Using QtCore based IOS Framework in IOS Project

fep29

I was able to successfully generate an IOS Framework named messenger_core using CMakeLists.txt The core of the code is written in C++ and uses qxmpp and QtCore, QtNetwork, and QtXml. I build everything in Xcode. And get no errors.

However when i try and import my messenger_core.framework into my IOS Front end app, set up all of the Header Searcg Paths and Framework Search Paths, System Search Paths, and library search paths. I stubbornly get the same error of:

QtIOS2/6.8.2/ios/lib/QtCore.framework/Headers/qttypetraits.h:10:10 'optional' file not found

in file included from
qxmpp/src/base/QXmppLogger.h:9:
in file included from
qxmpp/src/base/QXmppGlobal.h:13:
in file included from
QtIOS2/6.8.2/ios/lib/QtCore.framework/Headers/QString:1:
in file included from
QtIOS2/6.8.2/ios/lib/QtCore.framework/Headers/qstring.h:14:
in file included from
QtIOS2/6.8.2/ios/lib/QtCore.framework/Headers/qchar.h:8:
in file included from QtIOS2/6.8.2/ios/lib/QtCore.framework/Headers/qcompare.h:631:
in file included from QtIOS2/6.8.2/ios/lib/QtCore.framework/Headers/qcomparehelpers.h:18:

I have tried to set up my xcode build settings in my front end IOS to be identical to what is in my messenger_core.xcodeproj, messenger_core.pbproject, ive played with other linker flags. and everything else.

One high level question i immediately have, is it it even possible to treat QtCore.framework as installed by the qt isntaller as a normal IOS framework that can just be embedded into a prjoect and used, or is everything done through CmakeLists.txt?

fep29

As an addendum to this are there instructions out there to create a CMake configuration for a shared ios framework linking against static Qt6 libs to be embedded in an iOS app. Cause it really looks like just dragging and dropping QtIOS2/6.8.2/ios/lib/QtCore.framework into xcode doesnt work.

only Qt frameworks im using are:

QtCore.framework
QtNetwork.framework
QtNetwork.framework

As used by my qxmpp framework

fep29

CMakeLists.txt used to generate static library messenger_core.framework looks like this:

The consuming IOS Front end app results in error

QtIOS2/6.8.2/ios/lib/QtCore.framework/Headers/qttypetraits.h:10:10 'optional' file not found

when calling into messenger_core functions exposed by messenger_core *.h files.

cmake_minimum_required(VERSION 3.5)
project(messenger_core VERSION 1.0 LANGUAGES CXX)

# iOS Toolchain
set(CMAKE_SYSTEM_NAME "iOS")
set(CMAKE_XCODE_ATTRIBUTE_CODE_SIGNING_REQUIRED "NO") # Development; remove for release
set(CMAKE_TOOLCHAIN_FILE "/path/to/ios-cmake/ios.toolchain.cmake") # Correct path
set(CMAKE_IPHONEOS_DEPLOYMENT_TARGET "18.2") # Adjust as needed

# Options for QT
set (CMAKE_AUTOMOC ON)

# Qt Locations
set(CMAKE_PREFIX_PATH "/path/to/QtIOS/6.8.2/ios") # Correct path
find_package(Qt6 COMPONENTS Core Network Xml REQUIRED)

# QXmpp Locations
set(QXMPP_INCLUDE_DIR "/path/to/qxmppStatic/qxmpp/src")
set(QXMPP_LIBRARY_IOS "/path/to//qxmppStatic/qxmpp/build_ios/src/Debug-iphoneos/libQXmppQt6.a")

set(HEADERS
    include/ChatClient.h
    include/XmppSignaler.h
)

set(SOURCES 
    src/ChatClient.cpp
    src/MessengerCLI.cpp
    src/XmppSignaler.cpp
)

# Create a STATIC library (or SHARED if needed)
add_library(messenger_core SHARED
    ${HEADERS}
    ${SOURCES}
)

#link
target_link_libraries(messenger_core
    PUBLIC
    ${QXMPP_LIBRARY_IOS} # Explicitly link QXmpp - CRUCIAL
    Qt6::Core
    Qt6::Network
    Qt6::Xml
)

target_include_directories(messenger_core
    PUBLIC
    include
    ${QXMPP_INCLUDE_DIR}
    ${HEADERS}
)


target_compile_definitions(messenger_core PUBLIC QT_NO_KEYWORDS)

# iOS Specific Settings
set_target_properties(messenger_core PROPERTIES
    XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "c++17"
    PLATFORM "iphoneos"
    # Or for a static library: ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib"
    FRAMEWORK TRUE
    PUBLIC_HEADER "${HEADERS}"
    MACOSX_FRAMEWORK_IDENTIFIER "com.entity.messenger_core"
)

# Install the framework
# It takes the compiled messenger_core target (which Xcode has built) and creates 
# the .framework bundle.  The .framework bundle is then copied to the Frameworks 
# directory within the installation prefix.
install(TARGETS messenger_core 
    FRAMEWORK DESTINATION .
    PUBLIC_HEADER
)

fep29

A more complete set of steps:

Created a messenger_core.xcodeproj using a CMakeLists.txt: As seen above
Built the resulting project in xcode, and this generated a messenger_core.framework:

tree messenger_core.framework
messenger_core.framework
├── Headers
│ ├── ChatClient.h
│ └── XmppSignaler.h
├── Info.plist
└── doost_messenger_core

Create a clean new IOS App project from template.
Imported messenger_core.framework into IOS App
Update
Header Search path:
path/to/qxmppStatic/qxmpp/src

System Header Search Path:
/path/to/QtIOS/6.8.2/ios/lib/QtCore.framework/Headers
/path/to/QtIOS/6.8.2/ios/mkspecs/macx-ios-clang
/path/to/QtIOS2/6.8.2/ios/include

Library Search Path:
/path/to/qxmppStatic/qxmpp/build_ios/src/Debug-iphoneos #where libQXmppQt6.a resides

I have embedded the QtCore, QtNetwork, QtXml frameworks into the "Frameworks, Libraries, and Embedded Content" section of xcode, and ordered them correctly in build phases.

Getting error out of the basic IOS Executable front end when calling into messenger_core.framework functions:

QtIOS2/6.8.2/ios/lib/QtCore.framework/Headers/qttypetraits.h:10:10 'optional' file not found

jsulm

Try to set C++17 like this:

set(CMAKE_CXX_STANDARD 17)

std::optional requires C++17.

fep29

This post is deleted!

fep29

@jsulm thank you so much for the reply. The messenger_core framework builds fine. and yes it is set to C++17.

Its the consuming iOS front end executable that consumes the messenger_core.framework that is failing with above error. And i did indeed make sure to check that consuming iOS project uses C++17. I also tried GNU++20 with the same error.

I think one question that i have been struggle to get answered is can i even treat QtCore.framework, QtXml.framework, etc. (as installed here by the qt installer)

/path/to/Qt/6.8.2/ios/lib

like a normal IOS Framework and just embed it straight into Xcode?

Pardon the messiness of this post. I was still trying to wrap my mind around the situation as I was posting the question.

fep29

Solved. There is a difference in file extensions between objective-c and objective-c++ one is *.m other is *.mm I was calling C++ from a .m file. and that caused the error.