hexToBytes

NSStringHexToBytes.m

@interface NSString (NSStringHexToBytes)
-(NSData*) hexToBytes ;
@end



@implementation NSString (NSStringHexToBytes)
-(NSData*) hexToBytes {
  NSMutableData* data = [NSMutableData data];
  int idx;
  for (idx = 0; idx+2 <= self.length; idx+=2) {
    NSRange range = NSMakeRange(idx, 2);
    NSString* hexStr = [self substringWithRange:range];
    NSScanner* scanner = [NSScanner scannerWithString:hexStr];
    unsigned int intValue;
    [scanner scanHexInt:&intValue];
    [data appendBytes:&intValue length:1];
  }
  return data;
}
@end



/// example
unsigned char bytes[] = { 0x11, 0x56, 0xFF, 0xCD, 0x34, 0x30, 0xAA, 0x22 };
NSData* expectedData = [NSData dataWithBytes:bytes length:sizeof(bytes)];
NSLog(@"data %@", [@"1156FFCD3430AA22" hexToBytes]);
NSLog(@"expectedData isEqual:%d", [expectedData isEqual:[@"1156FFCD3430AA22" hexToBytes]]);