学步园

Afterwards just hit the “Build and Run” button and you're good to go or do the correct thing and just build (⌘B).

Once built, you can find the “libSDL.a” file in the “build/Debug-iphonesimulator” folder together with the headers. Unfortunately the headers are in a full canonical folder structure
(“usr/local/include” instead of “SDL”) which would be more helpful.

What you will have to do is to move and rename a bunch of files:

• libSDL.a -> libs/SDL/Debug/libSDL.a
• usr/local/include -> libs/SDL/include

For local development you only need a simulator build instead of the device one.

Creating the CMakeLists.txt

Once that is done, create a file called CMakeLists.txt next to your libs folder with the following contents:

cmake_minimum_required(VERSION 2.8)
project(MyApp)

set(HEADERS
    include/myapp/myapp.hpp
)
set(SOURCES
    src/main.cpp
)

set(IOS_FRAMEWORKS
    Foundation
    AudioToolbox
    CoreGraphics
    QuartzCore
    UIKit
    OpenGLES
)

set(CMAKE_OSX_SYSROOT iphonesimulator4.0)
set(CMAKE_OSX_ARCHITECTURES "$(ARCHS_STANDARD_32_BIT)")
foreach(FW ${IOS_FRAMEWORKS})
    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -framework ${FW}")
endforeach()

include_directories(
    ${CMAKE_CURRENT_SOURCE_DIR}/include
    ${CMAKE_CURRENT_SOURCE_DIR}/libs/SDL/include
)
link_directories(
    ${CMAKE_CURRENT_SOURCE_DIR}/libs/SDL
)

set(MACOSX_BUNDLE_GUI_IDENTIFIER "com.mycompany.\${PRODUCT_NAME:identifier}")

add_executable(
    MyApp
    MACOSX_BUNDLE
    ${HEADERS}
    ${SOURCES}
)

target_link_libraries(MyApp SDL)

If you want to run it on the phone you will need to change and add a bunch of things:

set(CMAKE_OSX_SYSROOT iphonedevice4.0)
set_target_properties(${NAME} PROPERTIES
    XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY "iPhone Developer: My Name")

In that case SDL will have to be built against the device and not the simulator. Once you're at that point, you should consider adding a switch to your configuration.

Hello iPhone

On the iPhone or other iOS devices you have OpenGL ES 2.0 to your disposal. Devices before the 3GS only have OpenGL ES 1.0, but these devices are slowly disappearing so for a small
project it's not worth the hassle to support both. The differences between those two are quite big (the former only does fixed function, the latter only does programmable pipeline). The following example however uses OpenGL ES 1.0 for simplicitly.

To verify that everything works, create these two files:

include/myapp/myapp.hpp:

#ifndef MYAPP_MYAPP_HPP_INC
#define MYAPP_MYAPP_HPP_INC

#include <SDL.h>
#include <SDL_opengles.h>

#endif

src/main.cpp

#include <iostream>
#include <cstdlib>
#include <myapp/myapp.hpp>

static const int screen_width = 320;
static const int screen_height = 480;

static SDL_Window *win;
static SDL_GLContext ctx;


void sdl_error_die()
{
    std::clog << "Error: " << SDL_GetError() << std::endl;
    exit(1);
}

int main(int argc, char **argv)
{
    if (SDL_Init(SDL_INIT_VIDEO) < 0)
        sdl_error_die();

    win = SDL_CreateWindow(NULL, 0, 0, screen_width, screen_height,
                           SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
    if (!win)
        sdl_error_die();

    ctx = SDL_GL_CreateContext(m_win);
    SDL_GL_SetSwapInterval(1);

    bool running = true;
    SDL_Event event;

    while (running) {
        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_QUIT)
                running = false;
        }

        glClearColor(1.0, 0.0, 0.0, 1.0);
        glClear(GL_COLOR_BUFFER_BIT);
    }

    SDL_GL_DeleteContext(ctx);
    SDL_DestroyWindow(win);
    SDL_Quit();
}

Switching to OpenGL ES 2.0

If you want an OpenGL ES 2.0 context and environment you need two things:

1. Change SDL_opengles.h to SDL_opengles2.h

2. Tell SDL you want an OpenGL ES 2.0 context

   SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
   

Make sure to call the latter before you create the window and context.

Building and Running

To build this now you need to run cmake with the XCode generator:

$ mkdir xcode
$ cd xcode
$ cmake -GXcode ..

This will generate an Xcode project inside the “xcode” folder. Open it and hit the “build and run” button. If everything works the simulator should start and show you a red window.

At that point you can operated with the device as if it was a regular SDL target. The accelerometer reacts as if it was a joystick and the touchscreen sends finger and button
touchevents. Currently the haptics support does not work on iOS so you won't be able to vibrate the device. However there are two ways out: you can either provide a patch for SDL which shouldn't be too hard, or add an objective C file yourself and send
the iPhone the appropriate commands yourself.

For more information about how SDL works on iOS read this followup
article about the behavior of SDL.