weareopensource/Swift

/**
 * Dependencies
 */

import UIKit

/**
* Extension
*/

extension Data {
    private static let mimeTypeSignatures: [UInt8: String] = [
        0xFF: "image/jpeg",
        0x89: "image/png",
        0x47: "image/gif",
        0x49: "image/tiff",
        0x4D: "image/tiff",
        0x25: "application/pdf",
        0xD0: "application/vnd",
        0x46: "text/plain"
        ]

    var mimeType: String {
        var c: UInt8 = 0
        copyBytes(to: &c, count: 1)
        return Data.mimeTypeSignatures[c] ?? "application/octet-stream"
    }

    var imgExtension: String {
        var c: UInt8 = 0
        copyBytes(to: &c, count: 1)
        return String(Data.mimeTypeSignatures[c]?.split(separator: "/")[1] ?? "unknown")
    }
}