Click the button in any position, show a list of menu
// 1. Create view model, including title and image name.
letarrowMenuViewModel0=DPArrowMenuViewModel(title:"Find Teachers",
imageName:"iconProfessionalTeacherSemiBlack")letarrowMenuViewModel1=DPArrowMenuViewModel(title:"Find Language Partners",
imageName:"iconUserFriendsSemiBlack24")
viewModels.append(arrowMenuViewModel0)
viewModels.append(arrowMenuViewModel1)
// 2. Bind action, when user selects one of them
DPArrowMenu.show(view, viewModels: viewModels, done:{ index inprint(index)}){print("cancel")}