Autocomplete query using Firebase. (iOS)

I'm trying to query a list of food items from my Firebase database. The app has a UITextfield where the user can type the search word for the food item. I have already implemented basic code for this to work using the below code.

NSString *searchString = [sender.text lowercaseString];

[[[[[self.ref queryOrderedByChild:@"fuudTitleCapped"] queryLimitedToLast:5] queryStartingAtValue:searchString] queryEndingAtValue:[NSString stringWithFormat:@"%@uf8ff",searchString]] observeSingleEventOfType:FIRDataEventTypeValue withBlock:^(FIRDataSnapshot *snapshot) {
    NSLog(@"%@ Key %@ Value", snapshot.key,snapshot.value);
}];

My database is structured like in the image below

What I want is to order the results by the key "fuudPrice".

Can anybody suggest me a way to do this??