Slides from a presentation I gave on Cocoa Design Patterns - software design patterns that are suitable and common within Apple's Cocoa and Cocoa Touch frameworks using Objective C

1. Cocoa Design
Patterns
Stewart Gleadow
February 2010

3. Timeline
1976 1980 1986 1988 1996 2000 2007 2011
Apple iPhone
Original Objective C
acquires mania
Smalltalk
NeXT
NeXT
& OS X Mac
Commerically
NeXTSTEP & app
licensed
Cocoa store
Smalltalk
Objective C 2.0

4. C
Objective C

5. Objective C Syntax
Definition:
- (void)textDidChangeFrom:(NSString *)old to:(NSString *)newText;
{
}
Calling:
[textField textDidChangeFrom:@”old text” to:@”new text”];

6. ?

8. Template
MVC Enumerators Proxy
Method
Targets &
Flyweight Singleton Delegates
Actions
Responder
Notifications Hierarchies Invocations
Chain

9. Template
MVC Enumerators
Iterator Proxy
Method
Targets &
Flyweight Singleton Delegates
Actions
Responder
Chain of
Notifications Hierarchies
Obser ver Composite Responsibility Invocations
Command
Chain

10. Template
MVC Enumerators
Iterator Proxy
Method
Targets &
Flyweight Singleton Delegates
Actions
Responder
Chain of
Notifications Hierarchies
Obser ver Composite Responsibility Invocations
Command
Chain

11. Template Method
MyView.h
#import <UIKit/UIKit.h>
@interface MyView : UIView
{
// instance variables go here
}
@end

12. Template Method
MyView.m
#import "MyView.h"
@implementation MyView
- (void)drawRect:(CGRect)rect;
{
// Drawing code.
}
@end

13. Delegate
@protocol TTURLRequestDelegate <NSObject>
@optional
- (void)requestDidStartLoad:(TTURLRequest*)request;
- (void)requestDidFinishLoad:(TTURLRequest*)request;
@end

14. Delegate
@implementation MyDelegate
- (void)requestDidStartLoad:(TTURLRequest*)request;
{
// start loading indicator?
}
- (void)requestDidFinishLoad:(TTURLRequest*)request;
{
// stop loading indicator
// do something awesome
}
@end

15. Delegate
TTURLRequest *request;
request = [TTURLRequest requestWithURL:url delegate:myDelegate];

16. Targets & Actions
UIButton *addButton;
addButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button addTarget:myButtonReceiver
action:@selector(addButtonWasPressed:)
forControlEvents:UIControlEventTouchUpInside];

18. Enumerator

19. Proxy

20. Flyweight

21. Singleton
[[UIApplication sharedApplication] delegate];

22. Notifications
&
Invocations

23. More?
• Cocoa Design Patterns, by Erik M.
Buck, Donald A.Yacktman
• (Advanced) Cocoa Programming
for Mac OS X - Aaron Hillegass
• Apple Developer Docs (http://
developer.apple.com)
• CocoaHeads (http://
groups.google.com/group/
cocoaheadsau)

25. Stewart Gleadow
Thoughtworks
sgleadow@thoughtworks.com
@stewgleadow