Between Cocoa and Cocoa Touch: A Comparative Introduction

Between Cocoa and Cocoa Touch: A Comparative Intro lukhnos Lithoglyph Inc. 2009-01-22

Topics Covered •3 Essential Facts • History • What’s in Common • What’s Different • Migration Paths

Three Essential Facts

• Cocoa and Objective-C go together • You need to know Foundation (NS.+) classes • App Store on iPhone is the disruptive technology

History

NEXTSTEP 1989-1995 Mach, Objective-C The “NS-” preﬁx

Mac OS X 1999-present BSD userland Quartz Carbon Cocoa

iPhone OS 2007 OS X under hood Desktop-grade services

What’s in Common

• Main Development Language • OS and Framework • Design • Tools

Main Developement Language • Objective-C • Child of Smalltalk, sibling of Ruby • “C with OO” • Also, Objective-C++

OS and Framework • Mac OS X essentials • BSD userland • CoreFoundation • Quartz • Foundation • Core.+ system components

CoreFoundation • C, refcount-based data type and system service library • CFTypeRef family: array, dictionary, date, number, string... • Runloop management, i18n, etc. • CFNetwork stack • Quartz and other Core.+ services share the same model

Foundation • The basis of Cocoa (hence “Foundation”) • All beginning with “NS” preﬁx (for historical reasons) • Non-nil containers: NSArray, NSDictionary, NSSet etc. • NSRunLoop, NSThread, etc., high-level system services • NSUserDefaults, NSNotiﬁcationCenter, app-support infrastructure

Design • Bundle • Internationalization • Design patterns • delegate • notiﬁcation • target/action model

Tools • gcc • Xcode • Interface Builder • Instrument

What’s Different?

• Device Characteristics • System Limitations • SDK Differences • Development Limitations

Device Characteristics • Screen estate • Nature of events • Usage, context, depth v.s. shallowness • Connectivity/ubiquitity

System Limitations • Memory footprint • App lifecycle • Sandbox • No inter-app communication

SDK Differences • AppKit v.s. UIKit • NSWindow/NSView v.s. uniﬁed UIView model • Better, re-inforced MVC paradigm in iPhone SDK

Development Limitations • No external framework • No automatical garbage collection (GC) ! • Sandbox • Code signing constraints • Testing and distribution constraints

Some Things We’ve Learned

• Think in Objective-C 2.0 • Different platform for different use • Maximize shared code base, sweat on platform details

Think in Objective-C 2.0 • @property saves your poor ﬁngers • Fast enumeration also rocks • Formal and optional protocol can lead to better design • Also, in Cocoa, performSelector:onThread: etc. makes life easier

Different Platform and Use • “Your iPhone is not a Mac Pro” • Think in bigger picture: Mobile-Web-Desktop integration

Shared Code Base? • Cross-platform way of thinking helpful • Thinkin 32/64-bit neutral code, Endian-agnostic, encoding- agnostic, etc.

In Essence • Objective-C is a must • Know the shared libraries: Foundation, CoreFoundation • Sweat the minor differences and details

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Between Cocoa and Cocoa Touch: A Comparative Introduction

by lukhnos on Apr 21, 2009

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Between Cocoa and Cocoa Touch: A Comparative Introduction — Presentation Transcript