book

Pro Objective-C Design Patterns for iOS

Name: Pro Objective-C Design Patterns for iOS
Author: Carlo Chung
ISBN: 9781430233305

by Carlo Chung

April 2011

Intermediate to advanced

380 pages

8h 59m

English

Apress

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Copyright
About the Author
About the Technical Reviewer
Acknowledgments
Preface
I. Getting Your Feet Wet
1. Hello, Design Patterns!
1.1. What This Book Is1.2. What You Need Before You Can Begin1.3. What You Need to Know Before You Can Begin1.4. Design Déjà-vu1.5. The Origin of Design Patterns - Model, View, and Controller (MVC)1.5.1. Encapsulating Data and Basic Behaviors In Model Objects1.5.2. Presenting Information to the User with View Objects1.5.3. Tying up the Model to the View with Controller Objects1.5.4. MVC as a Compound Design Pattern1.6. Issues That Can Affect Your Design1.6.1. Programming To An Interface, Not An Implementation1.6.2. @protocol vs. Abstract Base Class (ABC)1.6.3. Object Composition vs. Class Inheritance1.7. Objects and Classes Used in this Book1.7.1. Class Diagram1.7.1.1. Protocol, Abstract Class, Concrete Class, and Category1.7.1.2. Instantiation1.7.1.3. Inheritance1.7.1.4. Acquaintance1.7.1.5. Aggregation1.7.1.6. Pseudocode1.7.2. Object Diagram1.8. How the Patterns are Organized1.9. Summary
2. A Case Study: Designing an App
2.1. Conceptualizing the Ideas2.2. Designing the Look-and-Feel2.3. Architectural Design2.3.1. View Management2.3.1.1. Transition from One View to Another2.3.1.2. Using a Mediator to Coordinate View Transitions2.3.2. Scribble Representation2.3.2.1. "What" Can Be Drawn Onscreen?2.3.2.2. Representing Marks with a Composite Structure2.3.2.3. Drawing a Scribble2.3.3. Representation of a Saved Scribble2.3.3.1. Capturing the State of a Scribble2.3.3.2. Restoring the State of a Scribble2.3.4. User Operations2.3.4.1. Browsing a List of Scribble Thumbnails2.3.4.2. Undo/Redo Scribbling2.3.4.3. Changing Stroke Colors and Sizes2.3.4.4. Deleting the Current Scribble Onscreen2.4. Reviewing the Patterns Used2.5. Summary
II. Object Creation
3. Prototype
3.1. What Is the Prototype Pattern?3.2. When Would You Use the Prototype Pattern?3.3. Shallow Copying vs. Deep Copying3.4. Using Object Copying in the Cocoa Touch Framework3.5. Implementing the Copy Method for the Mark Aggregate3.6. Using a Cloned Mark As a "Pattern Template"3.7. Summary

