Ten Commandments for iPhone Software Development Adrian - - PowerPoint PPT Presentation

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Ten Commandments for iPhone Software Development Adrian - - PowerPoint PPT Presentation

Dec 05, 2023 135 likes •1.85k views

Ten Commandments for iPhone Software Development Adrian Kosmaczewski akosma software akosma.com github.com/akosma linkedin.com/in/akosma formspring.me/akosma twitter.com/akosma slideshare.com/akosma Some questions Who s new to iOS?

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Ten Commandments

for iPhone Software Development

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Adrian Kosmaczewski

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akosma software

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akosma.com github.com/akosma linkedin.com/in/akosma formspring.me/akosma twitter.com/akosma slideshare.com/akosma

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Some questions

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Whoʼs new to iOS?

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Which technologies?

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J2EE J2ME .NET Ruby / Rails

  • thers?
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Which programming languages?

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C / C++? Java, C#? Ruby, Python, Lua? JavaScript? Fortran, Lisp, COBOL?

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10 Commandments

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SLIDE 15 http://www.flickr.com/photos/oseillo/345879263/
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SLIDE 16 http://www.flickr.com/photos/justdrew1985/4348527596/
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1

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Thou shalt manage memory properly

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SLIDE 20 http://www.flickr.com/photos/blakespot/3030107382/
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  • iPhone 3G: 128 MB RAM
  • iPhone 3GS, iPad: 256 MB RAM
  • iPhone 4: 512 MB RAM
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±70 MB for the OS!

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no swap file

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(no virtual memory)

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SLIDE 25 http://www.flickr.com/photos/cheek/699407283/
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no garbage collection

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  • bjects have a

“retain count”

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SLIDE 28 http://cocoadevcentral.com/d/learn_objectivec/
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basic rule:

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for every [alloc], [retain], [copy] there must be a [release]

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beware:

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Objective-C only allows

  • bjects on the heap
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SLIDE 33 http://linguiniontheceiling.blogspot.com/2008/10/thats-madame-trash-heap-to-you.html
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No automatic objects

  • n the stack (C++)
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SLIDE 35 http://www.futuregov.net/photologue/photo/2008/aug/30/stack-papers/
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// C++ // Memory freed when out of scope std::string name(“Adrian”); std::string *name = NULL; name = new std::string(“Adrian”); delete name;

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iPhone OS memory warnings

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SLIDE 39 http://www.flickr.com/photos/tbuser/2763035540/
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SLIDE 40 http://akosma.com/2009/01/28/10-iphone-memory-management-tips/
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2

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Thou shalt remove all compiler warnings

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GCC_TREAT_WARNINGS_AS_ERRORS

  • Werror
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Why Warnings?

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  • Using deprecated symbols;
  • Calling method names not declared in included headers;
  • Calling methods belonging to implicit protocols;
  • Forgetting to return a result in methods not returning “void”;
  • Forgetting to #import the header file of a class declared as a

forward “@class”;

  • Downcasting values and pointers implicitly.
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Solutions

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Make your intentions explicit to the compiler

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  • Make implicit protocols explicit
  • Create categories for private methods
  • Turn implicit type conversions and casts into

explicit ones

  • Use @class in the @interface, #import on the

@implementation

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SLIDE 53 http://akosma.com/2009/07/16/objective-c-compiler-warnings/
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3

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Honor the Human Interface Guidelines

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http://developer.apple.com/iphone/ library/documentation/ userexperience/conceptual/ mobilehig/

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Your Objective:

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avoid rejections

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SLIDE 63 http://flyosity.com/application-design/iphone-application-design-patterns.php
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SLIDE 64 http://www.smashingmagazine.com/2009/07/21/iphone-apps-design- mistakes-overblown-visuals/
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SLIDE 65 http://www.mobileorchard.com/avoiding-iphone-app-rejection-from-apple/
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SLIDE 66 http://www.apprejected.com/
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SLIDE 67 http://appreview.tumblr.com/
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SLIDE 68 http://kosmaczewski.net/2009/08/03/risk-management-in-iphone-projects/
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Your Objective:

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avoid this

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SLIDE 71 http://www.flickr.com/photos/gruber/2635257578/
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and this

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SLIDE 73 http://smokingapples.com/iphone/app-store-iphone/the-worst-twitter-client-ever/
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” “

I canʼt find one redeeming quality about this app. Itʼs slow to start [on a 3GS], doesnʼt respond to taps while itʼs trying to load other things, and crashes if you try to change modes a lot. Itʼs limited to only timeline, replies, and messages. It has no other functionality. Oh wait… I forgot its killer feature, you can have custom backgrounds and choose the color of your tweets. That totally makes up for its lack of useful features and sluggish performance. Iʼm not sure why someone would bother building such an inferior app other than that they wanted to find some suckers and score a quick buck. It seems even more insane to me that theyʼd be actively seeking out reviewers to cover this. I was given a promo code for ChillTwit, and even for free I didnʼt want it on my phone. I was sad just from looking at

  • screenshots. Actually seeing it running confirmed all of my fears. If it was a free

app, I might forgive the developer, but the fact that heʼs trying to get $0.99 out of people pisses me off to no end. Go buy Tweetie. If you somehow werenʼt scared away by all my bitching and whinning, you can see ChillTwit on the app store here. But seriously, if you buy this, weʼre not friends anymore.

