I’d like to create a small overlay view that would float on top of all the others. I need the view to accept touches and I need it to stay in place even during transitions between the underlying views. What I have tried so far:
Standalone view inserted into the key UIWindow. The obvious downside is that the view is not attached to any view controller, which means handling (at least?) rotation events by hand.
UIViewController containment, have a “root” view controller that would contain the floating view and all navigation would be done underneath it. This is very much a “first-class-citizen” solution, but presenting a modal view controller overlaps the floating view.
Second UIWindow with a root view controller containing the floating view. This goes against Apple recommendations and I had some trouble filtering which events should go to which window.
Does anyone have a working solution that doesn’t require too much brittle hacking?
In the end I have followed Jonathan’s suggestion and implemented the overlay as a separate view inserted into the key window. The view has an associated controller object (a subclass of NSObject, not UIViewController), and this controller takes care of the rotation logic. That way the view implementing the actual overlay object doesn’t need to care about rotation events at all.
Related
(I have read other questions and answers on this topic, but most are very old and do not relate to iOS 9 or 10.)
The app design calls for the top half of the display to always contain the same content. (An image being edited by the user.)
The bottom half of the display needs a UITableView. When a UITableViewCell is tapped, the bottom section needs to transition to a new UIViewController with slide-on animation, similar to how UINavigationController push segues work.
Problem: only the bottom view needs to transition to the new view controller(s), and back again. The upper half of the view hierarchy needs to remain unaffected. For this reason, I can't place everything inside a UINavigationController, and I can't have a UINavigationBar at the top of the screen.
Question: what approach should I take in such a situation, where I need only one UIView hierarchy to transition in push-segue fashion, but not anything else? Thanks.
Edited with Solution
Solution follows, for those following along at home.
Yes, you can actually use a UINavigationController for the bottom half.
If you are using Storyboards, the easiest way to do this is to use a container view for each part of the screen which you then can embed a UIViewController in for the top part and a UINavigationController in for the bottom part. If you are doing this programmatically, just add the view controllers as child view controllers to your app's initial view controller (see this answer for more info) which is essentially what the Storyboard will do for you automatically when using a container view.
As a child view controller, the UINavigationController will act independently from the top UIViewController and should behave as expected.
I recommend the programatic approach for the following reasons:
It helps you understand the inner workings of child/parent view controllers much better which will likely save you a significant amount of debugging time down the line.
It makes adding/removing/swapping child view controllers as simple as a few lines of code. Trying to do this with Storyboards is notoriously hacky and cumbersome.
It's much easier to keep track of changes using GIT (most mid-size/larger companies actually prohibit Storyboards for this very reason)
If you want change in part of the screen you can use container view. For details refer Swift - How to link two view controllers into one container view and switch between them using segmented control?
You can use multiple view in one view controller and can give animation like push or pop to show or hide it.
Second approach is you can use Container View which will give exact effect like navigation stack.
I have a vertical UIScrollView with several 'cards', nested UIViewControllers (via container views), each with their own state. Some of these cards can be expanded to take up the entire screen (what I'd effectively consider a full view controller transition) and later collapsed back to its original size. Ideally, we'd be segueing into these views, but apparently, transitioning into an already displayed view controller triggers an assertion. I'm currently experimenting with just changing the parent UIScrollView's contentOffset and any given card's bounds property upon expand/collapse, but this is proving to be a bit of a p.i.t.a. from several angles.
Is there any way to utilize a proper UIViewController transition for this?
Is there any way to utilize a proper UIViewController transition for this?
Consider instantiating a new instance of the same type of view controller, configuring it with the same data, and transitioning to that instead. That way you don't have to mess around with removing the controller from the container and putting it back later.
I am subclassing UIApplication to intercept and display touches in my TouchDisplay view. I would like to extend the Application, Window, Delegate or Main ViewController in order to keep my TouchDisplay view on top of all other views. As my and most other applications work, views and controllers are added and removed all the time. I figure the correct answer will be able to deal with these additions and removals and stil keep the TouchDisplay view on top.
Thanks for your help,
Joe
Here are a few approaches you could take for this:
If you're targeting iOS 5+ and iPad only, you can make a top-level view controller which has two contained view controllers. The first would be a view controller for your "TouchDisplay" view. The second would be the application's normal root view controller. (i.e. your existing main view controller; you'll need to set definesPresentationContext to YES on this view controller) Since you're writing the container view controller, you can order those two subviews however you like. There is a WWDC 2011 Talk on view controller containment that goes into great detail about this. This is the most "correct" approach IMHO, because it gives you a view controller for your TouchDisplay view, handles rotation and generally plays nice with others. (This only works on iPad, because on iPhone a new modal view always covers the full screen.)
