Is there any ways I can get image url from GMSPlace object? For example, if the GMSPlace represents a restaurant, then is there any way I can get that restaurant's image via google api? Or any other service from google?
This is now possible; see here:
https://developers.google.com/places/ios-api/photos
There are other versions of loadPlacePhoto with more arguments than are shown there if you need them:
https://developers.google.com/places/ios-api/reference/interface_g_m_s_places_client