iphone development · 2012-07-21 · iphone development: a brief introduction zachary bedell hpc...

iPhone Development:A Brief Introduction

Zachary BedellHPC Technologies, Inc.

[email protected]

1Saturday, November 7, 2009

Copyright ©2009 HPC Technologies, Inc.

PROJECT

DATE LOCATION07-NOV-2009 TECH VALLEY CODE CAMP

IPHONE DEVELOPMENTA BRIEF INTRODUCTION


[email protected]



ECOSYSTEM OVERVIEWPANTHERS AND TIGERS AND LEOPARDS, SNOW MY!



Getting Started(This is just a Simulation)

Intel® based Mac

Leopard or Snow Leopard

Your Immortal Soul (Sign the SDK Agreement)

10GB to burn

Knowledge of Objective-C (not optional)



Doing it for Real(Device Deployment)Unmodified iPhone or iPod Touch (any generation)

$99/year entry fee

Your 1st & 2nd born (Distribution & Paid Apps Agreements)

Time: Approval takes weeks to months

Chutzpah: No guarantee Apple will approve, no way to pre-screen ideas.



What you can ExpectRude, negative reviews over simple misunderstandings

Rampant application piracy (40-90%)

If you’re lucky: A modest residual income

If you’re insanely lucky (become next Flight Control): Modest full-time wages for a small team

Quite a lot of fun: One warm glowing email is worth a dozen scathing one-star reviews

Remember with client/server resourcesRemember with client/server resources



Today’s Agenda

Walkthrough of Xcode & Interface Builder

Intro to Objective-C Syntax

Important iPhone classes, program flow, event handling, and animation

Tour of a Trivial Application (ATOM Parser)



Bonus Points (Time Permitting)

Deeper look at Objective-C syntax & OO features

Static code analysis (CLANG)

Performance profiling (Instruments)

Packaging for Distribution



Technologies Used

Objective-C (no Objective-C++ today)

CoreData object persistence API

mogenerator - Xcode plugin for CoreData class generation. http://rentzsch.github.com/mogenerator/

Visually designed GUI (mostly, w/ manual tweaks)

SAX-based XML Parser for ATOM feeds



Who IS this guy???

Coding for 24 years

Mac OS X since 2004

iPhone since 2007 (the bad old days)

Moderately successful in the AppStore since opening day (BookShelf)



XCODE & INTERFACE BUILDER WALKTHROUGH



Don’t Go Away!

Deep Dive Session coming up next!



PROJECT

DATE LOCATION07-NOV-2009 TECH VALLEY CODE CAMP

IPHONE DEVELOPMENTPART II: DEEP DIVE


[email protected]



The Objective-C Language



Objective-C

Created by Brad Cox & Tom Love

Based on Smalltalk

Strict superset of C

ABI compatible -- call C from Obj-C “for free”



Different from C++

Send messages vs. Call methods

Actual implementation address determined at runtime, not compile time

Receiving object “asked” to do something, can do so how ever it pleases

Method look up slower than C++ virtual call, but aggressive in the runtime caching helps



Basic Syntax



1. SYNTAX INTRODUCTION



@interface MyClass : ParentClass { int m_member; id m_objectMember;}+ (void)classMethod;+ (id)objectWithThingy:(id)p_thingy;

- (void)instanceMethod;- (int)countForKind:(NSString*)p_kind;- (NSURL*)urlForItemId:(NSString*)p_id inFeed:(TAFeed*)p_feed;@end



#import “MyClass.h”

@implementation+ (void)classMethod {// ...}

/*! Get URL for the given item. */- (NSURL*)urlForItemId:(NSString*)p_id inFeed:(TAFeed*)p_feed { return nil;}@end



Basic Obj-C Syntax

Sending Messages:[target method:param];

#import instead of #include

String literals: @”foo”



Sending Messages

[myObject addThing:thing withCategory:cat];

Method name is addThing:withCategory:

Receiver is myObject

Params are thing & cat

Receiver may be nil (0) -- returns zero*



Types of Methods

+ means class (static) method

- means instance method

When written, method names include +/- and all the pieces: -urlForItemId:inFeed:

@selector() leaves off +/- (more on that later)



2. PROPERTIES



Properties@interface MyClass : NSObject { int noHungarian; NSString *m_thing; id m_dontTouch;}@property(assign) int noHungarian;@property(retain,nonatomic) NSString *thing;@property(readonly) id dontTouch;@end

@implementation MyClass@synthesize noHungarian;@synthesize thing = m_thing, dontTouch = m_dontTouch;@end

MyClass *mc; mc.thing = @”foo”;



Properties

@synthesize is optional

Provide some/all of your own accessors if you like:

- (void)setThing:(NSString*)p_thing { /* ... */ }

Can still @synthesize getter (or vice versa)

Naming is everything: property “foo” has:- (void)setFoo:(id)p_foo;- (id)foo; // Note: not getFoo



Using Objects



3. OBJECT INIT / CLEANUP



Object Instantiation

alloc/initMyClass *foo = [[MyClass alloc] init];

- (id)init { if((self = [super init])) { // Class specific initialization } return self;}




You MUST:

Call an init in super (usually “designated” init)

Assign result of super init call to “self”

Proceed only if return is non-nil

Be prepared for init to return a different object than alloc.