A more straight-forward approach is to simply add your TouchView to your existing top-level UIWindow as a subview with addSubview:. Most applications don't actually remove the top-level view controller or add new top-level ones; they just present other view controllers from it. A view you add in the top-level window will stay above those. Of course, your app may not follow this rule, in which case you might try option #3 instead. This has rotation gotchas (your view will not auto-rotate when the device rotates, so you need to do this yourself.) You could also force your view back to top, say, on a 1-second timer, if you are having issues with other things covering it. This is also not as nice as option #1 because you don't get a UIViewController, just a UIView.
The most extreme approach is that you can create another UIWindow and give it a higher window level, such as UIWindowLevelAlert and put your TouchDisplay view in that. You can then make the window background transparent, and it will stay above your normal app content. There are lots of gotchas here, especially about auto-rotation and which window is the keyWindow (which is why you should use #1 or #2 instead if you can).
After some time I was able to get my app working. I have made an easy to use overlay that shows touch feedback over your existing application.
You can download the project here:
https://github.com/megaplow/FingerTracks/tree/master/FingerTracks
Happy coding,
Joe
I am subclassing UIApplication to intercept and display touches in my TouchDisplay view. I would like to extend the Application, Window, Delegate or Main ViewController in order to keep my TouchDisplay view on top of all other views. As my and most other applications work, views and controllers are added and removed all the time. I figure the correct answer will be able to deal with these additions and removals and stil keep the TouchDisplay view on top.
Thanks for your help,
Joe
Here are a few approaches you could take for this:
If you're targeting iOS 5+ and iPad only, you can make a top-level view controller which has two contained view controllers. The first would be a view controller for your "TouchDisplay" view. The second would be the application's normal root view controller. (i.e. your existing main view controller; you'll need to set definesPresentationContext to YES on this view controller) Since you're writing the container view controller, you can order those two subviews however you like. There is a WWDC 2011 Talk on view controller containment that goes into great detail about this. This is the most "correct" approach IMHO, because it gives you a view controller for your TouchDisplay view, handles rotation and generally plays nice with others. (This only works on iPad, because on iPhone a new modal view always covers the full screen.)
A more straight-forward approach is to simply add your TouchView to your existing top-level UIWindow as a subview with addSubview:. Most applications don't actually remove the top-level view controller or add new top-level ones; they just present other view controllers from it. A view you add in the top-level window will stay above those. Of course, your app may not follow this rule, in which case you might try option #3 instead. This has rotation gotchas (your view will not auto-rotate when the device rotates, so you need to do this yourself.) You could also force your view back to top, say, on a 1-second timer, if you are having issues with other things covering it. This is also not as nice as option #1 because you don't get a UIViewController, just a UIView.
The most extreme approach is that you can create another UIWindow and give it a higher window level, such as UIWindowLevelAlert and put your TouchDisplay view in that. You can then make the window background transparent, and it will stay above your normal app content. There are lots of gotchas here, especially about auto-rotation and which window is the keyWindow (which is why you should use #1 or #2 instead if you can).
After some time I was able to get my app working. I have made an easy to use overlay that shows touch feedback over your existing application.
You can download the project here:
https://github.com/megaplow/FingerTracks/tree/master/FingerTracks
Happy coding,
Joe
When using custom container view controller, I don't quite understand why the presenting view controller needs to specify the from, because being the container class, it should already know what's in the view hierarchy, no?
transitionFromViewController:toViewController:duration:options:animations:completion:
Container view controllers sometimes need to put the views of the contained controllers into specific subviews of their own view. (For example, a SplitViewController reimplementation might have left and right positioning views holding the master and detail controller views respectively.) Providing the fromViewController tells UIViewController where in the view hierarchy the new controller's view should be inserted, and also which specific view should be removed after the animation.
(contrary to another answer, the frames of the views aren't set for you at all. You do that, before the call, and in the animation block. The "Creating Custom Container View Controllers" system guide in the docs has a pretty good example.)
As it happens, actually using transitionFromViewController:... appears to be optional. You can manage your view hierarchy manually, with or without animations, and it works fine. I'm still forming my opinions, but I think I prefer to do it manually, to more easily handle cases where one of the VCs is nil.
This is done this way to allow you to have a view controller that has views with viewControllers in it. The from defines the originating view controller and gives the system the ability to position the animations appropriately.
Imaging you had a view with 4 views in it like tiles. the main view controller can consecutively call this on its "child" view controllers and with the from -> to specification, it won't make the assumption that the caller is the from viewController.