Get MIME type from Swift Data

MIME.swift

public enum MIMEType: String {
    case jpeg = "image/jpeg"
    case png = "image/png"
    case gif = "image/gif"
    case tiff = "image/tiff"
    case pdf = "application/pdf"
    case plainText = "text/plain"
    case anyBinary = "application/octet-stream"
}

public extension Data {
    var mimeType: MIMEType {
        var firstByte: __uint8_t = 0x00
        NSData(data: self).getBytes(&firstByte, length: 1)

        switch firstByte {
        case 0xFF:
            return .jpeg
        case 0x89:
            return .png
        case 0x47:
            return .gif
        case 0x49, 0x4D:
            return .tiff
        case 0x25:
            return .pdf
        case 0x46:
            return .plainText
        default:
            return .anyBinary
        }
    }
}