Composite pattern

A design pattern that solves this kind of structural problem is
called the Composite patternWith the Composite pattern,  we can compose our strokes and dots into a tree structure
so that we can treat each of the nodes uniformly.

Observation Pattern in Objective-C

There are three steps to using key-value observation:

• Send the addObserver:forKeyPath:options:context: message

to each object that is being observed.

• Override the method observeValueForKeyPath:ofObject:chan

ge:content: in the class definition of the object that is doing the

observing.

• Override the dealloc method and remove the observer reference

in the class definition of the object that is observing.

Iphone & Ipad patterns

IPAD Patterns

http://landingpad.org/
http://thoughtbot.com/

Pattrns
http://pttrns.com/
http://mobile-patterns.com/
http://www.lovelyui.com/

Andorid UI
http://www.androiduipatterns.com/