CMake with iOS Toolchain: Can't Find Threads

None of these solutions seem to work. I found the only thing that consistently worked for me was to set the variables that FindThreads.cmake sets. In other words, define the following in your toolchain file:

set(CMAKE_THREAD_LIBS_INIT "-lpthread")
set(CMAKE_HAVE_THREADS_LIBRARY 1)
set(CMAKE_USE_WIN32_THREADS_INIT 0)
set(CMAKE_USE_PTHREADS_INIT 1)

The problem is indeed due to the call to try_compile failing in FindThreads.cmake. But for me setting CMAKE_CXX_COMPILER_WORKS was not enough. Instead, I changed the type of test performed by try_compile from trying to build an executable to trying to build a static library, by putting this in the toolchain file:

set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)