An Introducon to iPhone Developmentdfleck/iPhone.pdfAn Introducon to iPhone Development ... • Really needs vi bindings… ;) ... • Cocoa with Objecve‐C

An Introduc+on to iPhone Development

Karl Majer [email protected]

[email protected]

Ge>ng Started

•  Minimal Prerequisites – Hardware

•  Touch Device ( iPhone/iPod ) ($300‐$500) –  Either device will work fine, you’ll need access to both for tes+ng –  You don’t need real touch hardware to start development, you can use the simulator to get going

•  Intel Mac (mini/MB/MP) ($499 ‐ $5000+) –  No, you don’t need a dual 32” Cinema display Mac Pro with 8 Cores and 32G of ram. Take that $12k and pay for a few more semesters of school

–  A Macbook (white model) is more than sufficient and frequently seen around campus and a mini is perfectly adequate.

–  Latest models aren’t required, get a refurb from the Apple Store or find a used Intel model on craigslist and save some money

5/1/09 2 [email protected]

Ge>ng Started

•  Minimal Prerequisites – Soaware

•  iPhone SDK (Free) –  2.2.1 Latest prod, 3.0 in Beta –  Includes:

»  Xcode »  Interface Builder »  iPhone Simulator

•  OSX 10.5


Ge>ng Started

•  Minimal Prerequisites –  Licenses

•  Apple Developer Keys –  This takes a up to week or two and costs $99/yr for a personal license,

$300/yr for a corporate license •  Developer is granted a key for a generated iden+ty and creates a profile

•  Developer registers devices with apple as development devices •  Devices are added to the profile and cer+ficates are downloaded from Apple

•  Profile is added to Xcode and then installed into device •  User created app can then be installed •  Step by step guide found on developer.apple.com, accessible aaer you’ve enrolled and paid for your keys


Ge>ng Started •  iPhone v Simulator

–  Performance •  Network •  Graphics •  Disk I/O •  It’s a soaware simulator, not a

hardware emulator –  Filesystem Access different

•  iPhone allows write to only Documents directory

•  Simulator allows writes to app bundle directory

–  Touch func+onality •  Simulator adequate for basic

touch/swipe –  No access to accelerometers

(no shake/+lt) –  Orienta+on change menu

driven process

5/1/09 [email protected] 5

Ge>ng Started

•  iPhone v iPod Touch – Base system func+onality

•  iPod lacks phone •  iPod lacks microphone

•  iPod lacks a camera •  iPod touch has a larger drive •  iPod touch has lower cost point


iPhone v Mac Development

•  Mac is a standard Unix machine –  Plenty of memory, disk, swap,etc

•  iPhone is severely resource constrained – Memory management cri+cal

•  Host swaps when out of memory, iPhone crashes

–  iPhone is a sandboxed environment •  Filesystems on iPhone severely restricted •  Apps cannot interact with anything else outside of its app bundle

•  Interac+on with Hardware done exclusively through API calls.


Xcode

•  The Standard Apple IDE •  Integrated Debugger, Doc Browser, Class Browser, standard Color Highligh+ng, etc.

•  Text auto comple+on –  Incredibly Useful

•  Mul+language – ObjC / ObjC++ / C / C++ / Java / Cocoa / Applescript

•  Really needs vi bindings… ;) 5/1/09 8 [email protected]

Xcode ‐ Editor


Xcode – Debugger


Interface Builder

•  The standard Apple tool for developing UIs. •  Same tool for use with na+ve OSX applica+ons as well as iPhone Apps – Experience directly useful between plaporms

•  Drag and Drop UI Design •  Applica+on look/feel limited to the UIKit library – User images can be used for most buqons/icons/etc to try and alleviate generic look


Interface Builder


Interface Builder


Development Languages

•  Objec+ve C – Older Language, 1980s – C was extended with SmallTalk support and was retrofiqed to support OOP

– Popularized by NeXT – Primarily used today for Mac OSX and iPhone programming

– Support can be built into GCC – NSFoo prefix throughout the code is a reference to NeXTStep


