i have the following situation:
In my TabBarController i have multiple tabs and it all works fine, but:
The destination of one specific tab is dynamic.
If a certain condition matches, this specific tab should open a NavigationViewController.
If an other condition matches, this specific tab should open a ViewController.
Are there any built in solutions?
How can i modify the destination of a tab at runtime?
Greetings and thanks
Long long ago, in a galaxy far far away...
Segues didn't even exist. So yeah
The UITabBarController has a setter in which you can pass the new view controllers you want it to handle. You won't be able to decide what shows at the point of the tapping this way, but you'll be able to change the controllers as the condition changes.
open func setViewControllers(_ viewControllers: [UIViewController]?, animated: Bool)
If you however DO need to decide as the tab is tapped... You could have your tab controller direct to a controller that's essentially empty, and use view controller containment for that controller to have the 2 options on it, and have one of them hidden. Pretty doable from the storyboard with very little supporting code. I think I prefer this option.
If you would rather continue to use Segues, then you can perform a specific Segue depending on the state of some condition variable like this:
func presentAppropriateView() {
if condition {
performSegue(withIdentifier: "ToNavBar", sender: self)
} else {
performSegue(withIdentifier: "ToVC", sender: self)
}
}
write a delegate method which you want to perform on certain condition on runtime and call
[self.tabBarController setSelectedIndex:0];
where index could be of your choice
Related
I want my app to check at start conditionaly if a variable is correct or not. Based on that it should either go to an intro screen (where he can select a variable in my case select a team) or it should start the main view. After searching i found this code and edited it. But there still seems to be problems. First of all I dont have two identifier. The Intro has one but not the main view. My main View is called WeatherViewController and the Intro screen is called FirstScreenViewController. I also added a picture of my Main.storyboard.
I also googled a lot about conditional UINavigationController but I can only understand with a video and did not found a video about it.
I tried to use the code from here.
var id = hello ? "goToIntro" : "???"
self.window = UIWindow(frame: UIScreen.main.bounds)
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let WeatherViewController: UIViewController = mainStoryboard.FirstScreenViewController(withIdentifier: WVC has no identifier??) as UIViewController
self.window?.rootViewController = WeatherViewController
self.window?.makeKeyAndVisible()
if hello {
self.performSegue(withIdentifier: "goToIntro", sender: self)
} else {
/here nothing should happen. It should open the Main View
self.performSegue(withIdentifier: "???", sender: self)
}
Note: This answer was referring to the original question (before any edits) that was attempting a segue inside loadView().
You're supposed to manually create your controller's view in loadView. You're currently doing nothing, hence the black screen. Furthermore, if you are using a Storyboard or a xib for managing this controller you shouldn't be overriding loadView at all.
Having said that it might be a better idea to move this branching logic a step back, to "something" (a container controller like a UINavigationController or a custom one, or even directly setting the root controller of your window if it makes sense) that will present (or set) A or B based on some condition and thus avoid to load this controller altogether (have in mind that in your code, the controller is initialized, it will be part of the hierarchy and all the lifecycle methods will be called even if you segued directly to another one)
Finally, if you decide for some reason to override loadView you don't have to call viewDidLoad yourself, the system will call this method.
I am writing a macOS application with multiple view controllers, using Storyboards.
In my main View Controller I would like to be able to copy and paste data to the NSPasteboard. The data is related to buttons displayed to the user, and the exact data to be copied varies depending on which button has most recently been pressed/selected.
I would like to be able to override the standard behaviour of the Copy and Paste NSMenuItems when my main View Controller is the front most (key) window, but revert to back to standard behaviour when other windows are in the foreground, as they all contain NSTextFields which can be copied/pasted into.
I have done a lot of googling, and overriding this behaviour is not very well documented. I can achieve it globally by adding an IBAction into the App Delegate, which I could use to call a function in whichever View Controller is key, but this doesn't feel like a very elegant solution.
Currently my IBAction in the App Delegate looks like this:
#IBAction func copy(_ sender: Any) {
if let window = NSApplication.shared.keyWindow {
if let splitView = window.contentViewController as? SplitViewController {
if let controlVC = splitView.controlItem.viewController as? ControlViewController {
controlVC.copyAction(self)
}
}
}
}
Am I missing a neater solution?
Thanks,
Dan
I have a segue from one view controller to another, which was created in the storyboard of my project. I'm wondering if there is a way to change or get rid of that segue through code. Thanks, using Xcode 9 Swift 4.
Apparently it's not possible... look at the answer on this post. And the documentation says this about creating segues:
"You do not create segue objects directly. Instead, the storyboard runtime creates them when it must perform a segue between two view controllers."
Although it's not about changing or deleting the segue, I think it's the same logic.
