Cocoa & Objective-C: An Introduction

Introduction to Cocoa and Objective-C given to my colleagues of Electronlibre on August 28th, 2008.

Transcript

1. Cocoa & Objective-C An introduction August 28th, 2008
2. Cocoa & Objective-C • Introduction • Objective-C • Cocoa Touch • iPhone • “CurrencyConverter” Application • Books • References
3. Introduction
4. History • Objective-C • The “other” OO language based in C • Created by Brad Cox (~1980) • Smalltalk syntax around C • NeXT • The “other” company created by Steve Jobs • NeXTstep: the father of Cocoa
7. Legacy
10. Objective-C
11. The Language • Thin layer around C • Message-dispatch runtime • Static and dynamic (you choose) • The “real” father of Java: • http://cs.gmu.edu/~sean/stuff/java-objc.html
12. Comparison Objective-C Java @interface & @implementation class @protocol interface #import // files! import // classes! categories n/a id n/a
13. Characteristics • Single inheritance + interfaces (“@protocols”) • @protocols can have optional methods • Fields protected by default • Methods can be added to existing classes • Full introspection / reflection • Messages can be intercepted and forwarded • à la AOP!
14. Classes
15. Methods
16. Calling Methods • “Message Passing” ≠ “Method Call” [object method]; [object methodWithParam:parameter and:other]; • Interface and implementation are decoupled
17. The “id” type • Placeholder to any type: id name = @”Adrian”; • Similar to NSString* name = @”Adrian”; • In the latter form, we get compiler checks
18. Creating Objects • No “new” operator; static and instance methods used instead: MyClass *value = nil; value = [[MyClass alloc] init];
19. Creating Objects • Cannot create objects on the stack: • All objects are created on the heap!
20. Creating Objects // C++ // Memory freed when out of scope std::string name(“Adrian”); std::string *name = NULL; name = new std::string(“Adrian”); delete name;
21. Memory Management • Cocoa allows Garbage Collection only for desktop apps. • iPhone applications DO NOT use Garbage collection, but manual memory management.
22. Memory Management • Objects created using “alloc” have a “retain count” of “1”: // increments retain count [object retain]; // decrements retain count [object release];
23. Memory Management http://cocoadevcentral.com/d/learn_objectivec/
24. Memory Management • Only one rule: • “If you create an object with alloc or copy, send it a release message at the end of the function. If you create an object any other way, do nothing”
25. Cocoa Touch
26. Cocoa Touch • Reduced version of the Cocoa framework found in Mac OS X Leopard • Divided in two parts: • UIKit • Foundation
27. UIKit
28. iPhone OS
29. Address Book ABAddressBook ABMultiValue ABMutableMultiValue ABRecord ABGroup ABPerson
30. Accelerometer UIAccelerometer UIAccelerometerDelegate
31. Video MPMoviePlayerController
32. Location Services
33. Graphics & Animation CALayer NSGraphicsContext NSRect / NSMakeRect NSBezierPath NSColor
34. Camera & Photo Library UIImagePickerController UIImagePickerControllerDelegate UIImagePickerControllerSourceTypeCamera UIImagePickerControllerSourceTypePhotoLibrary
35. Code Security
36. More... • Audio • AudioToolbox • AudioUnit • CoreAudio • CoreMIDI • OpenAL • XML • WebKit • SQLite • Networking • CFNetwork • Bonjour
37. CurrencyConverter
38. CurrencyConverter • Simple application for the iPhone • Shows basic workflow • Use of • delegation • Interface Builder / Xcode integration • categories
39. Books
44. References
45. Objective-C http://cocoadevcentral.com/d/learn_objectivec/ http://www.faqs.org/faqs/computer-lang/Objective-C/faq/ http://cs.gmu.edu/~sean/stuff/java-objc.html http://www.mactech.com/articles/mactech/Vol.13/13.03/CandObjectiveCCompared/
46. C Tutorial for Cocoa http://cocoadevcentral.com/articles/000081.php
47. Naming Guidelines http://cocoadevcentral.com/articles/000082.php http://cocoadevcentral.com/articles/000083.php
48. Cocoa Tutorial http://cocoadevcentral.com/d/learn_cocoa/ http://cocoadevcentral.com/d/learn_cocoa_two/
49. Thanks!
50. Questions?