iOS开发 密码里面含有特殊字符如何处理传给后端

+ (NSString *)passWordToChange:(NSString *)string {
    NSString *pswStr = CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)string, NULL, CFSTR("!*'();:@&=+$,/?%#[]~`^-_|<>{}."), kCFStringEncodingUTF8));
    return pswStr;
}