iOS Learning Delegate design mode

In review, these was the steps for setting up the delegate pattern between the objects, where object A is the delegate for Object B and Object B would send out the messages:

1. Define a delegate @protocol for object B.

2. Give object B A property for that delegate protocol.

3. Make object B send messages to it delegate when something interesting happens, such as the user pressing the Cancel or Done buttons, or when it needs a piece of information.

4. Make object A conform to the delegate protocol. It should put the name of the protocol in its @interface line and implement the methods from the protocol.

5. Tell object B, Object A is now the its delegate.

Tips

1.if screen A (object a) launches screens B (Object B) then you don ' t want screens B to know too much about the screens that in Voked it (A).

2.Using a delegate helps to abstract the dependency from screen B in screen A.

3.Anytime you want one part of your app to notify another part about something, usually in order to update the screens, you Want to use delegates.

4.if screen A opens screens B, then a can give B the data it needs. You simply make a property for the this data on the screen B and then the screen a puts something to this property right before it m Akes screen B visible. To pass the data back from the B to a would use a delegate.

iOS Learning Delegate design mode