You May:

Create as many init’s as you want with different parameters

Create convenience methods to return autoreleased objects



Memory Management



Memory Management

Hybrid of reference counting & garbage collection

You “own” an object if you alloc, copy, or retain it.

You must release or autorelease all objects you own when done.

Mac has real garbage collection now, but not iPhone.

CLANG can help find leaks @ compile time

Instruments helps at debug time



Memory Managementalloc & copy return object w/ refCount==1

release decrements refCount immediately

autorelease dec’s next time flow reaches main event loop

Can “undo” an autorelease with a retain

-dealloc is called on object after refCount reaches zero (how long after is undefined)

MUST call [super dealloc] at end of -dealloc



Memory Management

All methods which return objects (except alloc & copy) return autorelease’d objects: refCount==1 now, but autorelease ensures it will reach zero at main run loop

retain objects you want to keep beyond run loop

do nothing, and objects will be dealloc’d at main run loop



NSNumber *ltuae = [NSNumber numberWithInt:42];[ltuae retain];

NSNumber *mine = [[NSNumber alloc] initWithInt:42];

[ltuae release];

return [mine autorelease];

retain/release aren’t really necessary here, but...

autorelease & return the target object for convenience

Memory Management



Memory ManagementCreate NSAutoreleasePool’s if you won’t get to main loop for a while:

NSAutoreleasePool *pool = [[NSAutoreleasePool] alloc] init];for(int i=0; i<1000000; i++) { // Do some stuff... if(i % 1000 == 0) { // Do it everyone once in a “while” [pool release]; // All autoreleased objects // free’d here. pool = [[NSAutoreleasePool] alloc] init]; }}[pool release]; pool = nil; // Final cleanup



Memory Managementautorelease is nice, but wasteful

Use alloc/init rather than convenience methods when:

In a loop

Performance is critical

Working w/ large objects (get them free’d ASAP!)

Okay: [NSArray arrayWithObjects: @”1”, @”2”, nil];

Better: [[NSArray alloc] initWithObjects: @”1”, @”2”, nil];



EVERY TIME YOU LEAK MEMORY...(PLEASE, THINK OF THE KITTENS!)

http://www.flickr.com/photos/ebola8mystinkymonkey/3732413869 - Used by permission



Cocoa Class Library



Mutable / Immutable

Most objects are immutable w/ mutable versions

NSString <- Set it only once

NSMutableString <- Change all you want

Better for threading, easier to debug, etc.



Collections

NSArray

NSDictionary

NSSet

Mutable versions of all

No generics ☹



Other Classes

HTTP requests

File manipulation

XML Parsing (Only SAX on iPhone)

HTML rendering (Safari / WebKit)

Defaults / Preferences

Concurrency - Operation Queue



Objective-C iPhone Specifics



Startup & Shutdown

main()->NSAppMain()->NIB->AppDelegate-applicationDidFinishLaunching:

-applicationWillResignActive:

-applicationWillTerminate:



View Controllers

Tables, back/forward navigation

Provide a single root UIView which OS displays, hides, animates as necessary



View Controllers - Initialization

-init / -awakeFromNib

-loadView -> -viewDidLoad -> -viewWillAppear: -> -viewDidAppear:

-viewWillDisappear: -> -viewDidDisappear: -> -viewDidUnload



UITableViewController

List of records, possibly grouped into sections

delegate provides controller behavior - responds to edits, taps on row, etc.

datasource provides model behavior - number of sections, number of items in each section, views for the table rows themselves



UINavigationController

Provides forward/back navigations for views

Contains other view controllers - often tables

viewcontrollers are pushed/popped on navigation

Handles animation automatically



UINAVIGATIONCONTROLLER & UITABLEVIEWCONTROLLER DEMO



Rotation & Autosizing

UIViewController

-willRotateToInterfaceOrientation:duration:

-willAnimateRotationToInterfaceOrientation:duration:

-didRotateFromInterfaceOrientation:

UIView

.autoresizesSubviews

.autoresizingMask



Animation

Most view properties can be animated automatically

[UIView beginAnimations:nil context:nil];myView.frame = CGRectMake(160, 240, 0, 0);[UIView commitAnimations];



ANIMATION DEMO



Debugging Tricks

NSZombie



Interprocess Communication

application:handleOpenURL:



TOUR OF A TRIVIAL APP



Advanced Object Oriented Topics



Advanced OO: ProtocolsMultiple inheritance** Of specification, not implementation

Think: Java interfaces

Formal or informal -- compiler enforces formal

Mac OS is mostly informal, iPhone mostly formal

Protocols are “adopted,” not “implemented”

No abstract/virtual methods - can throw exception at runtime if not implemented.



