int to Byte[] and Byte[] to NSData and NSData to Byte[]

        int num = 160;

        SignedByte sb = (SignedByte)num;

        Byte b = (Byte)num;

        NSLog(@"b is %d,sb is %d",b,sb);

        Byte arr[4];

        for(int i=0; i<4; i++){

            arr[i] = num >> 24 - 8*i & 0xff;

        }

        NSData *data = [NSData dataWithBytes:&arr length:4];

        Byte *aa = (Byte *)[data bytes];

        for(int a=0; a<[data length]; a++){

            NSLog(@"aa[%d] is %d",a,aa[a]);

        }