16進制編碼，轉成字符串
+ (NSString *)hexStringForData:(NSData *)data {
static const u_char HexCharMap[] = "0123456789abcdef";
Byte* bytes = (Byte*) [self bytes];
Byte* bytesHex = (Byte*) malloc([self length]*2);
for (NSUInteger i = 0, j = 0; i < [self length]; i++, j+=2) {
bytesHex[j+1] = HexCharMap[ bytes[i] & 0x0f ];
bytesHex[j ] = HexCharMap[(bytes[i] & 0xf0) >> 4];
}
return [[NSString alloc] initWithBytesNoCopy:bytesHex length:[self length]*2 encoding:(NSASCIIStringEncoding) freeWhenDone:YES];
}
16進制編碼逆過程
+ (NSData *)dataFromHexString:(NSString *)hexString {
NSUInteger size = [hexString length] / 2;
Byte* result = (Byte*) malloc(size);
bzero(result, size);
const char * cstring = [hexString cStringUsingEncoding:NSUTF8StringEncoding];
for (int i = 0, j = 0; i < size; i++, j += 2) {
result[i] = (Byte) ((digittoint(cstring[j]) << 4) | digittoint(cstring[j+1]));
}
return [NSData dataWithBytesNoCopy: result length:size freeWhenDone:YES];
}
總結
無意中搜到了C函數 digittoint，已經可以把16進制字符轉成數值，所以欣喜之余，發現可以拋棄網上的NSScaner方案（不斷構造新scanner來解析）。如果剛好你看到，覺得有用，那就留個贊。：）
