Objective-C for C# and Java

DevelopersJaxCodeCamp 2012

Who am I

•David Fekke

•.NET Developer by day, iOS by night

•Presenter JaxMUG, JaxDug, JaxJug, JSSUG

•Mac User 1986

JaxMUG

Meet once a month at the Southside Library

jaxmug.com

Jesse Eisenberg

QuickTime™ and a decompressor

are needed to see this picture.

The Apple Way

Assumptions

•Somewhat familiar with OO concepts

•Used a language like Java, C# or C++

•Open minded

•Actually used an iPhone, iPad or iPod Touch

Requirements

•You need a Intel Mac with Mac OS X

•Some knowledge of OO concepts

•Xcode tools (FREE)

•iOS (SDK)

iOS Platform

•ARM Processor

•128/256/512/1024 MB RAM

•BSD UNIX

•Mach Microkernel

•COCOA APIs

COCOA

•COCOA is a OO Framework

•Based on NextStep

•Mostly written in Objective-C

•iOS Devices use COCOA Touch

Cocoa Touch

Media

Core Services

Core OS

COCOA Framework•NS (NextStep)

•CF (Core Foundation)

•CA (Core Animation)

•CI (Core Image)

•Core Data

•OpenGL ES

COCOA Conventions

•Most classes begin with NS, I.E. NSObject, NSString, NSArray or NSNumber

•Designed around MVC pattern

•Heavy use of delegation

•iOS specific components based on UIKit

Tiobe Programming Index

Position Language

1 C

2 Java

3 Objective-C

4 C++

5 C#

Objective-C•Somewhere in-between C++ and Java

•Created by Brad Cox and Tom Love in 1982

•Based on C with SmallTalk like extentions

•Used in COCOA, OpenStep and GNUStep

•Class based OO language

-(BOOL)validateNumRangeWithStartNumber:(int)startNumber EndNum:(int) endNumber{

if (startNumber >= endNumber){

UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"End value Too Small" message:@"Sorry" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

[alertView show];[alertView release]; return YES;

} else {return NO;

}}

Obj-C vs C#

Obj-C C#[[object method]

method];obj.method().method();

Memory Pools Garbage Collection +/- static/instancenil null

(void)methodWithArg:(int)value {}

void method(int value) {}

YES NO true false@protocol interface

Objective-C Structure

•Obj-C Class composed of two files: header and implementation, or .h and .m

•header uses the @interface and implementation uses @implementation

#import <UIKit/UIKit.h>

@interface LottoRandomAppDelegate : NSObject <UIApplicationDelegate> { UIWindow *window;}

@property (nonatomic, retain) IBOutlet UIWindow *window;

@end

#import "LottoRandomAppDelegate.h"

@implementation LottoRandomAppDelegate

@synthesize window;

- (void)applicationDidFinishLaunching:(UIApplication *)application {

// Override point for customization after application launch [window makeKeyAndVisible];}

- (void)dealloc { [super dealloc];}

@end

Properties

•Objective-C 2.0

•@property (strong) NSString *myStr;

•@synthesize myStr = _myStr;

•No longer need @synthesize keyword in iOS 6.0

Property Getters and

Setters@synthesize myStr = _myStr;

-(NSString *)myStr{ return _myStr;}

-(void)setMyStr:(NSString *)aMyStr{ _myStr = aMyStr;}

@interface extension

@interface MasterViewController () { NSMutableArray *_objects;}@end

Categories

•Similar to method extensions and partial classes

•You can add methods to classes out side of the implementation file

@interface NSString (reverse)-(NSString *) reverseString;@end

@implementation NSString (reverse) -(NSString *) reverseString{ NSMutableString *reversedStr; int len = [self length];  // Auto released string reversedStr = [NSMutableString stringWithCapacity:len];   // Probably woefully inefficient... while (len > 0) [reversedStr appendString:[NSString stringWithFormat:@"%C", [self characterAtIndex:--len]]];   return reversedStr;} @end

Blocks

•C constructs for performing closures

•Similar to Lamda expressions in C#

•^{ ... Code goes here ... }

•Newer Obj-C APIs require blocks

•Used heavily in GCD

dispatch_queue_t myQueue = dispatch_queue_create("get people list", NULL); dispatch_async(myQueue, ^{ NSURL *myURL = [NSURL URLWithString:@"http://192.168.1.70/APISamples/api/people"];

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:myURL]; [request setHTTPMethod:@"GET"]; [request setValue:@"application/json" forHTTPHeaderField:@"Accept"]; NSURLResponse *response = nil; NSError *myErr; NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&myErr]; _objects = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&myErr]; dispatch_async(dispatch_get_main_queue(), ^{ [self.tableView reloadData]; }); // Ending main queue }); // End myQueue

Selectors•SEL type defines a method

signature

•-(void)setAction:(SEL)aSelector

•SEL mySelector;

•mySelector = @selector(drawMyView:);

•[myButton setAction:mySelector];

Objective-C Literals

•New in iOS 6 and Mac OS X 10.8

•NSArray *array = @[ @"Hello", NSApp, [NSNumber numberWithInt:42] ];

• NSDictionary *dictionary = @{@"name" : NSUserName(),@"date" : [NSDate date],@"processInfo" : [NSProcessInfo processInfo]};

Memory Management

•C used methods like malloc and free

•Obj-C uses object retain pool

•Garbage Collection on the Mac, but not on the iOS Devices

•Use ARC for future implementations

ARC

•Automatic Reference Counting

•Not Garbage Collection

•Compiler adds memory management into the compiled code

•Use Strong and Weak keywords to give hint to the compiler

MVC

•Model-View-Controller

•COCOA has Controller classes

•UIViewController Class

•Views are in the XIB (NIB) files or StoryBoards

Controllers

•iPhone Apps commonly have multiple views

•Controllers can Segue to each View

•Navigation Controller used to load different views

•UINavigationController

SDK Tools

•Xcode 4.5 IDE

•Interface Builder (Views)

•Instruments (Profiler tool)

•iPhone Simulator

Xcode 4.5

•LLVM, Clang and GCC compiler 4.2

•Support for Obj-C, C++, Python and Ruby (iPhone only uses Obj-C & C++)

•Code editor with code completion

•Support for GIT, SVN and CVS

Interface Builder•Tool for laying out interfaces

•Built into Xcode

•StoryBoards for Mobile

•Also works with older XIB and NIB files

•Bind Actions and Outlets in Controllers

Demo

Internet Resources

•http://developer.apple.com

•http://developer.apple.com/iphone/library/documentation/Cocoa/Conceptual/ObjectiveC/

•http://www.stanford.edu/class/cs193p/cgi-bin/index.php

•http://www.cocoadev.com/

Book Resources

•COCOA Programming For Mac OS X by Aaron Hillegass

•iPhone Developer’s Cookbook by Erica Sadun

•APress Books

Mono Touch

•Develop iPhone Apps with C#

•Xamarin IDE

•Ahead of time compilation

•Works with IB

PhoneGap

•HTML, CSS and JavaScript

•Compiles into an .app that can be uploaded to the app store

•Native vs. Run everywhere

•Also Sencha Touch

Contact

•davidfekke at gmail dot com

•twitter.com/davidfekke

•http://www.fekke.com/blog/

•Please come out to the JaxMUG

Questions?