IOS开发之——登录加密也许用到的，反转字符串

- (NSString *)stringByReversed
{
// NSMutableString *s = [NSMutableString string];
// for (NSUInteger i=self.length; i>0; i--) {
// [s appendString:[self substringWithRange:NSMakeRange(i-1, 1)]];
// }
// return s;
unsigned long len;
len = [self length];
unichar a[len];
for(int i = 0; i < len; i++)
{
unichar c = [self characterAtIndex:len-i-1];
a[i] = c;
}
NSString *str1=[NSString stringWithCharacters:a length:len];
return str1;
}