                         it("sets the backgroundColor of fullscreenController to black") {
                             core.setFullscreen(true)
 
-                            expect(core.fullscreenController.view.backgroundColor).to(equal(.black))
+                            expect(core.fullscreenController?.view.backgroundColor).to(equal(.black))
                         }
 
                         it("sets the modalPresentationStyle of fullscreenController to .overFullscreen") {
                             core.setFullscreen(true)
 
-                            expect(core.fullscreenController.modalPresentationStyle)
+                            expect(core.fullscreenController?.modalPresentationStyle)
                                 .to(equal(UIModalPresentationStyle.overFullScreen))
                         }
 

                        it("sets core as subview of fullscreenController") {
                            core.setFullscreen(true)

                            expect(core.fullscreenController.view.subviews.contains(core)).to(beTrue())
                        }

                        it("set isFullscreen to true") {


                        expect(callbackWasCall).toEventually(beTrue())
                        expect(core.parentView?.subviews.contains(core)).to(beFalse())
                        expect(core.fullscreenController?.view.subviews.contains(core)).to(beTrue())
                        expect(core.isFullscreen).to(beTrue())
                    }