Development Languages

•  Cocoa – A collec+on of APIs wriqen in ObjC referred to as the Frameworks •  Founda+on Kit – provides core func+onality. Ie, String type, iterators, data storage, almost anything with an NSFoo prefix (NSString, NSData, NSDate)

•  Applica+on Kit – provides all graphics func+onality for applica+ons

– Also derived from NeXT –  Interac+on with Framework is typically in ObjC using Xcode and Interface Builder


Objec+ve C

•  Method Comparisons –  Compare the C++

•  (void) someClass::doSomething(int foo, int bar); •  Called as myClass.doSomething(1,0);

–  To the ObjC •  –(void)doSomething(NSInteger: foo andInt: NSInteger bar); •  Called as [myFunc doSomething:1 andInt:0] •  ObjC > 2.0 (OSX 10.5+) supports dot.style.nota+on

•  Declaring and alloca+ng a variable. –  NSString *myStr; // declare myStr; –  myStr = [[NSString alloc] init]; // allocated it –  NSString *myStr2 = [[NSString alloc] initWithFormat:@”%s”, @”hello

world”]; // declare, alloc, and populate


Objec+ve C / Cocoa

•  Common Founda+on Types – NSString – NSData – NSMutableArray – NSURL

•  C Types s+ll valid –  int, char, etc


Objec+ve C / Hello World

•  HelloWorld.h #import <Founda+on/Founda+on.h>

@interface HelloWorld : NSObject { // this class has no instance variables }

// we have one instance method ‐  (void)printHelloWorld;

@end

•  HelloWorld.m #import "HelloWorld.h"

@implementa+on HelloWorld

// now we implement the instance method ‐ (void)printHelloWorld { // NSLog sends output to the console NSLog(@"Hello World!"); } @end


Objec+ve C / Hello World

•  Main.m #import <Founda+on/Founda+on.h> #import "HelloWorld.h"

int main (int argc, const char * argv[]) {

HelloWorld *myHW = [[HelloWorld alloc] init];

// Most common view [myHW printHelloWorld];

// ObjC 2.0+ myHW.printHelloWorld;

[myHW release];

return 0; }

•  Terminal Build [majer@chimera:hw/] gcc ‐o hello ‐framework Founda+on ‐lobjc main.m HelloWorld.m

•  Output 2009‐04‐26 11:07:26.005 hello[29012:807] Hello World! 2009‐04‐26 11:07:26.007 hello[29012:807] Hello World!


iPhone Development Model

•  iPhone uses Model View Controller paqern – Model: all data related func+onality

– View: all UI related func+onality – Controller: all classes required to for applica+on func+onality •  interacts with the other two.

•  Nothing prevents programmer from viola+ng the paqern


MVC Paqern •  Model/Data

–  Classes that hold and/or manipulate the data used by the applica+on •  Card, CardDeck, AppConfig

–  I primarily developed outside of Xcode using vim and a shell prompt •  Vim chosen only because of familiarity •  Was trying to ease into ObjC and basically performing a 1:1 C++‐>ObjC

transla+on •  This means I manually wrote my geqers/seqers

–  Thoroughly tested my classes prior to any Xcode/iPhone sdk work began •  Unit tes+ng on data model classes performed outside of Xcode environment

–  Custom driver that was built using standard gcc/make and run from a shell prompt •  Want to ensure that any issues encountered were not caused by issues from

Data Model but were new in the UI code or the Controller code •  Try to eliminate as many variables as possible to make debugging easier


MVC Paqern

•  View –  Classes that manipulate the UI of the applica+on

•  Created en+rely in Interface Builder, output is a large xml file which, while editable, is difficult to work with. –  Drag and drop arrangements of buqons/textboxes/etc. –  Items added to view are associated with variables in the controller code also by drag and drop.

