Swift base64 decoding returns nil

Question

I am trying to decode a base64 string to an image in Swift using the following code:

let decodedData=NSData(base64EncodedString: encodedImageData, options: N         


        

Answer 1

When the number of characters is divisible by 4, you need to avoid padding.

private func base64PaddingWithEqual(encoded64: String) -> String {
  let remainder = encoded64.characters.count % 4
  if remainder == 0 {
    return encoded64
  } else {
    // padding with equal
    let newLength = encoded64.characters.count + (4 - remainder)
    return encoded64.stringByPaddingToLength(newLength, withString: "=", startingAtIndex: 0)
  }
}

Answer 2

This helped me:

extension String {
    func fromBase64() -> String? {
        guard let data = Data(base64Encoded: self.replacingOccurrences(of: "_", with: "="), options: Data.Base64DecodingOptions(rawValue: 0)) else {
            return nil
        }

        return String(data: data, encoding: .utf8)
    }
}

Usage:

print(base64EncodedString.fromBase64())

Answer 3

Another one-line version:

let length = encoded64.characters.count
encoded64 = encoded64.padding(toLength: length + (4 - length % 4) % 4, withPad: "=", startingAt: 0)

Answer 4

(Swift 3) I been in this situation, Trying to get the data using base64 encoded string returns nil with me when I used this line

let imageData = Data(base64Encoded: strBase64, options: .ignoreUnknownCharacters)

Tried padding the string and didn't work out too

This is what worked with me

func imageForBase64String(_ strBase64: String) -> UIImage? {

    do{
        let imageData = try Data(contentsOf: URL(string: strBase64)!)
        let image = UIImage(data: imageData)
        return image!
    }
    catch{
        return nil
    }
}

Answer 5

Check the content of your decodedData variable and look for this prefix "data:image/png;base64", I had this issue and noticed that my String base64 had a prefix like this, so I used this approached and it worked

extension String {
func getImageFromBase64() -> UIImage? {
    guard let url = URL(string: self) else {
        return nil
    }
    do {
        let data = try Data(contentsOf: url)
        return UIImage(data: data)
    } catch {
        return nil
    }

}

}

Answer 6

It's make problem with special character, but an interesting point is if we use NSData and NSString then it's working fine.

static func decodeBase64(input: String)->String{
        let base64Decoded = NSData(base64Encoded: input, options:   NSData.Base64DecodingOptions(rawValue: 0))
            .map({ NSString(data: $0 as Data, encoding: String.Encoding.utf8.rawValue) })

        return base64Decoded!! as String
}