Animate Controls down with change to UINavigationBar - ios

I have a UINavigationController with standard UINavigationBar. When presenting certain UIViewControllers and orientations, the UINavigationBar may or may not appear and it may or may not have a prompt element. This means that the bar height changes frequently.
I have some subviews below the UINavigationBar set with NSLayoutConstraints to topLayoutGuide. It generally lays out as expected, adjusting vertical position of the subviews appropriately based on the height of the UINavigationBar. What it does not do is move the subviews at times when the UINavigationBar is animated after the view is already displayed.
Specifically, coming from a state with UINavigationBar hidden, transition to a UIViewController which does not hide the navigation bar to one which does. The view displays, then navigation bar animates into place. The subviews do not move down. If I rotate the device, every things lays out appropriately again. Only when animating the navigation bar in and out or to display/hide the prompt I not find a hook to reevaluate the constraints.
I tried [self.view updateConstraints] and [self.view updateConstraintsIfNeeded] in various places such as viewDidAppear, viewDidLayoutSubviews. Nothing seems to update that topLayoutConstraint.
I am familiar with edge restraints, translucent navigation bar and other various methods of keeping the entire view from appearing under the navigation bar. I do want to keep view full size and I want the translucent bar so these are not solutions for me. It seems the constraints should handle this automatically, hence the "auto" in auto layout.
To simplify, for recreation, UINavigationController with rootViewcontroller showing normal navigation bar with just a title. In viewDidLoad of the next presented viewController I have [self.navigationContoller setPrompt:self.myPrompt]. The view is presented, when the prompt is set, the navigation bar grows larger. Some labels below the bar are set with relation to topLayoutGuide, which places them correctly initially. I expect they would move down when the bar grows. Rotate device back and forth, they now layout correctly. Pop the viewController and push back to top, repeats as above.

So, it turns out it was all me. After trying all manner of forcing layout updates in all sorts of ways, the solution was to move the [myView setPrompt:myPrompt] out of viewDidLoad and call it in viewDidAppear instead.
Works completely as expected. Navbar grows, subviews shift and shrink as needed. Now I have to hunt down all the experimental code I plastered everywhere trying to do it wrong.

Related

scroll up tableview to hide half of navigation bar and the whole table gets offset

I'm using a UITableViewController embedded in a navigation controller, I've checked the "hide bars on swipe" for the navigation controller in the storyboard. No crazy code, scrollview functions are not overridden, didn't write any code that would offset any views.
When I scroll up the tableview a tiny bit and release it when the navigation bar is half hidden, the whole table gets offset and it's off screen (sometimes the top left corner of the table is visible), then if I scroll up the table view a bit, it's back to its normal position, if I check "adjust scroll view insets" in the storyboard, the whole screen flashes black.
Has anyone encountered the same problem?
p.s. I'm using Xcode 9 beta with iOS 10.3, not sure if this has anything to do with it.
EDIT:
Scroll navigation bar half way
The view after releasing
So I created a new set of TableviewController and NavigationController, and tested it step by step by adding changes to it, it turned out that I had set my navigation bar to be translucent in the storyboard, once I unchecked it the issue was resolved. There's still an unwanted bounce effect if I release the navigation bar at half hidden position, which appears to be the view adjusting the offset, but it's way better than what it was like.
P.S. make sure "Adjust scroll view insets" is checked.
EDIT:
Turns out setting extendedLayoutIncludesOpaqueBars to True also resolves this issue, if you want to keep the navigation bar opaque.

UIPageController inside UINavigationController is offset from the top?

This a little bit wierd i have made UIPageController that works and everything is fine. But when i put it inside UINavigationController, it offset from the for status bar. Than i swipe up on that screen it positions itself right and everything is ok. I don't really understand what is happening. Here are the images
try setting adjustScrollViewInsets to false on UIPageController.
This is the property that determines whether the system should automatically add inset to a UIScrollView in your view controller's view hierarchy when it is being displayed behind transparent bars (here , the navigation bar). What happened here is that the system assumed the bounds of the page controller overlaps with that of the nav bar and so it adds insets so that the view's contents is fully visible and is not obscured by the nav bar. But in this case it is wrong since it seems your page controller's bounds starts at the bottom edge of the nav bar.
I think you can also set the nav bar as opaque to disable the automatic adding of insets.

Add UIView that hovers over UINavigationController's UINavigationBar, but pushes with the view that adds it?

