将HEX NSString转换为NSData

Question

将HEX NSString转换为NSData我正在尝试将十六进制转换NSString为NSData（我正在使用下面附加的代码）。以下是输出：<00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000>这看起来与我完全无关。关于哪里出错的任何想法/建议？NSString *strData = @"72ff63cea198b3edba8f7e0c23acc345050187a0cde5a9872cbab091ab73e553";NSLog(@"string Data length is %d",[strData length]);NSMutableData *commandToSend= [[NSMutableData alloc] init];unsigned char whole_byte;char byte_chars[2];int i;for (i=0; i < [strData length]/2; i++) {    byte_chars[0] = [strData characterAtIndex:i*2];    byte_chars[1] = [strData characterAtIndex:i*2+1];    whole_byte = strtol(byte_chars, NULL, [strData length]);    [commandToSend appendBytes:&whole_byte length:1]; }NSLog(@"%@", commandToSend);    

Answer 1

NSString *command = @"72ff63cea198b3edba8f7e0c23acc345050187a0cde5a9872cbab091ab73e553";command = [command stringByReplacingOccurrencesOfString:@" " withString:@""];NSMutableData *commandToSend= [[NSMutableData alloc] init];unsigned char whole_byte;char byte_chars[3] = {'\0','\0','\0'};int i;for (i=0; i < [command length]/2; i++) {
    byte_chars[0] = [command characterAtIndex:i*2];
    byte_chars[1] = [command characterAtIndex:i*2+1];
    whole_byte = strtol(byte_chars, NULL, 16);
    [commandToSend appendBytes:&whole_byte length:1]; }NSLog(@"%@", commandToSend);

Answer 2

这可能更有用，Apple已经共享了NSData类别。

的NSData + HexString.m

代码是：

@implementation NSData (HexString)// Not efficent+(id)dataWithHexString:(NSString *)hex{
    char buf[3];
    buf[2] = '\0';
    NSAssert(0 == [hex length] % 2, @"Hex strings should have an even number of digits (%@)", hex);
    unsigned char *bytes = malloc([hex length]/2);
    unsigned char *bp = bytes;
    for (CFIndex i = 0; i < [hex length]; i += 2) {
        buf[0] = [hex characterAtIndex:i];
        buf[1] = [hex characterAtIndex:i+1];
        char *b2 = NULL;
        *bp++ = strtol(buf, &b2, 16);
        NSAssert(b2 == buf + 2, @"String should be all hex digits: %@ (bad digit around %d)", hex, i);
    }

    return [NSData dataWithBytesNoCopy:bytes length:[hex length]/2 freeWhenDone:YES];}@end