普通字符串转换为十六进制的。
- (NSString *)hexStringFromString:(NSString *)string{
NSData *myD = [string dataUsingEncoding:NSUTF8StringEncoding];
Byte *bytes = (Byte *)[myD bytes];
//下面是Byte 转换为16进制。
NSString *hexStr=@"";
for(int i=0;i<[myD length];i++)
{
NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff];///16进制数
if ([newHexStr length]==1)
hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
else
hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
}
return hexStr;
}

十六进制转换为普通字符串的。
- (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];
NSLog(@"字符串%@",unicodeString);
return unicodeString;
}

数字转十六进制字符串
- (NSString *)stringWithHexNumber:(NSUInteger)hexNumber{
char hexChar[6];
sprintf(hexChar, "%x", (int)hexNumber);
NSString *hexString = [NSString stringWithCString:hexChar encoding:NSUTF8StringEncoding];
return hexString;
}

十六进制字符串转数字
- (NSInteger)numberWithHexString:(NSString *)hexString{
const char *hexChar = [hexString cStringUsingEncoding:NSUTF8StringEncoding];
int hexNumber;
sscanf(hexChar, "%x", &hexNumber);
return (NSInteger)hexNumber;
}

将NSData转换成十六进制的字符串
- (NSString *)convertDataToHexStr:(NSData *)data {
if (!data || [data length] == 0) {
return @"";
}
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;
}

将十六进制字符串转换成NSData
- (NSData *)convertHexStrToData:(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;
}
NSLog(@"hexdata: %@", hexData);
return hexData;
}