How do I iterate over all CMake targets programmatically?

Turning my comment into an answer

To have a list of all targets is a wish that has been out there for a while, but the global property TARGETS is not yet implemented (as for May-2016, see "Listing all targets" discussion).

Edit: It is now implemented: Global BUILDSYSTEM_TARGETS property was released with CMake 3.7

So you can implement this yourself using CMake script itself - as @DevSolar as commented/answered or like here - but I've learned over the time working with CMake that you could also change a lot of target properties globally. E.g. most target properties are defaulted to an equivalent global variable setting.

You can take advantage of this in your case and solve this by adding the following to your global CMakeLists.txt file:

set(CMAKE_XCODE_ATTRIBUTE_GCC_GENERATE_DEBUGGING_SYMBOLS[variant=Debug] "YES")
set(CMAKE_XCODE_ATTRIBUTE_GCC_GENERATE_DEBUGGING_SYMBOLS[variant=MinSizeRel] "NO")
set(CMAKE_XCODE_ATTRIBUTE_GCC_GENERATE_DEBUGGING_SYMBOLS[variant=RelWithDebInfo] "YES")
set(CMAKE_XCODE_ATTRIBUTE_GCC_GENERATE_DEBUGGING_SYMBOLS[variant=Release] "NO")

set(CMAKE_XCODE_ATTRIBUTE_COPY_PHASE_STRIP[variant=Debug] "NO")
set(CMAKE_XCODE_ATTRIBUTE_COPY_PHASE_STRIP[variant=MinSizeRel] "YES")
set(CMAKE_XCODE_ATTRIBUTE_COPY_PHASE_STRIP[variant=RelWithDebInfo] "NO")
set(CMAKE_XCODE_ATTRIBUTE_COPY_PHASE_STRIP[variant=Release] "YES")

set(CMAKE_XCODE_ATTRIBUTE_GCC_OPTIMIZATION_LEVEL[variant=Debug] "0")
set(CMAKE_XCODE_ATTRIBUTE_GCC_OPTIMIZATION_LEVEL[variant=MinSizeRel] "s")
set(CMAKE_XCODE_ATTRIBUTE_GCC_OPTIMIZATION_LEVEL[variant=RelWithDebInfo] "3")
set(CMAKE_XCODE_ATTRIBUTE_GCC_OPTIMIZATION_LEVEL[variant=Release] "3")

set(CMAKE_XCODE_ATTRIBUTE_IPHONEOS_DEPLOYMENT_TARGET[variant=Debug] "7.0")
set(CMAKE_XCODE_ATTRIBUTE_IPHONEOS_DEPLOYMENT_TARGET[variant=MinSizeRel] "7.0")
set(CMAKE_XCODE_ATTRIBUTE_IPHONEOS_DEPLOYMENT_TARGET[variant=RelWithDebInfo] "7.0")
set(CMAKE_XCODE_ATTRIBUTE_IPHONEOS_DEPLOYMENT_TARGET[variant=Release] "7.0")

References

• XCODE_ATTRIBUTE_<an-attribute>
• CMAKE_XCODE_ATTRIBUTE_<an-attribute>

In correction to Florian's answer, BUILDSYSTEM_TARGETS is a not really a global property but a directory scoped one. A request for enhancement is currently open to request a truly global property. Using SUBDIRECTORIES property it's possible retrieve recursively all targets in the scope of the current directory with the following function:

function(get_all_targets var)
    set(targets)
    get_all_targets_recursive(targets ${CMAKE_CURRENT_SOURCE_DIR})
    set(${var} ${targets} PARENT_SCOPE)
endfunction()

macro(get_all_targets_recursive targets dir)
    get_property(subdirectories DIRECTORY ${dir} PROPERTY SUBDIRECTORIES)
    foreach(subdir ${subdirectories})
        get_all_targets_recursive(${targets} ${subdir})
    endforeach()

    get_property(current_targets DIRECTORY ${dir} PROPERTY BUILDSYSTEM_TARGETS)
    list(APPEND ${targets} ${current_targets})
endmacro()

get_all_targets(all_targets)
message("All targets: ${all_targets}")