4. Factory Method
4.1. What Is the Factory Method Pattern?4.2. When Would You Use the Factory Method?4.3. Why Is It a Safe Approach to Creating Objects?4.4. Generating Different Canvases in TouchPainter4.4.1. Using Canvases4.5. Using Factory Methods Within the Cocoa Touch Framework4.6. Summary
5. Abstract Factory
5.1. Applying the Abstract Factory to the TouchPainter App5.2. Using the Abstract Factory Within the Cocoa Touch Framework5.3. Summary
6. Builder
6.1. What Is the Builder Pattern?6.2. When Would You Use the Builder Pattern?6.3. Building Characters in a Chasing Game6.4. Summary
7. Singleton
7.1. What Is the Singleton Pattern?7.2. When Would You Use the Singleton Pattern?7.3. Implementing a Singleton in Objective-C7.4. Subclassing a Singleton7.5. Thread Safety7.6. Using Singletons in the Cocoa Touch Framework7.6.1. Using the UIApplication Class7.6.2. Using the UIAccelerometer Class7.6.3. Using the NSFileManager Class7.7. Summary
III. Interface Adaptation
8. Adapter
8.1. What Is the Adapter Pattern?8.2. When Would You Use the Adapter Pattern?8.3. So You Know Delegation8.4. Implementing the Adapter Pattern with Objective-C Protocol8.4.1. Designing and Implementing a Stroke Color Changing Mechanism8.4.1.1. Defining SetStrokeColorCommandDelegate As a Target8.4.1.2. Implementing SetStrokeCommand As a Client8.4.1.3. Creating CommandSlider As an Adaptee8.4.1.4. Using PaletteViewController As an Adapter8.5. Implementing the Adapter Pattern with Objective-C Blocks in iOS 48.5.1. Declaring a Block Reference8.5.2. Creating a Block8.5.3. Using a Block As an Adapter8.6. Summary
9. Bridge
9.1. What Is the Bridge Pattern?9.2. When Would You Use the Bridge Pattern?9.3. Creating a Virtual Emulator for iOS9.4. Summary
10. Façade
10.1. What Is the Façade Pattern?10.2. When Would You Use the Façade Pattern?10.3. Providing a Simplified Interface to a Set of Interfaces in the Subsystem10.4. Using the Façade Pattern in the TouchPainter App10.5. Summary
IV. Decoupling of Objects
11. Mediator
11.1. What Is the Mediator Pattern?11.2. When Would You Use the Mediator Pattern?11.3. Managing View Transition in the TouchPainter App11.3.1. The Troubles of Modifying the Transition Logic11.3.2. Centralizing the Flow of the UI Traffic11.3.3. Using the CoordinatingController in the Interface Builder11.4. Summary
12. Observer
12.1. What Is the Observer Pattern?12.2. When Would You Use the Observer Pattern?12.3. Using the Observer Pattern in Model-View-Controller12.4. Using the Observer Pattern in the Cocoa Touch Framework12.4.1. Notifications12.4.2. Key-Value Observing12.5. Updating Strokes on the CanvasView in TouchPainter12.6. Summary
V. Abstract Collection
13. Composite
13.1. What Is the Composite Pattern?13.2. When Would You Use the Composite Pattern?13.3. Understanding the Use of Mark in TouchPainter13.4. Using Composites in the Cocoa Touch Framework13.5. Summary
14. Iterator
14.1. What Is the Iterator Pattern?14.2. When Would You Use the Iterator Pattern?14.3. Using Iterators in the Cocoa Touch Framework14.3.1. NSEnumerator14.3.2. Block-Based Enumeration14.3.3. Fast Enumeration14.3.4. Internal Enumeration14.4. Enumerating Vertices of a Scribble14.4.1. Enumerating Vertices of a Scribble (Internally)14.5. Summary
VI. Behavioral Extension
15. Visitor
15.1. What is the Visitor Pattern?15.2. When Would You Use the Visitor Pattern15.3. Rendering Marks in TouchPainter with Visitors15.4. What Else Can A Visitor Do?15.5. Can't I Just Use Categories Instead?15.6. Summary
16. Decorator
16.1. What Is the Decorator Pattern?16.2. When Would You Use the Decorator Pattern?16.3. Changing the "Skin" vs. "Guts" of an Object16.4. Creating Image Filters for UIImage16.4.1. Implementing Decorators with True Subclasses16.4.2. Implementing Decorators with Categories16.5. Summary
17. Chain of Responsibility
17.1. What Is the Chain of Responsibility Pattern?17.2. When Would You Use the Chain of Responsibility Pattern?17.3. Using the Chain of Responsibility Pattern in an RPG17.4. Summary
VII. Algorithm Encapsulation
18. Template Method
18.1. What Is the Template Method Pattern?18.2. When Would You Use the Template Method?18.3. Using the Template Method to Make a Sandwich18.4. Ensuring That the Template Method Is Working18.5. Adding an Extra Step to the Template Method18.6. Using the Template Method in the Cocoa Touch Framework18.6.1. Custom Drawing in the UIView Class18.6.2. Other Template Method Implementations in Cocoa Touch18.7. Summary
19. Strategy
19.1. What Is the Strategy Pattern?19.2. When Would You Use the Strategy Pattern?19.3. Applying Validation Strategies in UITextField19.4. Summary
20. Command
20.1. What Is the Command Pattern?20.2. When Would You Use the Command Pattern?20.3. Using the Command Pattern in the Cocoa Touch Framework20.3.1. NSInvocation Objects20.3.2. NSUndoManager20.3.2.1. Registering Undo Command Operations20.4. Implementing Undo/Redo in TouchPainter20.4.1. Implementing Drawing/Undrawing with NSUndoManager20.4.1.1. Adding Methods for Generating Drawing/Undrawing Invocations20.4.1.2. Adding Methods for Registering Undo/Redo Operations in NSUndoManager20.4.1.3. Modifying Touch Event Handlers for Invocations20.4.2. Home-Brewing Your Own Drawing/Undrawing Infrastructure20.4.2.1. Designing a Command Infrastructure20.4.2.2. Implementing the Command Classes20.4.2.3. Modifying CanvasViewController for the Commands20.4.3. Allowing the User to Activate Undo/Redo20.5. What Else Can a Command Do?20.6. Summary
VIII. Performance and Object Access
21. Flyweight
21.1. What Is the Flyweight Pattern?21.2. When Would You Use the Flyweight Pattern?21.3. Creating a Hundred-Flower Pool21.3.1. Designing and Implementing Sharable Flowers21.3.1.1. Implementing the FlowerView Class21.3.1.2. Implementing the FlowerFactory Class21.3.1.3. How Are FlowerView Objects Shared?21.3.1.4. Implementing Client Code21.4. Summary
22. Proxy
22.1. What Is the Proxy Pattern?22.2. When Would You Use the Proxy Pattern?22.3. Lazy-Loading an Image with a Virtual Proxy22.3.1. Designing and Implementing a Scribble Thumbnail View22.3.1.1. Implementing the ScribbleThumbnailView Class22.3.1.2. Implementing the ScribbleThumbnailViewImageProxy Class22.4. Using a Proxy Pattern in the Cocoa Touch Framework22.5. Summary
IX. State Of Object
23. Memento
23.1. What's the Memento Pattern?23.2. When Would You Use the Memento Pattern?23.3. Using the Memento Pattern in TouchPainter23.3.1. Saving a Scribble23.3.2. Restoring a Scribble23.3.3. Designing and Implementing ScribbleMemento23.3.3.1. Implementing the ScribbleMemento Class23.3.3.2. Modifying the Scribble Class23.3.3.3. Putting Everything Together with a Caretaker23.4. The Memento Pattern in the Cocoa Touch Framework23.5. Summary

Content preview from Pro Objective-C Design Patterns for iOS

Chapter 19. Strategy

Do you remember the last time you stuffed a bunch of different algorithms in the same block of code and used spaghetti of if-else / switch-case conditional statements to determine which one to use? The algorithms could be a bunch of functions/methods of similar classes that solve related problems. For example, I have a routine that validates some input data. The data itself can be of any data type (e.g., CGFloat, NSString, NSInteger, etc.). Each of the data types requires a different validation algorithm. If we can encapsulate each algorithm as an object, then we can eliminate a bunch of if-else / switch-case statements for data type checking in order to determine what algorithm to use.

In object-oriented software design, we ...

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Pro Objective-C Design Patterns for iOS

by Carlo Chung

Chapter 19. Strategy

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