Can we use firebase in with ios without Authentication?

I am using firebase database in my iOS application , but i don't want to use authentication by users.

How to set different pictures on different pins on map by using MapKit in Objective-C

How to set different image in all pin by using Mapkit and without using the delegate? I used below code, but it's not showing the image on the pin. Please suggest a proper method. Doesn't matter if you suggest a delegate method but it may work proper...

What are some alternatives to firebase that give me a real time changing values like firebase?

Can you please suggest me some good platforms for mobile app development for iPhone, and future scope about this?