how to let users drop pins in map view, that others can see

how to let users drop pins in map view, that others can see

how do i code a map view in which users can drop multiple pins, make
annotations and add pictures?
my question has several parts to it really. i know how to code a map view
in Xcode and how to put a pre-set pin however i want to be able to code
something a bit more complex as it works in relation to an app i'm hoping
to create!
1: how do i let a user of the app drop multiple pins to specify a certain
location?
2: once the user has dropped a pin i want that he is able to add
annotations and pictures?
3: finally i need that all the information of where the pins have been
dropped, the annotations and the pictures can be seen by all other people
using the app!
i have loked extensively into this and although i have found how to code
basic maps into an app i have not been able to code the follow up parts!
thank you for reading my question and would really appreciate any
suggestions that can be given. if you think there is a useful youtube
video or a blog that you think could help me please put it at the bottom
and i will look through it!