My project was tier architecture, divided in to 3 main sections, UI,Business layer and data access layer.
At the presentation level we had used MVC pattern, so the UI and model was separated using controller class.
To share common data across all tiers we had used the singleton pattern.
Factory classes where used between each layer for decoupling and centralizing object creation to avoid code complication.
Iterator pattern was used to browse through middle tier objects thus providing a tight encapsulation.
The middle tier objects and their child objects where standardized using
template pattern for consistent vocabulary and naming convention for
Watch the below design pattern video which explains factory pattern