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4

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Thou shalt optimize for performance

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  • Drawing and scrolling
  • Application launch
  • Files and data
  • Power and battery life
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Drawing and scrolling

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  • UIView subclasses are already optimized
  • Custom views should use

setNeedsDisplayInRect: whenever possible

  • Cache static objects
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  • Use opaque views
  • Avoid allocating while scrolling
  • Reuse table cells
  • Collapse view hierarchies
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Application Launch

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  • Design apps for quick launch and short use
  • Load data lazily
  • Load only images needed
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Files and Data

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  • Use Core Data for large datasets
  • Avoid loading large files in memory
  • Use plist files for structured static data
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Power management

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  • 3G communications are expensive
  • Wi-Fi slightly cheaper
  • Send small chunks of data at low frequency
  • Prefer “chunky” to “chatty” protocols
  • Better performance ==

longer battery life

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5

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Thou shalt test in the device

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SLIDE 91 http://blogs.tech-recipes.com/itouchmyiphone/2008/03/26/from-iphone-sdk-to-simple- app-in-less-than-452-seconds/
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SLIDE 92 http://www.flickr.com/photos/edans/1526393678/
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  • Camera
  • Accelerometer
  • GPS
  • Compass
  • Battery
  • Network
  • ... Speed!
http://www.flickr.com/photos/tensafefrogs/728581345/
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SLIDE 94 http://www.flickr.com/photos/schill/969088410/
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SLIDE 95 http://www.flickr.com/photos/jaytamboli/3788327603/
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Keep your old 3G(S)

  • r iPod touches!
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6

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Remember your developer tools

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Shark

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Instruments

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7

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Thou shalt use PNG files

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Portable Network Graphics (PNG) is a bitmapped image format that employs lossless data compression. PNG was created to improve upon and replace GIF (Graphics Interchange Format) as an image-file format not requiring a patent license. It is pronounced /ˈpɪŋ/ [1] or spelled out as P-N-G. The PNG acronym is optionally recursive, unofficially standing for “PNG's Not GIF”.[2]

http://en.wikipedia.org/wiki/Portable_Network_Graphics
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Advantages

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Compression on build

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Low memory footprint

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Supported by all editors

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Quality

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SLIDE 118 http://en.wikipedia.org/wiki/File:Comparison_of_JPEG_and_PNG.png
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Transparency

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SLIDE 120 http://en.wikipedia.org/wiki/Portable_Network_Graphics
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  • App icon: 57x57

“Icon.png”

  • Default image: 480x320

“Default.png”

  • Settings icon: 29x29

“Icon-Small.png”

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App Icon

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Design in maximum quality, then reduce

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Do not apply effects

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SLIDE 125 http://developer.apple.com/iphone/library/documentation/userexperience/conceptual/mobilehig/
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512x512 72 DPI TIFF file for App Store

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8

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Thou shalt use static analysis

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SLIDE 130 http://llvm.org/
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SLIDE 131 http://clang-analyzer.llvm.org/
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SLIDE 133 Source: Apple Documentation
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SLIDE 134 Source: Apple Documentation
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SLIDE 135 Source: Apple Documentation
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SLIDE 136 Source: Apple Documentation
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9

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Thou shalt care about accessibility

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Setting the “name” property in Interface Builder makes widgets accessible

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simple

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and thereʼs no reason not to do it.

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call to action!

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Add accessibility information to your apps now!

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10

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Thou shalt have project management hygiene

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  • Project management
  • Human resource management
  • Developer working conditions
  • Prototypes
  • Quality management
  • Code organization
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SLIDE 150 http://kosmaczewski.net/2009/07/28/code-organization-in-xcode-projects/
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Your objective:

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avoid chaos

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SLIDE 153 http://www1.standishgroup.com/newsroom/chaos_2009.php
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SLIDE 154 http://www.geekonomicsbook.com/
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11

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Thou shalt have fun!

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and

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be creative!

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Recapʼ

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1. Manage memory properly 2. Remove compiler warnings 3. Read the Human Interface Guidelines 4. Optimize for performance 5. Test in the device

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6. Know your developer tools 7. Use PNG files 8. Use static analysis 9. Care about accessibility

  • 10. Have project management hygiene
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  • 11. Have fun and be creative!
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Thanks!

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Slides available in

slideshare.net/akosma

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Questions?

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Ces slides sont disponibles avec une licence Creative Commons Attribution-No Derivative Works 3.0 Unported License http://creativecommons.org/licenses/by-nd/3.0/