int 转16进制
NSString *hexString = [NSString stringWithFormat:@"%@",[[NSString alloc] initWithFormat:@"%1x",整形参数]];

16进制转int
unsigned long uint_ch = strtoul([str2 UTF8String], 0, 16);
//将十六进制的字符串转换成NSString则可使用如下式:

• (NSString *)convertHexStrToString:(NSString *)str
  {
  if (!str || [str length] == 0)
  {
  return nil;
  }
  NSMutableData *hexData = [[NSMutableData alloc] initWithCapacity:8];NSRange range;if ([str length] % 2 == 0)
  {
  range = NSMakeRange(0,2);
  } else {
  range = NSMakeRange(0,1);
  }for (NSInteger i = range.location; i < [str length]; i += 2)
  { unsigned int anInt;
  NSString *hexCharStr = [str substringWithRange:range];
  NSScanner *scanner = [[NSScanner alloc] initWithString:hexCharStr];
  [scanner scanHexInt:&anInt];
  NSData *entity = [[NSData alloc] initWithBytes:&anInt length:1];
  [hexData appendData:entity];
  range.location += range.length;
  range.length = 2;
  }
  NSString *string = [[NSString alloc]initWithData:hexData encoding:NSUTF8StringEncoding];
  return string;
  }

`
//将NSString转换成十六进制的字符串则可使用如下方式:

• (NSString *)convertStringToHexStr:(NSString *)str {
  if (!str || [str length] == 0)
  {
  return @"";
  }
  NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
  NSMutableString *string = [[NSMutableString alloc] initWithCapacity:[data length]];
  [data enumerateByteRangesUsingBlock:^(const void *bytes, NSRange byteRange, BOOL *stop)
  { unsigned char dataBytes = (unsigned char)bytes;
  for (NSInteger i = 0; i < byteRange.length; i++)
  { NSString *hexStr = [NSString stringWithFormat:@"%x", (dataBytes[i]) & 0xff];
  if ([hexStr length] == 2)
  { [string appendString:hexStr];
  } else {
  [string appendFormat:@"0%@", hexStr];
  }
  }
  }];
  return string;
  }