source: trunk/doc/src/development/developing-on-mac.qdoc@ 569

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/*!
    \page developing-on-mac.html
    \title Developing Qt Applications on Mac OS X
    \brief A overview of items to be aware of when developing Qt applications
        on Mac OS X
    \ingroup platform-specific

    \tableofcontents

    Mac OS X is a UNIX platform and behaves similar to other Unix-like
    platforms. The main difference is X11 is not used as the primary windowing
    system. Instead, Mac OS X uses its own native windowing system that is
    accessible through the Carbon and Cocoa APIs.  Application development on
    Mac OS X is done using Xcode Tools, an optional install included on every
    Mac with updates available from \l {http://developer.apple.com}{Apple's
    developer website}. Xcode Tools includes Apple-modified versions of the GCC
    compiler.


    \section1 What Versions of Mac OS X are Supported?

    As of Qt 4.6, Qt supports Mac OS X versions 10.4 and up. It is usually in
    the best interest of the developer and user to be running the latest
    updates to any version. We test internally against Mac OS X 10.4.11 as well
    as the updated release of Mac OS X 10.5 and Mac OS X 10.6.

    \section2 Carbon or Cocoa?
    
    Historically, Qt has used the Carbon toolkit, which supports 32-bit
    applications on Mac OS X 10.4 and up. Qt 4.5 and up has support for the Cocoa
    toolkit, which requires 10.5 and provides 64-bit support.

    This detail is typically not important to Qt application developers.  Qt is
    cross-platform across Carbon and Cocoa, and Qt applications behave
    the same way when configured for either one. Eventually, the Carbon
    version will be discontinued. This is something to keep in mind when you
    consider writing code directly against native APIs.

    The current binary for Qt is built in two flavors, 32-bit Carbon and full
    universal Cocoa (32-bit and 64-bit). If you want a different setup for
    Qt will use, you must build from scratch. Carbon or Cocoa is chosen when
    configuring the package for building. The configure process selects Carbon
    by default, to specify Cocoa use the \c{-cocoa} flag.  configure for a
    64-bit architecture using one of the \c{-arch} flags (see \l{universal
    binaries}{Universal Binaries}).

    Currently, Apple's default GCC compiler is used by default (GCC 4.0.1 on
    10.4 and 10.5, GCC 4.2 on 10.6). You can specify alternate compilers
    though. For example, on Mac OS X 10.5, Apple's GCC 4.2 is also available
    and selectable with the configure flag: \c{-platform macx-g++42}.  LLVM-GCC
    support is available by passing in the \c{-platform macx-llvm} flag. GCC
    3.x will \e not work. Though they may work, We do not support custom-built
    GCC's.

    The following table summarizes the different versions of Mac OS X and what
    capabilities are used by Qt.

    \table
        \header
            \o Mac OS X Version
            \o Cat Name
            \o Native API Used by Qt
            \o Bits available to address memory
            \o CPU Architecture Supported
            \o Development Platform
        \row
            \o 10.4
            \o Tiger
            \o Carbon
            \o 32
            \o PPC/Intel
            \o Yes
        \row
            \o 10.5
            \o Leopard
            \o Carbon
            \o 32
            \o PPC/Intel
            \o Yes
        \row
            \o 10.5
            \o Leopard
            \o Cocoa
            \o 32/64
            \o PPC/Intel
            \o Yes
        \row
            \o 10.6
            \o Snow Leopard
            \o Cocoa/Carbon
            \o 32
            \o PPC/Intel
            \o Yes
        \row
            \o 10.6
            \o Snow Leopard
            \o Cocoa
            \o 64
            \o Intel
            \o Yes
    \endtable
    
    Note that building for ppc-64 is not supported on 10.6.

    \section2 Which One Should I Use?

    Carbon and Cocoa both have their advantages and disadvantages. Probably the
    easiest way to determine is to look at the version of Mac OS X you are
    targetting.  If you are starting a new application and can target 10.5 and
    up, then please consider Cocoa only. If you have an existing application or
    need to target earlier versions of the operating system and do not need
    access to 64-bit or newer Apple technologies, then Carbon is a good fit. If
    your needs fall in between, you can go with a 64-bit Cocoa and 32-bit
    Carbon universal application with the appropriate checks in your code to
    choose the right path based on where you are running the application.