•  Can be done by hand, almost required to be done by hand for sufficiently complex applica+ons. –  Look at ConvertBot for an example of an advanced UI

•  3 Views in my app, Review, Quiz, and Setup


MVC Paqern

•  Controller – The actual applica+on func+onality. –  Interacts with the outlets created in the View –  Interacts with the data classes. – Typically 1 controller per view, there were 3 views and 3 controllers in my applica+on. •  ReviewViewController •  SetupViewController •  QuizViewController


Quick Demo Time Permi>ng

•  Xcode Build – HelloWorld •  Xcode Build – Flashcard App •  Xcode ‐> Simulator – Flashcard App

•  Xcode ‐> iPhone – Flashcard App •  Xcode Build – Bubble Level


Resources •  hqp://developer.apple.com

–  Single biggest asset, ar+cle, sample code, etc –  Accessible post registra+on/payment

•  Online communi+es – (Yahoo|Google) groups –  macsb, iphonesb, iphonesdk, iphonesdkdev –  High volume mailing lists, good for lurking and searching through

•  Programming in Objec+ve‐C –  Stephen G Kochan / Developer’s Library

•  Good for concepts, however get the 2nd Edi+on, the first has fundamental errors

•  Cocoa with Objec+ve‐C –  James Davidson & Apple Computer Inc / O’Reilly –  Not iPhone specific, geared towards OSX but mostly applicable –  Covers MVC and how it applies in reasonable detail

•  Beginning iPhone Development –  Mark LaMarche / Apress –  Good starter book, uses UI Builder

•  iPhone SDK Applica+on Development –  Jonathan Zdziarski / O’Reilly

•  The iPhone Developer’s Cookbook –  Erica Sadun / Addison Wesley


The First App

From Concept to Reality

The First App

•  The Idea –  Build something you personally need or will use regularly, there’s a good chance someone else will benefit from it •  My app created to help me memorize calculus formulas.

•  I was the sole/intended customer

– Work with some friends to come up with ideas, everyone has them •  Don’t be terribly concerned about “protec+ng your idea” •  An idea is nothing without solid execu+on


The First App

•  The Idea – Try to avoid games for the first app if you haven’t already wriqen them on a Mac before •  Amazingly compe++ve

•  Higher download counts required to stay on ranking lists

•  Bypasses UIBuilder in favor of OpenGL or Quartz •  Caveat: Games have the highest upside poten6al in sales


The First App •  Mone+za+on Models

–  Apps are either created with the intent to be free, or with the hope to generate revenue

–  Free apps •  2 flavors

–  Truly free, download and use, 0 profit for author –  Ad driven, download and deal with ads, author gets ad revenue

»  AdMob, VideoEgg

–  Lite apps •  Fully func+onal apps that may not have as many features as the “full” version

–  Every feature in a Lite app must work –  Can’t have grayed out func+onality –  Typically offered as free or inexpensive apps to en+ce buyer

–  Pay apps •  Fully func+onal apps

–  Priced from $.99 (thousands) to $999.99 (1 app called “Am I Rich” which allegedly sold 5 copies)


The First App

•  The App Store – iTunes – One stop shopping for the i{Pod,Phone} experience. •  Es+mated Touch plaporm user base for EOY 2009 @ 50M devices worldwide

– Applica+ons sold along side music and videos – Centralized billing – Sole distribu+on mechanism for legal iPhone applica+ons





The First App

•  App Store Problems – Visibility

•  There are 20k+ apps in the store through which you must wade to find your app

•  Hard to search, clunky interface •  Ra+ng system issues

–  Hard to contest 1 star reviews or people with grudges –  Only recently did a user have to have purchased the app to review it

–  Too easy to create throwaway account to buy an app to write a scathing review


The First App

•  App Store Problems – Ra+ng Systems

•  Top X Lists –  It is cri+cal to stay on those lists to keep the traffic coming –  Dropping off the list results in applica+ons being found either by paging or by specific searches »  Do you want to page through 20k apps?

