1.URL编码

NSString *encodeURL = [url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

2.URL解码

NSString *decodeURL = [url stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

ios 9.0中已经替换此方法

NSString *encodedURL = [url stringByAddingPercentEncodingWithAllowedCharacters:(nonnull NSCharacterSet *)];
NSString *decodedURL = [url stringByRemovingPercentEncoding];

• (NSString )stringByAddingPercentEscapesUsingEncodingExt:(NSStringEncoding)enc stringWith:(NSString )str
  {
  if([str respondsToSelector:@selector(stringByAddingPercentEncodingWithAllowedCharacters:)] == YES)
  {
  NSCharacterSet set = [[NSCharacterSet characterSetWithCharactersInString:@"!'();:@&=+$,/?%#[]"] invertedSet];
  return [str stringByAddingPercentEncodingWithAllowedCharacters:set];
  }
  else
  {

pragma clang diagnostic push

pragma clang diagnostic ignored "-Wdeprecated-declarations"

    //        NSString * newString = (__bridge_transfer NSString *)
    NSString * newString = ( NSString *)
    CFURLCreateStringByAddingPercentEscapes(NULL,
                                            (__bridge CFStringRef)str,
                                            NULL,
                                            (CFStringRef)@"!*'();:@&=+$,/?%#[]",
                                            CFStringConvertNSStringEncodingToEncoding(enc));

pragma clang diagnostic pop

    return newString;
}

}