I have a complex navigation problem that I was hoping someone may be able to give me some insight as to the best way to approach this problem. I've been Googling and have found multiple different suggestions for similar problems, but none of them seem to quite nail down my problem.
I have a UITabBarController. Each tab is set up with it's own Navigation stack, as it should have.
One of those tabs uses a UISegmentedControl with three segments. Each of those segments needs to have its own view controller and navigation stack, independent of one another and of the navigation stack that the tab bar controller controls for its tab. Basically, it needs to work like a UITabBarController within a tab of a UITabBarController, but display the tabs as a UISegmentedControl.
Also, when at the root controller of each tab, the navigation stack should be the stack that it came in from, so that it pops out to the table view that it came in from.
I hit a snag and feel like I would have to have some brutal hack to go forward, no matter what I try. Any and all help will be greatly appreciated.
I would strongly prefer to be able to handle the connections in Storyboard, so as to keep my storyboard nice and pretty, but if it must be done in code, I can do that too.
Edit
I have something of a solution. In the base class:
private func show(segment: SelectedSegment) {
var equipmentStoryboard: UIStoryboard!
switch segment {
case .SelEquipment:
equipmentStoryboard = UIStoryboard(name: "EquipmentDetailEquipmentSegment", bundle: nil)
case .SelHistory:
equipmentStoryboard = UIStoryboard(name: "EquipmentDetailHistorySegment", bundle: nil)
case .SelPlans:
equipmentStoryboard = UIStoryboard(name: "EquipmentDetailPlansSegment", bundle: nil)
}
if let newSegmentController = equipmentStoryboard.instantiateViewController(withIdentifier: segment.getSegmentIdentifier()) as? EquipmentDetailSegmentsViewController {
var controllerStack = self.navigationController?.viewControllers
controllerStack?.removeLast()
controllerStack?.append(newSegmentController)
self.navigationController?.setViewControllers(controllerStack!, animated: false)
}
}
#IBAction func didTapSegmentedControl(_ sender: UISegmentedControl, forEvent event: UIEvent) {
let newSelectedSegment = SelectedSegment(rawValue: sender.selectedSegmentIndex)
self.show(segment: newSelectedSegment!)
}
I'm not happy about it though. I'd like to:
Not have to re-instantiate each controller every time the segment is tapped.
Be able to storyboard it (may not be possible without an actual UISegmentedControlController or something like that)
I actually found the right solution to the problem. I had to write a custom system. I'm going to come back to this and work on it at some point so that I can provide a github project with the API that would provide this functionality to anyone publicly.
Basically, the system does this:
Scrollable Segmented Control that is expandable to as many segments as desired.
A "SegmentNavigationController", which is a UIViewController because it contains views that are swapped to, brought to front, shown, (and rest hidden) when tapping on the respective segment.
Each segment has it's own navigation stack, which is simply an array of the view controllers that control the views in the current segment.
Custom animation takes place when pushing and popping an item to/from the navigation stack, to make it appear to be a natural iOS controller. The segmented control stays in place, while the new view animates in.
Navigation is retained, so that when switching between segments, you can resume where left off when tapping a different segment.
Utilizes the Clean Swift Architecture: http://clean-swift.com
I'm posting this as an answer because a custom system was the best solution after days of deliberation on the subject.
This is of course also a preliminary to possibly expanding this system to something useful and reusable.
Related
Apologies as I know there are some similar questions, but I've been looking for two weeks through every one I can find, and cannot figure it out (I'm a bit of a novice).
I have a few different View Controllers, not using a Navigation Controller. I can segue between them no problem. The issue is, I need each view to be dismissed when I segue to a new one. Here is some of what I've tried so far.
Option 1 (in new View Controller)
override func viewDidAppear(_ animated: Bool) {
presentingViewController?.dismiss(animated: false, completion: nil)
}
Option 2 (in old View Controller)
override func viewDidDisappear(_ animated: Bool) {
self.dismiss(animated: false, completion: nil)
}
In both of these cases, the new view gets dismissed and I'm taken back to the old view. I've tried about 20 versions of similar code.
Should I be using the first VC in my program as my "main" view controller, and presenting/dismissing all others on top of it? I didn't think this approach seemed memory efficient, when the "main" VC is not often used after initially loading the app.
It seems like I'm missing or not understanding something. Any help would be greatly appreciated.
Think of it this way: A view controller can't exist on an island. It has to be presented on top of something.
That means when you present one VC on top of another, the presenting view controller is the "foundation" for the new one you just presented.
If you don't want to present VCs on top of each other, you have a couple of options:
1) Use a navigation controller. This is probably the best approach. You can present or push any view controller. If you decide to push, you can remove the old one from the navigation stack, or you can keep it there so the user can go back. There are lots of ways to use a navigation controller, and it's easily the most flexible way to navigate between controllers.
