Xcode Programing & iOS !!

import java.security.MessageDigest;
import java.io.FileInputStream;
public class SHA256 
{
    public static void main(String[] args)throws Exception
    {
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        FileInputStream fis = new FileInputStream("d:\\abc.txt");
        byte[] dataBytes = new byte[1024];
        int nread = 0;
        while ((nread = fis.read(dataBytes)) != -1) {
          md.update(dataBytes, 0, nread);
        };
        byte[] mdbytes = md.digest();
        //convert the byte to hex format method 1aa
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < mdbytes.length; i++) {
          sb.append(Integer.toString((mdbytes[i] & 0xff) + 0x100, 16).substring(1));
        }
        System.out.println("Hex format : " + sb.toString());
       //convert the byte to hex format method 2
        StringBuffer hexString = new StringBuffer();
     for (int i=0;i < mdbytes.length; i++) {
       hexString.append(Integer.toHexString(0xFF & mdbytes[i]));
     }
     System.out.println("Hex format : " + hexString.toString());
    }
}