So, adding a view that appears over the UINavigationBar in a UINavigationController is easy enough:
self.navigationController?.view.addSubview(testView);
However, getting that UIView to push/transition alongside UIViewController changes in that navigation flow is more tricky. Aside from simply fading the view alpha from 1 to 0 or vice versa on appear/disappear, is there an elegant solution/hack for getting the horizontal position of the view to stay centered, for example?
EDIT: The reason why setting titleView on the UIViewController's navigationItem won't work is because when another view is popping it clips the titleView... (compare this image to the one above)

Applying bar metrics on a standalone UINavigationBar

My app has a view controller that due to the fact it plays its own custom transition animations, provides its own standalone UINavigationBar view at the top (As opposed to using a UINavigationController).
When using an iPhone, and when rotating the device, I would like the UINavigationBar to automatically apply the landscape UIBarMetrics properties (eg, change height, change the background image, resize the buttons etc), but by default, it does not. This is a problem on iOS 7, since even if I manually change the height of the UINavigationBar, the UIBarButtonItem elements don't change their vertical positions.
Is there a way to manually 'tell' the UINavigationBar to apply specific bar metric properties to itself? Or is that actually an implementation inside UINavigationController, and not UINavigationBar?
After various testing and trial and error after asking this question, I eventually worked out a solution that fixed all of my issues, so I'll post it here under the solution I'd previously accepted.
When my app is displayed in landscape on an iPhone, I wanted the UINavigationBar at the top to shrink to the standardly accepted 32 points high, as is the case with any apps that use the UINavigationController class. However, as I am not using a UINavigationController for this particular view (for varying reasons of feasibility), I needed to implement this manually.
To account for the new transparent status bar in iOS 7, I adjusted the origin and size of the UINavigationBar so it encompassed both the bounds of the status bar, and the normal UINavigationBar region (ie, so the UINavigationBar frame origin was {0,0}, and the height was 52 points.)
Unfortunately, this happened:
While the bar itself is rendering at the proper position and height, all of the content in the bar, including the title and buttons are not positioned properly, being much too high, almost touching the status bar content.
It was pretty obvious what was happening. The navigation bar content is being vertically aligned to its own middle, completely disregarding the presence of the status bar content.
When I tested the same orientations with a normal UINavigationController, this was not the case, and the title and buttons in the UINavigationBar from the UINavigationController worked absolutely fine. Apple had done SOMETHING in there that wasn't part of the normal UINavigationBar implementation.
Going on this, I picked apart the view layout hierarchy of a UINavigationControllerto see what was happening to the UINavigationBar in there (Mainly calling a lot of NSLog() statements that would dump the subviews of the navigation bar.)
This is what I discovered:
From the looks of it, Apple have employed a relatively sneaky hack to achieve this effect. It turns out the actual UINavigationBar is actually placed right below the status bar (ie at point {0,20}) and only has a height of 32 points. Then, what happens is a private subview inside the UINavigationBar in charge of rendering the background is extended upwards, outside of the bounds of the navigation bar to encompass the region behind the status bar (ie, its origin is {0, -20}, and its height is 52 points, local to the navigation bar's subview coordinate space).
So by doing that, not only does the content vertically align properly, but the translucent effect still extends behind the status bar.
Anyway, after I discovered this, it was pretty straightforward to write a solution. All I needed to do was reposition and resize the UINavigationBar back to how I had it iOS 6 (ie, 20 points down, and only 32 points high), and then implement a UINavigationBar subclass that override the layoutSubviews method, grabbed the internal background view (Doing a quick subview check for a view with a class name that matched "Background"), and then manually extended it.
The bar metrics properties you can set on a UINavigation bar are things like background image and the title vertical position. Heigh and width need to be set from within your view controller.
If you need to manually tell the navigation bar to change it's size when the orientation changes you can implement the method - (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration1 in your view controller and change the size there.
Another option you can use is to use autolayout to specify that the width of your navigation bar is pinned to the left and right sides of its superview and let it figure out how wide it should be. For example
UINavigationBar *bar = [[UINavigationBar alloc] init];
bar.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:bar];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"H:|[bar]|"
options:0
metrics:nil
views:NSDictionaryOfVariableBindings(bar)]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"V:|[bar(44)]|"
options:0
metrics:nil
views:NSDictionaryOfVariableBindings(bar)]];

Using Autolayout, unable to move the navigation bar down 20px

I have a UITabBarController which has four tabs. One of those tabs opens a my results screen (a UITableViewController).
On showing this screen, I want to move the UINavigationBar down 20px (to make room for a custom UIStatusBar which I show on all screens).
On all my other screens, I add some code to the viewWillAppear method to change the self.navigationController.navigationBar.frame.origin.y to 20.
but these are all "non-root" screens (i.e. a pushed view with a back button).
However on THIS screen the UINavigationBar must be initially visible, even though it is the root view. I use the same code, but it doesn't move the view down.
I'm assuming autolayout is moving it back into position, so I tried adding this code into viewWillLayoutSubviews and viewDidLayoutSubviews. But when I do this the navigationbar doesn't move down until the first time the tableview is scrolled.
What do I need to do to force the navigationBar to move down (and stay down) before the screen appears?
Are you using storyboards? Set the Y in storyboards to 20, Make your viewcontroller implement UINavigation bar, then add this code:
-(UIBarPosition)positionForBar:(id<UIBarPositioning>)bar{
return UIBarPositionTopAttached;
}
This will tell the app that the navigation bar is to be attached, it will remain at 20px but extend the background all the way up.. So essentially it'll look like it's at y = 20.

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