println(d)
}

Swift 4 & 3

Creating Data object from String object has been changed in Swift 3. Correct version now is:

let data = "any string".data(using: .utf8)

In swift 5

let data = Data(YourString.utf8)

Here very simple method

let data = string.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)

Swift 4

let data = myStringVariable.data(using: String.Encoding.utf8.rawValue)

// Checking the format
var urlString: NSString = NSString(data: jsonData, encoding: NSUTF8StringEncoding)

// Convert your data and set your request's HTTPBody property
var stringData: NSString = NSString(string: "jsonRequest=\(urlString)")

var requestBodyData: NSData = stringData.dataUsingEncoding(NSUTF8StringEncoding)!

To create not optional data I recommend using it:

let key = "1234567"
let keyData = Data(key.utf8)

Swift 4.2

let data = yourString.data(using: .utf8, allowLossyConversion: true)

Convert String to Data

extension String {
    func toData() -> Data {
        return Data(self.utf8)
    }
}

Convert Data to String

extension Data {
      func toString() -> String {
          return String(decoding: self, as: UTF8.self)
      }
   }