If you just want to avoid the segue to happen you can do that inside "shouldPerformSegue" (like vacawama said in the comments):
override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool {
if identifier == "aSegueIWantToDisable" {
return false
}
return true
}
I'm using a library that manages the swiping between view controllers.
It seems like the only way that I can use a button in one of my view controller to navigate to the other is by calling a specific method from the view controller that manages the swiping feature.
It there any way to call a method in a different view controller?
Thank you
There are many ways to communicate between view controllers. One of the most common patterns for doing so on iOS is the delegate pattern. One view controller holds a reference to the other and the delegate conforms to a protocol. The protocol is a set of methods that the first view controller can call when specific events happen. I would try setting up a protocol and have one of your view controllers be a delegate to the other
If you take a look at the code that is hosted on GitHub you can see that the page controller is exposed from the EZSwipeController class. So given that you subclass EZSwipeController (or maintain a reference somewhere), you can now access the pageViewController property of it and scroll to a given page.
If you subclass:
class MyVC : EZSwipeController{
func buttonTapped(){ /* use self.pageViewController to "page" */ }
}
Weirdly, I have never personally worked with UIPageViewController, and as far as I can tell there is no easy way to scroll to a page in an easy fashion.
I haven't personally tried it (I usually validate my answers before posting), but you should be able to pull it off. If you don't have a reference to the view controller you need to get it (let me know if that is the core issue).
There is a question on SO that seems to enjoy some popularity regarding UIPageViewController paging:
UIPageViewController, how do I correctly jump to a specific page without messing up the order specified by the data source?
And from Apple docs:
I would also encourage you to look at the code inside of the EZSwipeController repo, where you can find a non-exposed method that does the scrolling:
#objc private func clickedLeftButton() {
let currentIndex = stackPageVC.indexOf(currentStackVC)!
datasource?.clickedLeftButtonFromPageIndex?(currentIndex)
let shouldDisableSwipe = datasource?.disableSwipingForLeftButtonAtPageIndex?(currentIndex) ?? false
if shouldDisableSwipe {
return
}
if currentStackVC == stackPageVC.first {
return
}
currentStackVC = stackPageVC[currentIndex - 1]
pageViewController.setViewControllers([currentStackVC], direction: UIPageViewControllerNavigationDirection.Reverse, animated: true, completion: nil)
}
The "key" line is this one:
pageViewController.setViewControllers([currentStackVC], direction: UIPageViewControllerNavigationDirection.Reverse, animated: true, completion: nil)
I think EZSwipeController also exposes the view controllers contained in the pageViewController which is a property called stackVC, which is an array of the view controllers contained in the page view controller.
I assume with this knowledge you should be able to page to a given page, despite seeming a little "hacky" (IMHO the developers should have exposed paging logic from the get-go).
My advice for you after all this is simple:
Try to roll it yourself. This is not a huge undertaking and you maintain full control over what's accessible and how you want to work with it. The EZSwipeController class is quite small, so there is not a whole lot of code you'd have to write for your own solution. You could also go ahead and fork the repo and modify/use it to your liking.
I hope that helps. If you have any further questions or if something is unclear, I'd be ready to help you out.
Currently on my viewController : Upload, my button send the data to my database only if all the information are filled out, and I come back to the preview view (table View) with :
self.navigationController?.popViewControllerAnimated(true)
I would like, if it is possible, to come back to my main view on the tabBarController. I tried many things, like directly on the storyboard with Present modally segue to "TabBar controller", but I come back to the TabBar without sending my data to the database and without checking in the information are filled out..
How can I do it?
Thanks!
UITabBarController has a property selectedIndex with which you can switch the selected tab. So on completion after dismissing the UploadViewController you can run:
self.tabBarController?.selectedIndex = 0 // Index to select
It would probably be best to create a delegate for your UploadViewController to fire a function to do all the work in your previewVC on API call completion.
(Super late response...in case someone has similar questions, presumably in later version of Swift, such as mine which is Swift 5, iOS 13.2). Steps:
Be sure to set an id for your UITabBarController storyboard, e.g. "TabBarViewController"
Next, add the following to an action that has already been connected to a button:
let ID_TABBAR = "TabBarViewCOntroller"
#IBAction func returnToTabbar(_ sender: Any) {
let tabBarController = self.storyboard?.instantiateViewController(identifier:ID_TABBAR) as! UITabBarController
self.navigationController?.pushViewController(tabBarController, animated:true)
}
Referenced from one of the responses from this post.
Update: In case your Tab Bar View Controller also happens to be the root view controller, the two lines of the code in the returnToTabbar method above can be:
self.dismiss(animated:true, completion:nil);
self.navigationController?.popViewController(animated:true);
(ref.: See answer here, for Swift4 but works just fine in Swift5)