How can I encode a string to Base64 in Swift?

Question

I want to convert a string to Base64. I found answers in several places, but it does not work anymore in Swift. I am using Xcode 6.2. I believe the answer might be work in p

Answer 1

I don’t have 6.2 installed but I don’t think 6.3 is any different in this regard:

dataUsingEncoding returns an optional, so you need to unwrap that.

NSDataBase64EncodingOptions.fromRaw has been replaced with NSDataBase64EncodingOptions(rawValue:). Slightly surprisingly, this is not a failable initializer so you don’t need to unwrap it.

But since NSData(base64EncodedString:) is a failable initializer, you need to unwrap that.

Btw, all these changes were suggested by Xcode migrator (click the error message in the gutter and it has a “fix-it” suggestion).

Final code, rewritten to avoid force-unwraps, looks like this:

import Foundation

let str = "iOS Developer Tips encoded in Base64"
println("Original: \(str)")

let utf8str = str.dataUsingEncoding(NSUTF8StringEncoding)

if let base64Encoded = utf8str?.base64EncodedStringWithOptions(NSDataBase64EncodingOptions(rawValue: 0)) 
{

    println("Encoded:  \(base64Encoded)")

    if let base64Decoded = NSData(base64EncodedString: base64Encoded, options:   NSDataBase64DecodingOptions(rawValue: 0))
                          .map({ NSString(data: $0, encoding: NSUTF8StringEncoding) })
    {
        // Convert back to a string
        println("Decoded:  \(base64Decoded)")
    }
}

(if using Swift 1.2 you could use multiple if-lets instead of the map)

Swift 5 Update:

import Foundation

let str = "iOS Developer Tips encoded in Base64"
print("Original: \(str)")

let utf8str = str.data(using: .utf8)

if let base64Encoded = utf8str?.base64EncodedString(options: Data.Base64EncodingOptions(rawValue: 0)) {
    print("Encoded: \(base64Encoded)")

    if let base64Decoded = Data(base64Encoded: base64Encoded, options: Data.Base64DecodingOptions(rawValue: 0))
    .map({ String(data: $0, encoding: .utf8) }) {
        // Convert back to a string
        print("Decoded: \(base64Decoded ?? "")")
    }
}

Answer 2

Swift 3 / 4 / 5.1

Here is a simple String extension, allowing for preserving optionals in the event of an error when decoding.

extension String {
    /// Encode a String to Base64
    func toBase64() -> String {
        return Data(self.utf8).base64EncodedString()
    }

    /// Decode a String from Base64. Returns nil if unsuccessful.
    func fromBase64() -> String? {
        guard let data = Data(base64Encoded: self) else { return nil }
        return String(data: data, encoding: .utf8)
    }
}

Example:

let testString = "A test string."

let encoded = testString.toBase64() // "QSB0ZXN0IHN0cmluZy4="

guard let decoded = encoded.fromBase64() // "A test string."
    else { return } 

Answer 3

After all struggle I did like this.

func conversion(str:NSString)
{

    if let decodedData = NSData(base64EncodedString: str as String, options:NSDataBase64DecodingOptions(rawValue: 0)),
        let decodedString = NSString(data: decodedData, encoding: NSUTF8StringEncoding) {

        print(decodedString)//Here we are getting decoded string

After I am calling another function for converting decoded string to dictionary

        self .convertStringToDictionary(decodedString as String)
    }


}//function close

//for string to dictionary

func convertStringToDictionary(text: String) -> [String:AnyObject]? {
    if let data = text.dataUsingEncoding(NSUTF8StringEncoding) {
        do {
            let json = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? [String:AnyObject]

            print(json)
            if let stack = json!["cid"]  //getting key value here
            {
                customerID = stack as! String
                print(customerID)
            }

        } catch let error as NSError {
            print(error)
        }
    }
    return nil
}