iOS 中与硬件通讯数据转换

十六进制字符串转NSData

-(NSData *)converHexStrToData:(NSString *)hexString {
    NSMutableData *data = [[NSMutableData alloc] init];
    unsigned char whole_byte;
    char byte_chars[3] = {'\0','\0','\0'};
    if (hexString.length%2) {
        //防止丢失半个byte
        hexString = [@"0" stringByAppendingString:hexString];
    }
    int i;
    for (i = 0; i < [hexString length]/2; i++) {
        byte_chars[0] = [hexString characterAtIndex:i * 2];
        byte_chars[1] = [hexString characterAtIndex:i * 2 + 1];
        whole_byte = strtol(byte_chars, NULL, 16);
        [data appendBytes:&whole_byte length:1];
    }
    return data;
}

NSData转十六进制字符串

-(NSString *) converDataToHexString:(NSData *)data
{
    if (data == nil) {
        return nil;
    }
    NSMutableString* hexString = [NSMutableString string];
    const unsigned char *p = [data bytes];
    for (int i=0; i < [data length]; i++) {
        [hexString appendFormat:@"%02x", *p++];
    }
    return hexString;
}

十六进制字符串转普通字符串

-(NSString *)stringFromHexString:(NSString *)hexString {
    char *myBuffer = (char *)malloc((int)[hexString length] / 2 + 1);
    bzero(myBuffer, [hexString length] / 2 + 1);
    for (int i = 0; i < [hexString length] - 1; i += 2) {
        unsigned int anInt;
        NSString * hexCharStr = [hexString substringWithRange:NSMakeRange(i, 2)];
        NSScanner * scanner = [[NSScanner alloc] initWithString:hexCharStr];
        [scanner scanHexInt:&anInt];
        myBuffer[i / 2] = (char)anInt;
    }
    NSString *unicodeString = [NSString stringWithCString:myBuffer encoding:4];
    return unicodeString;
}