5. PROTOCOLS



@protocol Persistable - (void)save; - (void)load;@end

@interface MyClass : NSObject <Persitable> {}@end

@implementation MyClass- (void)save { /* ... */ }- (void)load { /* ... */ }



Advanced OO: Categories

Anyone can add methods to existing classes without source access.

Interfaces on steroids...



6. CATEGORIES



@interface NSString(Hashes) - (NSString*)md5; - (NSString*)sha1;@end

@implementation NSString(Hashes) - (NSString*)md5 { /* ... */ } - (NSString*)sha1 { /* ... */ }

#import “NSString+Hashes.h”// ...NSString *md5 = [@”some string” md5];



Threading

NSLock & children (wrappers on pthreads)

@synchronized(object) { ... }

⚠Only touch GUI from main thread

[NSThread isMainThread];

[object performSelectorOnMainThread:@selector(something:) withObject:foo waitUntilDone:NO];



Fast Enumeration

NSArray *list = [NSArray arrayWithObjects:@”1”, @”2”, @”3”, nil];for(NSString *item in list) { NSLog(@”%@”, item);}



Dynamic Objective-C



Selectors

Like function pointers

SEL foo = @selector(someMethod:withArg:);[receiver performSelector:foo withObject:bar withObject:baz];

NSArray *foo = ...;[foo makeObjectsPerformSelector:@selector(saveToDisk)];



Key-Value Coding

Dynamic property access

[myObject valueForKey:@”foo”] == myObject.foo

[myObject setValue:@”blue” forKey:@”color”];

Works automatically if you use @property’s



If it Quacks...“Supports” monkey patching, duck punching, etc.

void Swizzle(Class c, SEL orig, SEL new) { Method origMethod = class_getInstanceMethod(c, orig); Method newMethod = class_getInstanceMethod(c, new); if(class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod))) { class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(newMethod)); } else { method_exchangeImplementations(origMethod, newMethod); }}

Swizzle([MyClass class], @selector(someMethod:), @selector(myImpl:));



TYPES: STATIC OR DUCK -- YOUR CHOICE



4. STATIC OR DUCK TYPES



Static or Dynamic Typesid foo;foo = @”some string”;foo = [NSNumber numberWithInt:42];

NSString *foo;foo = @”some string”;/* This is a compile warning: */foo = [NSNumber numberWithInt:42];

Note: id holds any Objective-C object. typedef NSObject *id; /*(More or less...)*/



Static or Dynamic Types

Restrict with protocols:- (void)addPersitable:(id<Persitable>)p_item;

More on Protocols next...



Static Code Analysis with CLANG



CLANG STATIC CODE ANALYSIS



Performance & Memory Profiling



PROFILING WITH INSTRUMENTS



Packaging for Distribution



Ad-hoc Distribution

Create an IPA file

Distribute it with your provisioning profile (from Apple)

Install both to authorized devices using iTunes or iPhone Configuration Utility



Ad-hoc Distribution

IPA’s are ZIP files:

PayLoad/ iTunesArtwork <-- JPEG, 512px square iTunesMetadata.plist MyBundle.app/ _CodeSignature/ <-- Code signing (Xcode) embedded.mobileprovision <-- Profile MyBundle <-- Binary Default.png resources / etc.



Just ZIP up the .app bundle

Upload through iTunes Connect

Then you wait......

AppStore Distribution



About the ScriptsAssumes using git-svn for revision control:

Git for local development w/ dcommit to svn

SVN for integration builds on a server

Uses SVN rev for versioning & can extract it automatically in both Git & SVN environments

Packages IPA for Ad-Hoc or ZIP for AppStore

Evolved from Mac app & older iPhone SDK - a bit crufty

Many sanity checks may no longer be necessary (but don’t hurt) -- from older SDK bugs

Some Bash, some Perl, some PHP, but it works...82Saturday, November 7, 2009


BUILD SCRIPTS


The End...Questions?

@[email protected]

iphonebookshelf.com/!tvccSlides & Code at:


iphone development · 2012-07-21 · iphone development: a brief introduction zachary bedell hpc...

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