ios - autoresize mask is making width of view to 0 -

in following code see if set autoresize mask of redview uiviewautoresizingflexiblewidth|uiviewautoresizingflexibleheight width of view made 0 after rotate screen.

but if make uiviewautoresizingflexiblewidth|uiviewautoresizingflexibleheight|uiviewautoresizingflexiblebottommargin|uiviewautoresizingflexiblerightmargin, behavior expected, view width , height scaled in proportion width , height of new screen.

why isn't setting flexibleheight , width not enough?

uiview *redview = [[uiview alloc] initwithframe:cgrectmake(50, 50, 100, 150)]; redview.backgroundcolor = [uicolor redcolor];  //this makes width 0 after rotation //redview.autoresizingmask = uiviewautoresizingflexiblewidth|uiviewautoresizingflexibleheight;  //this works redview.autoresizingmask = uiviewautoresizingflexiblewidth|uiviewautoresizingflexibleheight|uiviewautoresizingflexiblebottommargin|uiviewautoresizingflexiblerightmargin;  [self.view addsubview:redview];