Secrets of an iPhone Developer

Brian RobbinsFounder, Riptide Games

Slides at http://www.dubane.com/cons/

FITC Mobile – September 14, 2009

Today• Programming

– AudioSession– Accelerometer Input– Accelerometer Calibration– Prevent screen darkening– OS 3.0/2.0 compatibility– Anti-Hacking– NSZombieEnabled– Xcode 3.2 Errors / Warnings– Xcode 3.2 Static Analyzer– Demo

• App Development– Provisioning Profile tips– iTunes Connect– App Submission Tips– Analytics tracking– Score / Networking Tools– iPhone Configuration Utility (iPCU)– Other Useful Tools

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

Today’s Goal

Most useful session you attend

Sept 14, 2009 Brian Robbins - slides available: http://www.dubane.com/cons/

Programming

AudioSession

• Can use AudioSession APIs– C-based

• Or AVAudioSession (SDK 3.0)– Obj-C wrapper into same C calls

• Categories:– Ambient – Games, allows background iPod

Music Playback and follows ringer switch– SoloAmbient – Same as ambient, but stops iPod

Music Playback so use this if you have your own background music

– Playback – Use for audio playback apps– Record & PlayAndRecord – For recording and

playback

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

Accelerometer Input• Use an adaptive Low-Pass filter, for better response• Full Implementation in the AccelerometerGraph sample

application

#define FILTERFACTOR 0.1#define ATTENUATION 3.0#define MINSTEP 0.02

// Start with the value from a basic low-pass filterbasevalue = (newAcceleration * FILTERFACTOR) + (previousValue * (1.0 -

FILTERFACTOR)); // Smooth more for small movement to filter out noised =

Clamp(ABS(Normalize(basevalue)-Normalize(newAcceleration))/MINSTEP - 1., 0., 1.);

// Calculate a proportional factoralpha = (1.-d) * FILTERFACTOR / ATTENUATION + d * FILTERFACTOR;// Use the new factor to offset smoothed valuesvalue = newAcceleration * alpha + basevalue * (1. - alpha);

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

Accelerometer Calibration

• Map to the user’s starting orientation when doing heavy accelerometer control

• Do this when action starts, and ideally tell the user

• Sorry (James) no example

Sept 14, 2009 Brian Robbins - slides available: http://www.dubane.com/cons/

Prevent Screen Darkening

• Turn on during gameplay• Turn off in menus

[UIApplication sharedApplication].idleTimerDisabled = YES;

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

OS 3.0 / 2.0 compatibility

• Use OS 3.0 features like MPMusicPicker, without requiring OS 3.0–Why? OS upgrades on iPod Touch is very

low

• 4 technical steps• Business rules for behavior

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

OS 3.0 / 2.0 Compatibility

1. Target > Info > General– Set Framework Linked Library from

“Required” to “Weak”

2. Target > Info > Build– Set Base SDK to latest SDK (ie 3.0)

3. Target > Info > Build– Set iPhone OS Deployment Target to oldest

SDK (ie 2.1)

4. Check for availability of class before using it– if ([MPMusicPickerController])

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

Anti-Hacking

• http://thwart-ipa-cracks.blogspot.com/• Very simple detection, can go a lot

more complexNSBundle *bundle = [NSBundle mainBundle];NSDictionary *info = [bundle infoDictionary];if ([info objectForKey: @"SignerIdentity"] != nil){

/* do something */}

• Can also look to see if app is encrypted, check size of info.plist, call home, etc.

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

NSZombieEnabled

• Executables > Info > Arguments– NSZombieEnabled value YES

• Good for EXC_BAD_ACCESS• BAD for memory!!!

Sept 14, 2009 Brian Robbins - slides available: http://www.dubane.com/cons/

Xcode 3.2 Errors & Warnings

• Use the tabs to see from last build or all builds

• Can also group by type instead of by class

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

Xcode 3.2 Static Analyzer

• Uses Open Source Clang analyzer• Good for memory references and

Obj-C coding compliance• Freaking awesome!

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

Live Demo

Sept 14, 2009 Brian Robbins - slides available: http://www.dubane.com/cons/

App Development

Provisioning Profile Tips

• Make and use a single “wildcard” App ID– Nothing but a single *– Use that for all development and

provisioning profiles– Unless you’re doing in-app purchase or

Push Notification• When adding devices or users make

a new Provisioning Profile– ie Riptide_Dev_01, Riptide_Dev_02

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

iTunes Connect

• Release Date–When submit, set it to whatever, probably

1-2 weeks in the future– The moment you get approval set the

release date to today– For Updates, leave release date as is

when submit• Setting to future will remove you from store!

–Moment approved, set release date to today

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

iTunes Connect App Submission

• Taking ~2 weeks for approval– Every time, even if rejected for app

description problem!

• Plan for keywords, but don’t use competitor names

• Don’t put pricing in your app description

• Don’t put keywords in your app title

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

Analytics Tracking

• Simple, cheap (free) and very easy to implement

• PinchMedia is good• Other major one is Flurry Analytics• Not something you need to pay for!

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

Score / Networking

• Good idea, especially for games• Use an existing network to borrow

traffic/users• OpenFeint, ScoreLoop are biggest

open ones• Plus+ from ngMoCo is picking up

steam, but you have to talk to ngMoCo to use it.

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

iPhone Configuration Utility

• Search for iPhone Configuration Utility on Apple Site (2.1 latest version)

• Basically the Xcode Organizer without Xcode

• Much easier for AdHoc users to install and manage apps

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

Other Useful Tools

• MajicRank– http://www.majicjungle.com/

majicrank.html

• AppViz– http://www.ideaswarm.com/

• MobClix for rank tracking– http://www.mobclix.com/appstore/1

• AppShopper for price history– http://appshopper.com/

Sept 14, 2009 Brian Robbins - slides available: http://www.dubane.com/cons/

Recap• Programming

– AudioSession– Accelerometer Input– Accelerometer Calibration– Prevent screen darkening– OS 3.0/2.0 compatibility– Anti-Hacking– NSZombieEnabled– Xcode 3.2 Errors / Warnings– Xcode 3.2 Static Analyzer– Demo

• App Development– Provisioning Profile tips– iTunes Connect– App Submission Tips– Analytics tracking– Score / Networking Tools– iPhone Configuration Utility (iPCU)– Other Useful Tools

Brian Robbins - slides available: http://www.dubane.com/cons/ Sept 14, 2009

Questions?Slides at

http://www.dubane.com/cons/

Brian Robbinswww.riptidegames.com

Twitter: @dubanebrian@riptidegames.com