2) Use a tab bar controller. This works best if you have just a few different view controllers in your app, but it's good for certain use cases.
3) Do exactly what you said in your post (use the root view controller to present/dismiss all other VCs). As I said, you can't present a view controller out of thin air-- there always has to be something behind it. Unless there's a ton of stuff going on in your root VC, this shouldn't cause any memory issues. This approach should be fine unless you're very particular about the animations between your view controllers.
In general, I wouldn't worry too much about memory usage until it becomes a problem. It should be fine to present view controllers on top of each other for 99% of normal use cases.
if you want to present VC B from VC A and want to dismiss VC A while Presenting you can use this Code
let parentVC = presentingViewController
dismiss(animated: true) {
let vc = self.storyboard!.instantiateViewController(withIdentifier...)
parentVC.present(vc, animated: true)`enter code here`
} `enter code here`
So I am working on an app and am finally getting to a point where I am starting to build actual modules instead of playgrounds and utility apps for tests. So I really want to do this right since I am jumping into the real deal right now. I was hoping to get advice that will help me accomplish my goals for the apps "flow" without me hacking something together that will come back to bite me later.
So imagine I have a home screen(a single view controller) that can branch to multiple storyboards. The mechanism I want to trigger transitions is the user grabbing an image on the home screen with their finger, and flicking it off the screen. When the image is no longer on screen, I'd like to transition to a storyboard that corresponds to that image. For instance, the user might flick the "settings" image to open a settings panel.
[home storyboard] -- [user flicks image off screen] --> [alternate storyboard]
I have already accomplished this kind of, but with the way I am doing it now I am unsure how to be able to navigate back from the second storyboard back to the home storyboard. It also seems unclean and hacky to me.
Right now it is set up as such:
Home is its own storyboard - main.storyboard
Home contains one simple viewcontroller
Alt is another storyboard - alt.storyboard
Alt contains a navigationcontroller
How can I facilitate things such that Alt's navigation controller will recognize that it was just in the Home storyboard, so that it will provide a "back" button for navigating back home?
Or, if anyone has any advice as to how I might accomplish this in a neater way, I would greatly appreciate it. I want each "module" (ie alt.storyboard's contents) to be in different storyboards for organizational sake.
Here is the code I use to seque to my second storyboard:
if !(recognizer.view!.window == nil) {
print("object left window")
let viewController: UIViewController = (self.storyboard?.instantiateViewControllerWithIdentifier("Alt"))! as UIViewController
self.presentViewController(viewController, animated: true, completion: nil)
}
Thanks so much for taking the time to check this out, let me know if I have not been clear enough.
you could put the main viewcontroller (from Home storyboard) itself into a navigation controller and simply push the initial viewcontroller from the storyboard you want to reach (in your example Alt storyboard) with a custom transition. so the viewcontrollers from all the other storyboards except of Home should not be embedded in a navigation controller!
I am running into a problem here. I am presenting views with performSegueWithIdentifier. Everything goes smoothly. The problem is that as a test, I only have 2 viewControllers with some data in them and I have two buttons that call a segue back to the other VC. If I keep performingSegues, you can clearly see that the memory usage goes up every two segues by around 0.4Mb. This tells me that the Views are not being deleted/removed from the view stack and are just using memory. I would like to know the correct way of getting rid of the view that presents the other view by using performSegueWithIdentifier (of course, after it finished presenting the view, else it will not work I guess).
Could you point me in the right direction? I found some objective-c code that tried to do this but it was very extensive and I don't know much about objective-C, so it was a little hard for me to understand.
Thank you in advance for your help!
Cheers!
Edit:
I am doing a "manual segue". By this I mean I have two view controllers standing on their own. They are not embedded in any navigationVCs or something like that. I am using an "Adaptive Segue" of type "Show".
If your goal is to always keep one VC, and since you already have a manual segue, what you can do is, after presenting the next VC you can pop the existing VC from the root and assign the destination VC as your root VC like so
class ManualSegue: UIStoryboardSegue {
override func perform() {
sourceViewController.presentViewController(destinationViewController, animated: true) {
self.sourceViewController.navigationController?.popToRootViewControllerAnimated(false)
UIApplication.sharedApplication().delegate?.window??.rootViewController = self.destinationViewController
}
}
}
When you do normal segues, you are piling up new view controllers on top of the existing ones without dismissing them. That's why your memory usage keeps going up.
You need to provide more information before we can give you specific guidance. Are you doing modal segues or pushing onto a navigation stack?
If you're pushing, you want to pop to the view controller you came from. Think in terms of a stack of plates. When you push, you add plates to the stack. When you pop, you take plates off and reveal the plates (view controllers) underneath. Do a search in the Xcode help system on "PopTo" to find the methods that let you either pop back to a specific view controller or back to the root view controller of your navigation controller.
