NSData与 byte 和NSString转换

一.byte数组生成NSData

    Byte byte[] = {0x40,0xff,0x04,0x80,0x01,0x66,0xef,0xda,0xb9,0x0d,0x0a};

   NSData *adata = [[NSDataalloc] initWithBytes:bytelength:11];

   NSData *imageData = [NSDatadataWithBytes:byte length:sizeof(byte)];

   NSLog(@"%@",imageData);

//可用于解析NSData

   Byte *bytes = (Byte *)[adatabytes];

   NSString *hexStr=@"";

   for(int i=0;i<[adatalength];i++)

    {

       NSString *newHexStr = [NSStringstringWithFormat:@"%x",bytes[i]&0xff];///16进制数

       if([newHexStr length]==1)

            hexStr = [NSStringstringWithFormat:@"%@0%@",hexStr,newHexStr];

       else

            hexStr = [NSStringstringWithFormat:@"%@%@",hexStr,newHexStr];

    }

    NSLog(@"bytes的16进制数为:%@",hexStr);

二.

    

    ///// 将16进制数据转化成Byte 数组

    NSString *hexString =@"3e435fab9c34891f"; //16进制字符串

   int j=0;

   

    Byte *bytes;  //

   for(int i=0;i<[hexString length];i++)

    {

        int int_ch; /// 两位16进制数转化后的10进制数

        

        unichar hex_char1 = [hexString characterAtIndex:i];////两位16进制数中的第一位(高位*16)

       int int_ch1;

       if(hex_char1 >= '0' && hex_char1 <='9')

            int_ch1 = (hex_char1-48)*16;  //// 0 的Ascll - 48

       else if(hex_char1 >= 'A' && hex_char1 <='F')

            int_ch1 = (hex_char1-55)*16;//// A 的Ascll - 65

       else

            int_ch1 = (hex_char1-87)*16;//// a 的Ascll - 97

        i++;

        

        unichar hex_char2 = [hexString characterAtIndex:i];///两位16进制数中的第二位(低位)

       int int_ch2;

       if(hex_char2 >= '0' && hex_char2 <='9')

            int_ch2 = (hex_char2-48);//// 0 的Ascll - 48

       else if(hex_char1 >= 'A' && hex_char1 <='F')

            int_ch2 = hex_char2-55;//// A 的Ascll - 65

       else

            int_ch2 = hex_char2-87;//// a 的Ascll - 97

        

        int_ch = int_ch1+int_ch2;

        NSLog(@"int_ch=%d",int_ch);

        bytes[j] = int_ch; ///将转化后的数放入Byte数组里

        j++;

    }

    NSData *newData = [[NSData alloc] initWithBytes:bytes length:sizeof(bytes)];

    NSLog(@"newData=%@",newData);