58

I am receiving a base64String from webservice response in NSData, how to convert that base64String to String in swift?

    //Code
    var jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as! NSDictionary  // Response JSON from webservice
    var base64String : String = ""
    base64String = jsonResult["Base64String"] as! String  // Retrieve base64String as string from json response
    println("Base64String Alone: \(base64String)")

// Code to decode that base64String
let decodedData = NSData(base64EncodedString: base64String, options: NSDataBase64DecodingOptions(rawValue: 0))
                                    println("Decoded:  \(decodedData)")
                                    let decodedString = NSString(data: decodedData!, encoding: NSUTF8StringEncoding)
                                    println(decodedString) // Prints nil

Encode and decode of base64String works well for the files containing only text, if a file contains some table formats/images both encoding and decoding gives an invalid base64String. How to convert a file into base64String encode and decode whatever the contents of file ? File formats are doc, docx, pdf, txt

Advance thanks for any help !

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0

5 Answers 5

Reset to default
147

Try this:

let base64Encoded = "YW55IGNhcm5hbCBwbGVhc3VyZS4="

var decodedString = ""
if let decodedData = Data(base64Encoded: base64Encoded) {
    decodedString = String(data: decodedData, encoding: .utf8)!
}

if !decodedString.isEmpty {
    print(decodedString)
} else {
    print("Oops, invalid input format!")
}

Make sure your base 64 encoded string is valid.

WARNING (edit)

In most base64 decoding implementations like Java, the padding-character is not needed, but Data(base64Encoded:) returns nil if it's missing.

Swift 5 solution; use String.fromBase64(_:) instead, after implementing like:

extension Data {
    /// Same as ``Data(base64Encoded:)``, but adds padding automatically
    /// (if missing, instead of returning `nil`).
    public static func fromBase64(_ encoded: String) -> Data? {
        // Prefixes padding-character(s) (if needed).
        var encoded = encoded;
        let remainder = encoded.count % 4
        if remainder > 0 {
            encoded = encoded.padding(
                toLength: encoded.count + 4 - remainder,
                withPad: "=", startingAt: 0);
        }

        // Finally, decode.
        return Data(base64Encoded: encoded);
    }
}

extension String {
    public static func fromBase64(_ encoded: String) -> String? {
        if let data = Data.fromBase64(encoded) {
            return String(data: data, encoding: .utf8)
        }
        return nil;
    }
}

As mentioned on editor's profile, above edit's code allows Apache 2.0 license as well, without attribution need.

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5 Comments

I had tried this code but this receives following error "fatal error: unexpectedly found nil while unwrapping an Optional value". How to fix?
make sure your base64Encoded string is valid, because the string in the question is not valid.
I had a word document which contains images and table format data, tried to convert that word document to base64String, encoding went fine but if i decode it it gives "fatal error, found nil while unwrapping an optional value". Is it possible to encode and decode base64String word document which contains images and table formats in swift?
@nRewik, swift 3 please
this solution appends = at the end and not prefixes = in the front like in the comment
38

Swift extension is handy.

extension String {
    func base64Encoded() -> String? {
        return data(using: .utf8)?.base64EncodedString()
    }

    func base64Decoded() -> String? {
        guard let data = Data(base64Encoded: self) else { return nil }
        return String(data: data, encoding: .utf8)
    }
}

"heroes".base64Encoded() // It will return: aGVyb2Vz
"aGVyb2Vz".base64Decoded() // It will return: heroes
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Comments

15

i've made an update to Ashok Kumar S answer to add filler character when string size is not divisible by 4, raising an exception and returning nil 

extension String {
func base64Encoded() -> String? {
    return data(using: .utf8)?.base64EncodedString()
}

func base64Decoded() -> String? {
    var st = self;
    if (self.count % 4 <= 2){
        st += String(repeating: "=", count: (self.count % 4))
    }
    guard let data = Data(base64Encoded: st) else { return nil }
    return String(data: data, encoding: .utf8)
}
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1 Comment

That's what I need !
8

You can encrypt/decrypt base64 strings using this extension:

public extension String {


    var base64Decoded: String? {
        guard let decodedData = Data(base64Encoded: self) else { return nil }
        return String(data: decodedData, encoding: .utf8)
    }

    var base64Encoded: String? {
        let plainData = data(using: .utf8)
        return plainData?.base64EncodedString()
    }
}

To Encode:

"Hello World!".base64Encoded

Result is an Optional string: "SGVsbG8gV29ybGQh"

To Decode:

"SGVsbG8gV29ybGQh".base64Decoded

Result is an Optional string: "Hello World!"

Source

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Comments

5

The above answers are core, but i had an error like

fatal error, found nil while unwrapping an optional value

The solution is adding options

extension String {
//: ### Base64 encoding a string
    func base64Encoded() -> String? {
        if let data = self.data(using: .utf8) {
            return data.base64EncodedString()
        }
        return nil
    }

//: ### Base64 decoding a string
    func base64Decoded() -> String? {
        if let data = Data(base64Encoded: self, options: .ignoreUnknownCharacters) {
            return String(data: data, encoding: .utf8)
        }
        return nil
    }
}

and use it safely 

var str = "HelloWorld"
if let base64Str = str.base64Encoded() {
    print("Base64 encoded string: \"\(base64Str)\"")
    if let trs = base64Str.base64Decoded() {
        print("Base64 decoded string: \"\(trs)\"")
    }
}
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