Flag to set CLANG_ENABLE_OBJC_WEAK to enable weak references in Xcode Project

SyntaX

Hey there :D

I was wondering if there is a specific flag configurable in my .pro file to enable weak references because every time I open the generated Xcode project, I get the following warning:

I already tried the following flags with no success:

QMAKE_LFLAGS += -ObjC

QMAKE_OBJECTIVE_CFLAGS += \
        -fobjc-arc \             # Synthesize retain and release calls for Objective-C pointers
        # TODO: find out where to put flag for weak references
        #-fobjc-runtime-has-weak \ # The target Objective-C runtime supports ARC weak operations --> unknown command
        #-fobjc-weak \           # CLANG_ENABLE_OBJC_WEAK --> seems to have no effect --> argument unused

My problem is, that I don't know the exact commands and where to put them, or if this is even supported?

thanks in advance
best regards
SyntaX