UIViewControllerContextTransitioning and UINavigationControllerDelegate - ios

Question

My code :
navigator.m
- (void)newPushPage:(UIViewController *)controller
{
[self pushViewController:controller animated:YES];
}
- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
animationControllerForOperation:(UINavigationControllerOperation)operation
fromViewController:(UIViewController *)fromVC
toViewController:(UIViewController *)toVC
{
if (operation == UINavigationControllerOperationPush || operation == UINavigationControllerOperationPop)
{
self.animator = [Animator new];
return self.animator;
}
return nil;
}
animator.m
- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext
{
return 0.5;
}
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
UIViewController* toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIViewController* fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
[[transitionContext containerView] addSubview:toViewController.view];
toViewController.view.alpha = 0;
[UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
fromViewController.view.transform = CGAffineTransformMakeScale(0.1, 0.1);
toViewController.view.alpha = 1;
} completion:^(BOOL finished) {
fromViewController.view.transform = CGAffineTransformIdentity;
[transitionContext completeTransition:![transitionContext transitionWasCancelled]];
}];
}
After the pushPage and the screen appears, there is a problem : are visible all the elements that hide in the code and I can see how elements disappear already seeing the screen. It looks unsightly . There is a way ?

Answer 1

inside animateTransition (id)transitionContext protocol push and pop transition should has to be handled separately as below.
//1.Settings for the fromVC ..
UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
CGRect sourceRect = [transitionContext initialFrameForViewController:fromVC];
CGRect finalFrameForVC = [transitionContext finalFrameForViewController:toVC];
//2.Insert the toVC view.
if(pushCondition) {
UIView *container = [transitionContext containerView];
[container insertSubview:toVC.view aboveSubview:fromVC.view];
toVC.view.alpha = 0.5;
toVC.view =
} else if (popCondition ){
UIView *container = [transitionContext containerView];
toVC.view.frame = finalFrameForVC;
toVC.view.alpha = 0.5;
[container addSubview:toVC.view];
[container sendSubviewToBack:toVC.view];
UIView *snapShoot = [fromVC.view snapshotViewAfterScreenUpdates:false];
}
//3.Perform the animation.
[UIView animateWithDuration:1.0
delay:0.0
usingSpringWithDamping:1.0
initialSpringVelocity:6.0
options:UIViewAnimationOptionCurveLinear
animations:^{
//Setup the final parameters of views for push
toVC.view // update final view frame
toVC.view.alpha = 1.0;
//Setup the final parameters of views for pop
snapShoot.frame =
} completion:^(BOOL finished) {
//When the animation is completed call completeTransition with final push value
[snapShoot removeFromSuperview];
//When the animation is completed call completeTransition with final push value
toVC.view.alpha= 1.0;
[transitionContext completeTransition:YES];
}];
Create enum / flag property inside amimator and set it inside navigation controller delegate.
if (operation == UINavigationControllerOperationPush)
{
self.animator = [Animator new];
self.animator.pushPopAnimation = UINavigationControllerOperationPush;
return self.animator;
}
See the apple documentation of snapshotViewAfterScreenUpdates:(BOOL)afterUpdates method in code above.