Okay this may be just plain old user error. I followed the steps, minus the building of boost and openssl, since I already have them pre-built (although boost is not a framework).

I am more or less doing these steps:

git clone https://github.com/cristeab/ios-cmake.git
pushd ios-cmake
git apply ../fix_ios_cmake_compiler.patch
popd
mkdir build.debug
pushd build.debug
cmake .. -DCMAKE_BUILD_TYPE=Debug
make
popd

Which was listed in the instructions. This generates errors.

Determining if the include file pthread.h exists failed with the following output:
Change Dir: /Users/me/Development/3rdParty/cpprestsdk/Build_iOS/build.debug/build.i386/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/xcodebuild" "-project" "CMAKE_TRY_COMPILE.xcodeproj" "build" "-target" "cmTC_22e4e" "-configuration" "Debug"
=== BUILD TARGET cmTC_22e4e OF PROJECT CMAKE_TRY_COMPILE WITH CONFIGURATION Debug ===

Check dependencies
target specifies product type 'com.apple.product-type.tool', but there's no such product type for the 'iphonesimulator' platform

** BUILD FAILED **

The following build commands failed:
Check dependencies
(1 failure)

Both the ios-cmake and the contents of this Build_iOS directory seem a bit old. Is this even buildable for iOS anymore? While probably ill-advised, I was using http_client, which is really what I want this lib for. Mainly because I have the server already using cpprestsdk and thought it would be more convenient if I could use the client too. Maybe though that is the wrong approach here.