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Build static library *.so for Android. How?



  • Hello all!

    I am writing static library on Qt. There are Qt Project defined like:

    QT -= gui
    TEMPLATE = lib
    CONFIG += staticlib
    

    And everything OK for iOS. There are building library.a file for iOS. But not building library.so for Android, it's building the same file library.a too. Where to define it for building correct library.so file exactly for Android? I am working on Mac OS.



  • @bogong library.so is the shared object version. library.a is the static version, which is what you wanted. What's the problem?



  • @tom_h I don't know why but when I am building static in iOS everything works fine but on Android application crashed. I am trying to understand why it is and solve this issue. I've been always developing mono-block applications when everything is in one project. For now I am trying to separate UI and backend UI - Qt Quick Application, backend - static libraries *.a file. I thought that is because of static *.a (it's only my suggestions based on some libraries like openSSL and curl they build for iOS *.a files and for Android *.so).



  • Solution found. If you need something like described above look below for getting steps that work for me:

    • Define building static *.a for iOS/MacOS and shared *.so for Android in one backend project. Something like this:
    QT       -= gui
    TARGET = Library
    TEMPLATE = lib
    ios {
    	CONFIG += staticlib
    }
    macos {
    	CONFIG += staticlib
    }
    
    • In the UI Qt Quick Application define separately for each platform the library. Something like this:
    ios {
    
    	LIBS += -L$$PWD/../Libs/ios/ -lLibrary
    	PRE_TARGETDEPS += $$PWD/../Libs/ios/libLibrary.a
    }
    
    android {
    
    	QMAKE_LINK += -nostdlib++
    
    	equals(ANDROID_TARGET_ARCH,arm64-v8a) {
    		LIBS += -L$$PWD/../Libs/android_arm64-v8a/ -lLibrary
    		ANDROID_EXTRA_LIBS += $$PWD/../Libs/android_arm64-v8a/libLibrary.so
    	}
    	equals(ANDROID_TARGET_ARCH,armeabi-v7a) {
    		LIBS += -L$$PWD/../Libs/android_armeabi-v7a/ -lLibrary
    		ANDROID_EXTRA_LIBS += $$PWD/../Libs/android_armeabi-v7a/libLibrary.so
    	}
    	equals(ANDROID_TARGET_ARCH,x86) {
    		LIBS += -L$$PWD/../Libs/android_x86/ -lLibrary
    		ANDROID_EXTRA_LIBS += $$PWD/../Libs/android_x86/libLibrary.so
    	}
    }
    
    macos {
    	LIBS += -L$$PWD/../Libs/macos/ -lLibrary
    	PRE_TARGETDEPS += $$PWD/../Libs/macos/libLibrary.a
    }
    
    simulator {
    	LIBS += -L$$PWD/../Libs/macos/ -lLibrary
    	PRE_TARGETDEPS += $$PWD/../Libs/macos/libLibrary.a
    }
    
    

    I don't know why but static library *.a built from Qt project not working on Android. Only shared library project working for Android therefore need to separate it at time of building. I am building it on MacOS. Maybe on other OS different.


  • Lifetime Qt Champion

    AFAIK, that's because how the application has to be loaded on Android. It's a dynamic library that is loaded from the Java part.


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