How to pass data between viewcontrollers

Question

I have a fairly complex application at this point, and feel as though the way I am handling data is not up to scratch.

So I have started taking some steps towards making my app more MVC friendly. The first of which, I have gone from having inline parser methods in all of my ViewControllers to creating a dedicated parser class.

Its not hard to call I just set up the class then call the initializer method I have made which I pass the data to for my request.. everything in my object class works sweet I get a whole bunch of return data from the server that I am parsing.. but then this is where I get abit lost.

How do I get that data back to the ViewController that called it? I have worked a little with protocols and delegates.. but I dont know how that would fit into this.

Here is an graphical example of what I am trying to achieve.

So as above View controller calls the initalization method of the object class which connects to the DB downloads the data, and then parses that data. The issue I am having is how do I then get that data to ViewController2..

what is the most appropriate and future proof way of doing this?

Answer 1

Try to send a local notification using NSNotificationCenter. Register your ViewController2 as a listener, then upon receiving the notification, call your data model (singleton!?) for the data.

Answer 2

If you want to broadcast data from your object to all view controllers the good way to do this will be by notifications (NSNotificationCenter). You could also write a methods with completion blocks inside your parser object.

Answer 3

A custom -init method does wonders. For instance, I needed to instantiate and push a picker preloaded with the array from the previous screen, so I defined -(id)initWithArray:(NSArray*)array in the second view, then just called secondView = [[SecondView alloc]initWithArray:_population]; then pushed it. Remember to get ownership of any object you pass before it is deallocated and destroyed!