•  New submissions –  Any submission regardless if it’s the ini+al 1.0 submission or the 43rd update are considered new apps on the store

–  People game the new app spots by releasing point versions frequently with minor changes


The First App

•  Determine Marke+ng Strategy – Can be accomplished by issuing demo licenses/keys to review sites

– Adver+sing on ad networks – Press releases – Plan to market your product if you hope to generate revenue from it •  Make friends with students in the marke+ng department


The First App •  Market Research

–  Look for compe++on •  Not having compe++on any may not be a good thing

–  Market could be too small for a single applica+on •  There are typically 10 variants on a theme in the app store

–  Compe++on != undoable. –  Buy the compe+tor apps, dissect them, compare features –  Try to build a wining feature set from the other products

•  Pay aqen+on to compe+tor pricing to es+mate release price. –  99c is not a sustainable price point. –  Most apps cost less than a Starbucks Laqe, people will pay that much for an app. –  Don’t forget Apple keeps 30%

•  My App •  Many flashcard apps, fewer with quizzing ability •  Several Calculus formula reference apps •  No intersec+on apps that I could find


The First App

•  Determine Feature Set –  Remember: You will most likely be working alone

•  There are a finite number of hours in aday and you will need to eat/sleep/go to class

–  Based on your market research and mone+za+on model, determine which features would be cri+cal path for 1.0 release and/or the Lite release.

–  Take the features that you s+ll want to keep that didn’t make it into 1.0 and plan the 1.1 release at the same +me.

•  My App •  I knew what I wanted, calculus formulas with the integrals/deriva+ves on the back to aid in memorizing and a quizzer func+onality

•  Flexibility to swap out my datasets for things my 3 year old daughter could use

•  Prof Fleck added a few to make things more challenging/interes+ng


The First App

•  Create a Project Plan –  Open Project freely available –  Es+mate the +me needed to complete desired features for each version planned.

–  Double your +me es+mates on first version(s). •  At the start of the semester mine were off by as much as 2x as I learned the environment. 3 months later I was much more accurate and could approximate in hours how long things would take me.

•  My App •  I started on OpenProj then migrated to MS Project •  The project plan gave me a guide to where I should be overall •  I didn’t always add features in the order they were listed on the plan



The First App

•  Build your corporate/developer Website –  Consider building a development blog

•  Can be used as a marke+ng tool, a source of beta customers, and a support mechanism

– Open v Closed •  Several μISVs have started pos+ng full sales figures and development info to their customers. –  Transparency gives customers a warm fuzzy. –  Inspiring to other developers as well.

•  My app •  I have a personal website that I added a bit of func+onality for the card update and phone home features, but otherwise haven’t made it to a real blog/website for the app


The First App hqp://www.kalzumeus.com/ ‐ Developer/Personal hqp://www.bingocardcreator.com/ ‐ Corporate


The First App hqp://www.seoxys.com/ ‐ Developer/Personal

hqp://excesapp.com/ ‐ Corporate


The First App

•  Setup a Bug Tracking Database – Many of them out there, pick a free one –  Load it with all of the features that you’ve just outlined in your project plan •  Mark them closed as you implement the features

– Get in the habit of using it. •  I tracked features, real bugs, and ideas •  You will eventually have customer reported bugs to put in it

•  My App •  I originally used any piece of paper on my desk •  I copied the notes from about 5 envelopes into an excel spreadsheet which I then used for the rest of the process



The First App

•  Setup a Source Control Repository – Xcode integrates with SVN and several others

•  Configure it and get in the habit of using it. – Commit regularly, especially before making large changes to the codebase.

–  I’m using both TimeMachine to back up the MBP as well as SVN for my source.