Modal view controllers stack on top of each other in a similar fashion, but without the origination of a navigation controller. If you've pushed a series of one or more modals and you send the dismissViewControllerAnimated:completion: method to the view controller you want get back to it will dismiss the modals that are on top of it.
You can also look at using unwind segues. Unwind segues let you go back where you came. Do a search in the Xcode help system on "Using unwind segues" for more information. Most of the tutorials on unwind segues are written in Objective-C but you should be able to find some in Swift if you look. Explaining unwind segues in enough detail to be useful is more than I can cover in this answer.
I have been looking for a solution to this for quite some time but I still fail to see what the best solution is:
I am trying to swap view controllers programmatically, without anything in the storyboard, pure swift files.
As far as I see presentViewController() just creates a 'modal' which would cause the previous ViewController to stay in the memory (tested this, deinit never fires for the first controller). The solution I have found is to switch the rootViewController: self.view.window?.rootViewController = ViewController2() -> this fires deinit of the first one.
While this solution would work in theory, I am wondering...
Is there some recommended way or best practice of how to do this programmatically? Or is it really just about changing the viewRootController's value?
How do you structure your app? Do you use one ViewController and you swap views? Or you present other ViewControllers as modals with presentViewController? (I am totally new to this and I can't seem to find any good source; most of the articles deal with storyboard)
Thanks a lot!
EDIT: I will add: my test app is not supposed to have any kind of navigation for different viewcontrollers (no tabs, nor anything like that). It basically works like screen1->screen2->screen3->screen4. If a reset button is pressed, it gets back to screen1. I am purely interested of swapping ViewControllers, nothing else.
1: Changing the main window's root view controller is correct for swapping view controllers.
2: Generally, swapping view controller is not used. You can use a navigation controller that has a root view controller (eg. your main screen) and then push other view controllers as needed. Tab bar view controllers are also very useful.
https://developer.apple.com/library/ios/documentation/WindowsViews/Conceptual/ViewControllerCatalog/Chapters/CombiningViewControllers.html#//apple_ref/doc/uid/TP40011313-CH6-SW1
Hope this helps!
1.
The basic ways are:
navigationController?.popViewControllerAnimated(true)
or just pop to root view
navigationController?.popToRootViewControllerAnimated(true)
pushing can be done similarly
or setting a new stack
navigationController?.setViewControllers([viewController], animated: true)
These are the recommended ways of navigating in code just pick the one appropriate to your specific situation.
The push and pop mechanism is probably the most recommended way of doing general navigation.
Try to always use navigation controllers and only use modal views when appropriate.
Use navigation controllers when navigating through your main views. Modal views can be used as side views or extension to the view presenting that view modally.
Edit:
There are many ways of efficiency navigating through an app. In this particular case pushing and popping the navigation stack is probably the best way to go. But keep in mind that there are Tab bar controllers, collection views and others. At the end of the day The best is to look at your app structure and based on that decide which navigation method is the best for you.
Right I have looked at a few SO questions on the subject and I am finding it difficult to come up with the correct solution here.
Requirements
I have a UITabBar based application. One of the tabs has a UINavigation controller with UISegmentedControl at the top allowing the user to switch between three different views.
Each view will have a UITableView which will allow the user to navigate to another view. These views should be pushed onto to the navigation controller.
Problem
Now all the SO questions and Answers on the subject show how to switch between views. However I need the view I switch to, to allow pushing of another view onto the navigation stack. I am not sure this is even possible. I thought about UIViewController containment - however that would show a view being pushed onto the stack in a smaller window that the screen's bounds. Not what I am looking for.
Any ideas how I can solve this with storyboards and UIViewControllers?
UPDATE
Here is what I am trying to do: In the screenshot the container area is where I need to load other view controllers into. The UISegment control cannot go into the navigation bar as that space is used for something else. So that's why I think UIViewController containment might be better here?
So even though this isn't using separate TableViewControllers, you can use different custom UIViews that are hidden by default and become visible when you select it's corresponding button. This will unfortunately make it so you have all three view's logic in the same VC.
To get around this, you can try setting up some delegates and mimicking the TableViewController logic separation by sending out the didSelectTableAtIndexPath, UIGesture touches, etc into classes outside the ViewController to help keep your code cleaner.
User UITabBarController and hide the tab bar.
- (void)viewDidLoad
{
self.tabBar.hidden = YES;
}
Binding the segment control with method valueChanged
- (void)valueChanged:(UISegmentedControl *)seg
{
if ([seg.selectedSegmentIndex == 0]) {
self.selectedIndex = 0;
} else if ([seg.selectedSegmentIndex == 1] {
self.selectedIndex = 1;
}
}
I achieve this by this way, I hope this will help.