    For Mac OS X 10.6, Apple has started recommending developers to build their
    applications 64-bit. The main reason is that there is a small speed
    increase due to the extra registers on Intel CPU's, all their machine
    offerings have been 64-bit since 2007, and there is a cost for reading all
    the 32-bit libraries into memory if everything else is 64-bit.  If you want
    to follow this advice, there is only one choice, 64-bit Cocoa.

    \target universal binaries
    \section1 Universal Binaries

    In 2006, Apple begin transitioning from PowerPC (PPC) to Intel (x86)
    systems.  Both architectures are supported by Qt. The release of Mac OS X
    10.5 in October 2007 added the possibility of writing and deploying 64-bit
    GUI applications. Qt 4.5 and up supports both the 32-bit (PPC and x86) and
    64-bit (PPC64 and x86-64) versions of PowerPC and Intel-based systems.

    Universal binaries are used to bundle binaries for more than one
    architecture into a single package, simplifying deployment and
    distribution. When running an application the operating system will select
    the most appropriate architecture. Universal binaries support the following
    architectures; they can be added to the build at configure time using the
    \c{-arch} arguments:

    \table
        \header
            \o Architecture             
            \o Flag
        \row
            \o Intel, 32-bit
            \o \c{-arch x86}
        \row
            \o Intel, 64-bit
            \o \c{-arch x86_64}
        \row
            \o PPC, 32-bit
            \o \c{-arch ppc}
        \row
            \o PPC, 64-bit
            \o \c{-arch ppc64}
    \endtable

    If there are no \c{-arch} flags specified, configure builds for the 32-bit
    architecture, if you are currently on one. Universal binaries were initially
    used to simplify the PPC to Intel migration. You can use \c{-universal} to
    build for both the 32-bit Intel and PPC architectures.

    \note The \c{-arch} flags at configure time only affect how Qt is built.
    Applications are by default built for the 32-bit architecture you are
    currently on. To build a universal binary, add the architectures to the
    CONFIG variable in the .pro file:

    \code
    CONFIG += x86 ppc x86_64 ppc64
    \endcode


    \section1 Day-to-Day Application Development on OS X

    On the command-line, applications can be built using \c qmake and \c make.
    Optionally, \c qmake can generate project files for Xcode with
    \c{-spec macx-xcode}. If you are using the binary package, \c qmake
    generates Xcode projects by default; use \c{-spec macx-gcc} to generate
    makefiles.

    The result of the build process is an application bundle, which is a
    directory structure that contains the actual application executable. The
    application can be launched by double-clicking it in Finder, or by
    referring directly to its executable from the command line, i. e.
    \c{myApp.app/Contents/MacOS/myApp}.

    If you wish to have a command-line tool that does not use the GUI (e.g.,
    \c moc, \c uic or \c ls), you can tell \c qmake not to execute the bundle
    creating steps by removing it from the \c{CONFIG} in your \c{.pro} file:

    \code
    CONFIG -= app_bundle
    \endcode


    \section1 Deployment - "Compile once, deploy everywhere"

    In general, Qt supports building on one Mac OS X version and deploying on
    all others, both forward and backwards. You can build on 10.4 Tiger and run
    the same binary on 10.5 and up.

    Some restrictions apply:

    \list
        \o  Some functions and optimization paths that exist in later versions
            of Mac OS X will not be available if you build on an earlier
            version of Mac OS X.
        \o  The CPU architecture should match.
        \o  Cocoa support is only available for Mac OS X 10.5 and up.
    \endlist

    Universal binaries can be used to provide a smorgasbord of configurations
    catering to all possible architectures.

    Mac applications are typically deployed as self-contained application
    bundles. The application bundle contains the application executable as well
    as dependencies such as the Qt libraries, plugins, translations and other
    resources you may need. Third party libraries like Qt are normally not
    installed system-wide; each application provides its own copy.

    The most common way to distribute applications is to provide a compressed
    disk image (.dmg file) that the user can mount in Finder. The Mac
    deployment tool (macdeployqt) can be used to create the self-contained bundles, and
    optionally also create a .dmg archive. See the
    \l{Deploying an Application on Mac OS X}{Mac deployment guide} for more
    information about deployment. It is also possible to use an installer
    wizard. More information on this option can be found in
    \l{http://developer.apple.com/mac/}{Apple's documentation}.
*/