Objective-C

오브젝티브-C (Objective-C, 종종 ObjC로 표기) 언어는 C 프로그래밍 언어에 스몰토크 스타일의 메시지 구문을 추가한 객체 지향 언어이다.

현재, 이 언어는 애플의 매킨토시의 운영 체제인 맥 오에스 텐과 아이폰의 운영 체제인 iOS에서 사용되고 있다. 오브젝티브-C는 애플의 코코아를 사용하기 위한 기본 언어이며, 원래는 넥스트의 NeXTSTEP 운영 체제에서 주 언어였다. 일반적인(Generic) 오브젝티브-C는 앞에서 언급한 라이브러리를 사용하지 않는다.

Basic

• (펌) Objective C의 기본 문법
• ObjectiveC:DefaultClassTemplate: Objective-C 기본 클래스 작성 방법.
• XCode
• XCode:iPhone:Basic - iPhone 앱 개발 기초.
• iOS
• Core MIDI - Communicate with MIDI devices such as hardware keyboards and synthesizers.
• Core Audio
• Apple

List of Objective-C 2.0 @ Compiler Directives

• @class
• @defs
• @protocol @required @optional @end
• @interface @public @package @protected @private @property @end
• @implementation @synthesize @dynamic @end
• @throw @try @catch @finally
• @synchronized @autoreleasepool
• @selector @encode
• @compatibility_alias
• @"string"

CMake compile

• Stackoverflow - CMakeLists.txt for an Objective C Project

clang을 사용할 경우 아래와 같이 objective-c를 컴파일 할 수 있다.

cmake_minimum_required(VERSION 2.8)
project(HelloWorld)
set(NAME HelloWorld) 
set(CMAKE_C_FLAGS "-x objective-c")
#set(CMAKE_CXX_FLAGS "-x objective-c++")

set(HEADER_FILES 
    ./uhdplayerengine/HelloWorld/HelloWorld/AppDelegate.h
)
set(SOURCE_FILES 
    ./uhdplayerengine/HelloWorld/HelloWorld/AppDelegate.m
    ./uhdplayerengine/HelloWorld/HelloWorld/main.m
)
set(XIB_FILE
    ./uhdplayerengine/HelloWorld/HelloWorld/Base.lproj/MainMenu.xib
)

add_executable(
    ${NAME}
    MACOSX_BUNDLE
    ${HEADER_FILES}
    ${SOURCE_FILES}
    ${XIB_FILE}
)

set_source_files_properties(
    ${XIB_FILE}
    PROPERTIES
    MACOSX_PACKAGE_LOCATION
    Resources
)

set_target_properties(
    ${NAME}
    PROPERTIES
    MACOSX_BUNDLE_INFO_PLIST
    ./uhdplayerengine/HelloWorld/HelloWorld/HelloWorld-Info.plist
)

target_link_libraries(${NAME}
    "-framework Cocoa"
    "-framework AppKit"
    "-framework CoreData"
    "-framework Foundation"
)

Linker플래그를 전달 할 때 Foundation을 -lFoundation으로 인식할 경우 -Wl,-framework,Foundation과 같이 전달하면 된다.

Framework

• Foundation
• AVFoundation
• CoreVideo
• CoreMedia
• CoreGraphics
• OpenGL
• CoreImage
• AppKit
• CoreFoundation
• Security
• AudioToolbox
• VideoToolbox
• CoreServices
• CGDirectDisplay

Memory management

Objective-C의 메모리 관리 방법에 대한 설명.

Memory management: Favorite site

• 문씨의 강좌: 메모리 관리 Objective-C
• ObjC 객체의 retainCount 이야기
• [추천] OBJECTIVE-C의 메모리 관리 방법 ¹
• iOS 메모리 관리: retain/release/autorelease

Examples

문자열 포맷팅

NSString 클래스의 stringWithFormat 함수 사용.

int i = 1;
NSString *name = @"thefirstsong";
NSString *filename = [NSString stringWithFormat:@"%0d-%@.mp3", i, name];

NSString 와 CFStringRef 상호 변환

• Stackoverflow - NSString to CFStringRef and CFStringRef to NSString in ARC?

Typically:

NSString *yourFriendlyNSString = (__bridge NSString *)yourFriendlyCFString;

and

CFStringRef yourFriendlyCFString = (__bridge CFStringRef)yourFriendlyNSString;

Now, if you want to know why the __bridge keyword is there, you can refer to the Apple documentation. There you will find:

• __bridge transfers a pointer between Objective-C and Core Foundation with no transfer of ownership.
• __bridge_retained or CFBridgingRetain casts an Objective-C pointer to a Core Foundation pointer and also transfers ownership to you. You are responsible for calling CFRelease or a related function to relinquish ownership of the object.
• __bridge_transfer or CFBridgingRelease moves a non-Objective-C pointer to Objective-C and also transfers ownership to ARC. ARC is responsible for relinquishing ownership of the object.

NSString → CFString

:

// Don't transfer ownership. You won't have to call `CFRelease`
CFStringRef str = (__bridge CFStringRef)string;

// Transfer ownership (i.e. get ARC out of the way). The object is now yours and you must call `CFRelease` when you're done with it
CFStringRef str = (__bridge_retained CFStringRef)string // you will have to call `CFRelease`

CFString → NSString

:

// Don't transfer ownership. ARC stays out of the way, and you must call `CFRelease` on `str` if appropriate (depending on how the `CFString` was created)
NSString *string = (__bridge NSString *)str;

// Transfer ownership to ARC. ARC kicks in and it's now in charge of releasing the string object. You won't have to explicitly call `CFRelease` on `str`
NSString *string = (__bridge_transfer NSString *)str;

CFString to C string

• Stackoverflow - Converting a CFStringRef to char *

const char *cs = CFStringGetCStringPtr( cfString, kCFStringEncodingMacRoman ) ;
puts( cs ) ; // works

Sample

MotionSensorManager (Geosoft iOS MyCarNavi)

iPhone의 모션센서 데이터 취득 클래스.

See also

• Cocoa

Favorite site

• Wikipedia (en) Objective-C에 대한 설명
• Windows + GNUSTEP + CLANG 사용시 몇 가지 알아 둘 점
• Closure and anonymous functions in Objective-C ²
• Apple - The Objective-C Programming Language ³
• From C++ to Objective-C ⁴

References