Present by MB team at eXo Platform SEA

1. How to develop an iOS application
Objective C – Xcode – iOS
Le Thanh Quang
Mobile team
April 19th 2012

2. Agenda
Objective-C in brief
Xcode
iOS frameworks
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3. Objective-C
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4. Objective-C – What is it?
Simple extension of the C language
Adds object-oriented capabilities to C language
Runtime system (C library)
Dynamic typing
Dynamic binding
GCC/Clang compiler supports both C and Objective-C
Apple donated Objective-C for GNU project (open source)
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5. Objective-C – Who use?
Apple Inc.
Mac OS X developers
Cocoa framework
Core animation, Core data, etc
iOS developers
Cocoa touch framework
Core animation, Core data, etc
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6. Objective-C – Why should I (Java developer) care?
Make up your mind with new code designs
iPhone/iPad devices become popular rich user agents in
enterprise market
eXo Platform 3.5, cloud-workspaces.com are integrated with iOS
based devices and Android family
Play around for fun or profit in free time ;)
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7. Objective-C – History
Appeared in 1983
Designed by Tom Love & Brad Fox
Major implementations GCC, Clang
Influenced by Smalltalk, C
OS Cross-platform
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8. Objective-C and Java
Java
Almost everywhere
… except iPhone
Objective-C
Platform
Mac OS X
iPhone, iPad, ...
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9. Objective-C and Java Message Syntax
Java
myString.toString()
Objective-C
* Square brackets for message expressions
[myString description]
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10. Objective-C and Java Method arguments
Java
person.setFirstName(“Fred”)
Objective-C
* Arguments are delimited by colons
[person setFirstName:@”Fred”]
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11. Objective-C and Java Object Data types
Java
Employee emp = new Employee();
Objective-C
* Objective-C objects are dynamically allocated structs
Employee *emp = [[Employee alloc] init];
* Providing generic object type, id
id emp2 = [[Employee alloc] init];
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12. Objective-C and Java Object Data types
Java
* Constructors
Employee emp = new Employee();
Objective-C
Employee *emp = [[Employee alloc] init];
* Creation methods are just methods
* Calls to super can occur anywhere within a method
* Inheritance is straight-forward
* Memory allocations and initialization are separate steps
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13. Objective-C and Java Prefix vs Package path
Java
java.lang.String s = new String(“hello”);
Objective-C
* Objective-C doesn't provide namespaces
* Frameworks and libraries use prefixes by convention to avoid collision
NSString *s = [NSString alloc] initWithString:@”Hi”];
==> NS is prefix for classes of Foundation Framework.
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14. Objective-C and Java Method prototypes
Java public void sayHello() {
…
}
Objective-C
* Methods declared in .h file, implemented in .m
* Instance methods prefixed with -
* Class methods prefixed with +
Ex:
// Method declarations
- (id)init;
- (id)alloc;
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15. Objective-C and Java Method prototypes
Objective-C
* No method overloading
* Runtime system looks up methods by name rather than signatures
* Method names can be composed of multiple sections
Ex:
- (void)addEmployee:(Employee *)emp withTitle:
(NSString *)title
Name of method is addEmployee:withTitle
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16. Objective-C and Java Class
Java
...
Objective-C
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17. Objective-C and Java Anatomy of Class Declaration
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18. Objective-C Class Implementation
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19. Objective-C and Java Class
Java
...
Objective-C
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20. Objective-C – Memory management
* Reference counting
– (id)retain; // increase retain count
– (id)release; // decrease retain count
– (id)autorelease; // release with a delay
– (void)dealloc; // call by release when retain
count = 1
* Creation methods set retain count to 1
– Creation methods whose names start with alloc or new or
contain copy
– Those who call creation methods MUST call either release or
autorelease also
– Never call dealloc directly
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21. Objective-C – Memory management
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22. Objective-C – Categories
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23. Objective-C – Using category
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24. Objective-C – Blocks
A block of code
– A sequence of statements inside {}
– Start with the magical character caret ^
Ex:
[aDictionary enumerateKeysAndObjectsUsingBlock:^(id key,
id value, BOOL *stop) {
NSLog(@“value for key %@ is %@”, key, value);
if ([@“ENOUGH” isEqualToString:key]) {
*stop = YES;
}
}];
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25. Objective-C – Blocks
A block of code
– Can use local variables declared before the block inside the
block
– But they are read only!
Ex:
double stopValue = 53.5;
[aDictionary enumerateKeysAndObjectsUsingBlock:^(id key,
id value, BOOL *stop) {
NSLog(@“value for key %@ is %@”, key, value);
if ([@“ENOUGH” isEqualToString:key] || ([value
doubleValue] == stopValue)) {
*stop = YES;
stoppedEarly = YES; // ILLEGAL
}
}];
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26. Objective-C – Blocks
When do we use blocks in iOS?
– Enumeration
– View Animations
– Sorting (sort this thing using a block as the comparison method)
– Notification (when something happens, execute this block)
– Error handlers (if an error happens while doing this, execute this
block)
– Completion handlers (when you are done doing this, execute this
block)
And a super-important use: Multithreading
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27. Xcode
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28. Xcode
IDE for iPhone projects
– Build
– Run (Simulator, device)
– Debug
– Source code management (SCM)
– Documentation
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29. Xcode
Automatically maintain build scripts
Display logical grouping of files
No package paths
By default, groups not mapped to folder structure
Resources
Automatically bundled with executable
Frameworks
Linked at compile time; no classpath needed
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30. Xcode - Interface Builder
Visual GUI design tool
Doesn't generate code
Working with “freeze-dried” objects
– Archived (serialized) in .nib files
– Dynamically loaded
– Objects deserialized at load time
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31. Xcode
DEMO
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32. iOS
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33. iOS – Layered architecture
C libraries and system calls
Core services (C libraries and Objective-C frameworks)
Media Layer (C libraries and Objective-C frameworks)
Cocoa touch
Foundation framework
UIKit
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34. iOS – Design Patterns
MVC Pattern
Delegate Pattern
Target/Action Pattern
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35. iOS – MVC Pattern
Model View
Controller
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36. iOS – MVC Pattern
Model
– Manages the app data and state
– No concerned with UI or presentation
– Often persists somewhere
– Same model should be reusable, unchanged in different
interfaces.
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37. iOS – MVC Pattern
View
– Present the Model to the user in an appropriate interface
– Allows user to manipulate data
– Does not store any data
– Easily reusable & configurable to display different data
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38. iOS – MVC Pattern
Controller
– Intermediary between Model & View
– Updates the view when the model changes
– Updates the model when the user manipulates the view
– Typically where the app logic lives.
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39. iOS – Delegation Pattern
Control passed to delegate objects to perform application specific
behavior
Avoids need to subclass complex objects
Many UIKit classes use delegates
– UIApplication
– UITableView
– UITextField
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40. iOS – Target/Action Pattern
When event occurs, action is invoked on target
object
Target: myObject
sayHello Action: @selector(sayHello)
Event: UIControlEventTouchUpInside
Controller
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41. References
Training for newcomer of Mobile team -
http://int.exoplatform.org/portal/g/:spaces:mobile/mobile/local._wiki.WikiPortl
et/group/spaces/mobile/iOS_Training
Jonathan Lehr -
http://jonathanlehr.files.wordpress.com/2009/09/objective-c-and-java.pdf
stanford.edu - http://www.stanford.edu/class/cs193p/cgi-bin/drupal/
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42. Questions?
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