Связь интерфейса QML с C++

const QMetaObject::Connection connection = QObject::connect(
                &engine, &QQmlApplicationEngine::objectCreated,
                &app, [&](QObject *object, const QUrl &url) {
            if (url != mainQml)
            return;

            if (!object)
            app.exit(-1);
            else
            QObject::disconnect(connection);
}, Qt::QueuedConnection);

#include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

#ifndef APPCORE_H
#define APPCORE_H

#include <QObject>

class AppCore : public QObject
{
    Q_OBJECT
    using BaseClass = QObject;
public:
    explicit AppCore(QObject *parent = nullptr);
    // Метод, который принимает некоторый указатель на QObject
    Q_INVOKABLE void receiveFromQml(QObject* someObject);

signals:

public slots:
};

#endif // APPCORE_H

#include "AppCore.h"

#include <QDebug>

AppCore::AppCore(QObject *parent) :
    BaseClass(parent)
{

}

void AppCore::receiveFromQml(QObject *someObject)
{
    someObject->setProperty("text", "Hello world");
}

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include "AppCore.h"

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    AppCore appCore;
    QQmlContext* context = engine.rootContext();
    context->setContextProperty("appCore", &appCore);

    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

import QtQuick 2.9
import QtQuick.Window 2.2
import QtQuick.Controls 2.2

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")

    Text {
        id: text
        text: qsTr("Empty Text")
        anchors.centerIn: parent
    }

    Button {
        text: qsTr("Press Me")
        anchors.top: text.bottom
        anchors.topMargin: 20
        anchors.horizontalCenter: parent.horizontalCenter

        onClicked: {
            // Просто передаём id текстового поля. В данном случае будет передан указатель на QObject
            appCore.receiveFromQml(text)
        }
    }
}

cmake_minimum_required(VERSION 3.1)

# Имя проекта ProjName
project(ProjName LANGUAGES CXX)

# Искать подключаемые файлы в директории сборки
set(CMAKE_INCLUDE_CURRENT_DIR ON)

set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTORCC ON)

# C++11
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# Компилятор Clang для C
SET (CMAKE_C_COMPILER             clang)
# Флаги
SET (CMAKE_C_FLAGS                "-Wall -std=c99")
SET (CMAKE_C_FLAGS_DEBUG          "-g")
SET (CMAKE_C_FLAGS_MINSIZEREL     "-Os -DNDEBUG")
SET (CMAKE_C_FLAGS_RELEASE        "-O3 -DNDEBUG")
SET (CMAKE_C_FLAGS_RELWITHDEBINFO "-O2 -g")

# Компилятор Clang для C++
SET (CMAKE_CXX_COMPILER clang++)
# Флаги
set(CMAKE_CXX_FLAGS                "-Wall -std=c++11")
set(CMAKE_CXX_FLAGS_DEBUG          "-O0 -g")
set(CMAKE_CXX_FLAGS_MINSIZEREL     "-Os -DNDEBUG")
set(CMAKE_CXX_FLAGS_RELEASE        "-O3 -DNDEBUG")
set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g")

# Авто поиск *.cpp, *.h, *.ui, *.qrc в директории проекта (без поддиректорий)
FILE(GLOB SOURCE_FILES ${PROJECT_SOURCE_DIR}/*.cpp)
FILE(GLOB HEADER_FILES ${PROJECT_SOURCE_DIR}/*.h)
FILE(GLOB UI_SRC_FILES ${PROJECT_SOURCE_DIR}/*.ui)
FILE(GLOB UI_QRCS ${PROJECT_SOURCE_DIR}/*.qrc)

# Иконка приложения для Windows
FILE(GLOB ICON_RCS ${PROJECT_SOURCE_DIR}/*.rc)

# Модули Qt (Widgets, QtGui, QtCore, QtPrintSupport)
find_package(Qt5 COMPONENTS Widgets PrintSupport REQUIRED)

# Ресурсы *.qrc
qt5_add_resources(UI_RESOURCES_RCC ${UI_QRCS})

# Папка для релиз версии исп. файла
if(CMAKE_BUILD_TYPE STREQUAL "Release")
    if(WIN32)
        set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/Winows)
    elseif(UNIX)
        set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/Linux)
    endif()
endif()

# Исп. файл
if(WIN32)
    add_executable(${PROJECT_NAME} WIN32 ${SOURCE_FILES} ${HEADER_FILES}
        ${UI_SRC_FILES} ${UI_RESOURCES_RCC} ${ICON_RCS})

    # Qt модули
    target_link_libraries(${PROJECT_NAME} Qt5::Widgets Qt5::PrintSupport)    
else()
    add_executable(${PROJECT_NAME} ${SOURCE_FILES} ${HEADER_FILES}
        ${UI_SRC_FILES} ${UI_RESOURCES_RCC})

    target_link_libraries(${PROJECT_NAME} Qt5::Widgets Qt5::PrintSupport)
endif()

IDI_ICON1 ICON DISCARDABLE "ProjICO.ico"