The First App

•  Develop App (Finally!) –  S+ck to the feature list on the plan

•  Feel free to push features to next version •  Try not to add anything new (beware feature creep)

–  Retain those new features in your tracking soaware –  Refactor code regularly –  Test in Simulator –  Test on iPhone –  Test on iPod Touch –  Consider joining the online communi+es

•  macsb, iphonesdk, iphonesdkdev, iphonesb – Make friends with some graphic designers

•  You’ll need icons and a general look/feel


The First App

•  Developing my app •  I have on average 1‐2 hours a night and 8‐12 hours on the weekend for over+me/school work/down+me

•  When I was home, I worked on average 2‐3 nights a week and at least one weekend day

•  First light was aaer 50ish hours across several weeks –  Review worked, basic skeleton for Setup screen, Quiz screen would

register buqon presses –  That +me wasn’t all coding on my app, there was a substan+al amount of

reading/research/other coding involved •  At the next checkpoint the vast majority of features were complete

–  All views worked, and the more advanced features were then addressed »  Phone home, downloading decks from net, displaying images

(needed for calculus formulas), etc •  App is basically feature complete at this +me

–  A few things I would do differently based on knowledge I now possess


The First App

•  Tes+ng –  Xcode seems a bit lacking in this regard – My tes+ng was done outside of the Xcode environment from the terminal prompt using standalone drivers

– Didn’t find way to automa+cally test UI •  I used family members as testers and observed their use •  Firms offer hourly testers to development groups

–  Should also consider a method for nightly builds and/or nightly tests and/or automa+c builds.


The First App

•  Beta Tes+ng –  You’ve made it this far, congrats! –  Each developer has ~100 devices he can add as development devices

–  If you have the blog, send out a request for beta testers

–  If you joined the communi+es, ask there. –  Find friends/family with devices that can help. –  Try to avoid a release without some sort of beta test. – Make sure you test on both the iPod and the iPhone


The First App •  Retooling/Refactoring

–  Since you have all this beta tes+ng data you can now go back and review it •  Address Missing features •  Fix UI Kludginess •  Fix the bugs the first user found on his first use

–  Prof Fleck found an issue in my app the very first use, he tried an edge case I didn’t think of because I was too familiar with the app.

–  Reiterate the beta as many +mes as you need to get it close to being “shippable” •  Realize that “shippable” is a moving target that has many different defini+ons

•  My app •  Aaer watching my niece and nephew use the app, I realized that the swiping wasn’t

intui+ve to someone unfamiliar with the plaporm –  They kept trying to push the arrows at the boqom of the display

•  Aaer taking a basic math quiz my nephew (grade 4) then asked “Which ones did I get wrong?” –  Enumera+ng wrong answers wasn’t in my ini+al use case as it just didn’t occur to me.

•  He also pointed out that I made an error on ’12 + 1 == 11’


The First App •  Submit to App Store

–  Perhaps the single most frustra+ng part of process –  There are no official submission guidelines. –  There are also no official developer guidelines sta+ng what is and isn’t

acceptable. –  This can take as liqle as 1 week up to several months. –  Make sure you’ve tested on both the iPhone and the iPod Touch. –  You’re basically at Apple’s whim.

•  My App •  While I intend on submi>ng the app eventually, I will not be submi>ng the

app as it currently stands. •  Change Orienta+on •  Find a way to integrate MathML to bypass crea+ng image cards for every

formula •  Hire a designer to make it pre>er


The First App

•  Ge>ng an App Rejected –  Topics fairly certain to get rejected:

•  Obsceni+es •  Adult Content •  Drugs •  Duplica+ng func+onality of exis+ng apps

–  Podcast streaming, mail clients, browsers, etc –  Being loosened slightly

–  Apple is also not consistent in what it approves •  Flashlight apps were ok, then pulled, now possibly ok again •  iBaby was originally approved, then rejected •  A twiqer client was rejected because of the poten+al for adult language.

•  Apple claims func+onality is the determining factor yet approves the iFart line of apps


The First App

•  Support – Congrats on your success! – Now you can look forward to:

•  Responding to user emails

•  Fixing bugs •  Adding user requested features

–  You are s+cking to your release plan, right? •  Resubmi>ng your app to App Store for acceptance

– Lather, rinse, repeat.


The First App

•  Endgame – Collect your earnings from Apple

•  They take their 30% off the top. – Start planning the next version of the exis+ng app or the next new app.

– Alterna+vely decide that you’re done coding on the iTouch plaporm and go code in Java for Android.

– Re+re – Or in my case, start memorizing



Ques+ons?
