将 Qt 导入现有的 Xcode 项目

Question

I am on MacOS 10.13.3, using Xcode 9 as my IDE, and trying to include Qt 5.10 in my Xcode project. I have installed Qt (with docs and examples) with Homebrew and ran many of them in QtCreator. Everything worked well up to this point.

My Xcode project is an extensive, complex project, the development of which has been active for a few years now, so switching to QtCreator or changing the structure of my project is not an option. I really need to add Qt to my existing Xcode project, which IMHO should be quite a natural thing to do given that Qt is a software development framework. However I have not been able to accomplish that yet. The upside is that in the process I have been learning quite a bit about Qt and its ecosystem. I now know how to use qmake, how to set up and successfully compile a project in QtCreator and how to create an Xcode project from QtCreator using qmake. As I said, I have been running many Qt examples and read pretty much every piece of documentation, blog and SO post I could find about this subject. To my surprise I haven't found a direct solution to this problem anywhere on the.net.

So far I have included in my Xcode environment QtCore.framework, QtWidgets.framework and QtGui.framework, configured Xcode with the right search paths (Qt finds its files and frameworks) and include the right Qt headers in the code. However upon building my target I get a series of meaningless compilation errors.

Basically - if my understanding is correct - I can't just import Qt's components and frameworks I need, and set the right paths in Xcode just like I would do with any other framework. Qt 'features' a preprocessing step using MOC and UIC that sets it apart from other tools. So I examined the output of qmake and there are two files that the building system produces - qt_makeqmake.mak and qt_preprocess.mak which I think are responsible for the code generation step. Basically this is what I don't know how to translate into my Xcode environment.

Please feel free to tell me if my approach is not correct. I am open to any advice or suggestion. I would really like to integrate Qt into my project as Qt is such a powerful and complete framework. I hope someone will be able to help. Thank you.

Answer 1

1 / In addition to setting the right path to Qt libraries and header files, which is fromwhat you said already done, you need to invoke the moc (Meta-Object Compiler) on your own Qt class which includes the Q_OBJECT macro. (basically every class you have made that are using signal/slot system).

MOC http://doc.qt.io/qt-5/moc.html

This step must be done BEFORE compiling the project, and the result (the cpp generated moc files) must be compiled AND linked.

Now I am not an expert in XCode and MacOS development but for sure you have a way to add a custom step in your build process for doing that

2/ For UIC files : follow approximatively what is explained here (answer of Preetam, not the one validated) to obtain a .cpp and an .h file that you must include in your project too.

Hope this answer will help and point you toward the rigth direction.

Here is a post explained more in detail what I explained : https://fmilicchio.bitbucket.io/2013/01/xcode-and-qt4-and-qt5/?

Answer 2

would you be kind to share how you have set the right path to Qt libraries and header files. In my current file in Xcode, I keep getting the "QtWidgets/QApplication' file not found".