High quality iOS development

High Quality iOS Development

@robinluIN-SRC Studio

Saturday, April 9, 2011

Quality


Topics

• Memory management

• Tools

• Crash Reports

• Test


Memory Management


Memory Management

alloccopyretain

objectreference

countrelease

+1 -1

0

dealloc


OwnershipDeclare ownership

• create / copy

• instance variable

• container

• multi-thread

• ...

Release ownership

• don’t need anymore

• dealloc of owner


Autorelease

• give the ownership to autorelease pool

• default autorelease pool created by AppKit

• life cycle = event cycle

• You can create your own autorelease pool

• Don’t over use autorelease


Problems

• Memory Leak

• Over-release


RulesYou only release or autorelease

objects you own

• If you own the object by alloc, copy or retain, you have to release or autorelease

• If the object is not owned by you, don’t call release or autorelease


Pitfalls

• Implicit Onwership

• Circular Reference


Implicit Ownership

• NSTimer

• Delayed performance of selector

• Thread

• IBOutlet


Circular Reference

A retains B

B retains C

C retains A

A

C B

Break it with weak references


General Practices

• Instance Variables

• Local Variables


Instance Variable

get ownership in release ownership in

init dealloc

viewDidLoadviewDidUnload

dealloc

settersetterdealloc


Local Variable

Always release or autorelease in the same scope


Summary

• Ownership

• Rules

• Pitfalls

• Practices


Analyze


Analyze

• Clang Static Analyzer

• More powerful than compiler warnings

• Bug finder

• memory leaks

• dead store

• logic error

• ...


Memory Leaks


Potential Memory Leak


Dead Store

Value stored to ‘matchedRange’ during initialization is never read


Logic error


Run Analyze


Instruments


Instruments

• Memory

• Performance

• ...


Memory

• Memory Leaks

• Abnormal Allocation

• Heapshots

• Over Release

• Zombies

• Memory Clean up

• VM Tracker


Time Profiling

• Sampling

• Record Mode

• Immediate mode

• Deferred mode


Crash Reports


Crash Reports

• What’s crash reports?

• Where to get crash reports?

• How to read crash reports?

• Generate crash reports by 3rd party lib


Xcode Organizer

Get crash reports from devices


Local Directories• Mac OS X: ~/Library/Logs/CrashReporter/

MobileDevice/ <DEVICE_NAME>

• Windows XP: C:\Documents and Settings\<USERNAME>\Application Data\Apple Computer\Logs\CrashReporter\MobileDevice \<DEVICE_NAME>

• Windows Vista + 7: C:\Users\<USERNAME>\AppData\Roaming\Apple Computer\Logs\CrashReporter\MobileDevice\<DEVICE_NAME>


iTunes Connect

Get users’ crash reports after release


Crash Types

• EXC_BAD_ACCESS (SIGBUS or SIGSEGV)

• EXC_CRASH (SIGABRT)

• Low Memory

• 00000020

Exception Codes Type

0x8badf00d Timeout

0xdeadfa11 User Force-Quit


Symbols

• Keep symbol before each release

• Xcode Archive

• dSYM file

• Read the report

• Xcode organizer

• atos, symbolicatecrash, symbolizecrashlog

• 3rd party tools - Symbolicator


Test


Test

• Unit Test

• Beta Test

• Automating UI Test


Unit Test

• Unit Test Target

• How easy to test: M > C > V


Automating UI Test

• Instruments

• Accessibility

• Javascript


Beta Test

• Ad Hoc

• Build suggestion:

Ad Hoc and Distribution share the same bundle id but different from Debug build


Ad Hoc Deploy

• Deploy via internet

• Hockey

• TestFlightApp.com

• dropbox


Crash Report Lib

• plcrashreporter

• http://code.google.com/p/plcrashreporter/

• can be used in both ad hoc and distribution builds

• output as protobuf-encoded messages


http://code.google.com/p/plcrashreporter/

http://code.google.com/p/plcrashreporter/

Thanks!


High quality iOS development

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