objective c - Flip view controllers inside bigger view controller will flip the main view controller -

i want flip view controller has smaller size screen. using transitionfromviewcontroller flip whole screen. , want smaller view controller flipped.

first login should visible, after flipped register view should available!

my code is

- (void)showlogin {     vclogin = [[loginviewcontroller alloc] initwithnibname:@"loginviewcontroller" bundle:nil];     [self.view addsubview:vclogin.view];     [self addchildviewcontroller:vclogin];      if (is_ipad()) {         vclogin.view.center = self.view.center;     } }  - (void)showregister {     vcregister = [[registerviewcontroller alloc] initwithnibname:@"registerviewcontroller" bundle:nil];     [self.view addsubview:vcregister.view];     [self addchildviewcontroller:vcregister];      if (is_ipad()) {         vcregister.view.center = self.view.center;     }      [vclogin willmovetoparentviewcontroller:nil];      [self transitionfromviewcontroller:vclogin toviewcontroller:vcregister duration:0.5f options:uiviewanimationoptiontransitionflipfromleft animations:^{} completion:^(bool finished) {         [vclogin removefromparentviewcontroller];         [vcregister didmovetoparentviewcontroller:self];     }]; } 

i tried [uiview transitionfromview:...] result same! suggestions? thanks!

have tried core animation? might use code below , have 1 view controller subviews.

    [uiview transitionfromview:viewone                         toview:viewtwo                       duration:1.0f                        options:uiviewanimationoptiontransitionflipfromright | uiviewanimationoptionshowhidetransitionviews                     completion:(^(bool finished){     })];