I want to pass data from one tabBar controller to another,
I am switching tabBar using tabBarController?.selectedIndex = 0
I tried many option but unable to pass data to another tab, is there any simple solution like we pass data using navigation controller?
Tabs are usually some custom UIViewControllers. From these view controllers (tabs) you can also get access to the UITabBarController with something like:
if let mainController = UIApplication.sharedApplication().delegate?.window??.rootViewController as? YourMainTabBarControllerClass {
mainController.someVariable = 123
}
Here you have to be careful, because the tab bar controller may not be the rootViewController, see this question for more details.
In order to store some properties in the UITabBarController you have to implement your own class by extending UITabBarController and then set the custom class in the StoryBoard. The class will then look like:
class YourMainTabBarControllerClass: UITabBarController {
// some custom variables here...
var someVariable = 0
...
}
Related
In my storyboard I got:
UIView -> UITabBarController -> UINavigationController -> UITableView
Now I want to pass an object from UIView into UITableview. I do get the object to the TabBarController from the prepare for segue func, but from there I kind of get lost.
How to identify what segue you have on the itemlist from the TabBarController?
Could somebody give some example code for the UITabBar and Navigation controller to pass the data?
Phillip is right.
You can do it as following:
class Model {
static let shared = Model()
var data: String // or anything else
}
in UIView:
Model.shared.data = "some data"
in UITableView
let data = Model.shared.data
//do smth with data...
Anton is suggesting the Singleton pattern. It is important to understand what it is when you decide to use it has both its benefits and potential pitfalls. https://thatthinginswift.com/singletons/ is a place to start reading up.
There are ways to just pass an object from one view to the other and that is useful knowledge to know. Both TabBarVC's and NavigationVC's have their viewControllers property which allows you to access an array of their child vc's. You can use this to pass information to specific child vc's. Depending on your needs this may be more appropriate than creating a singleton.
For example:
let childVC = tabBarVC.viewControllers[0] as! MyCustomVCClass
childVC.inheretedObject = objectIWantToSend
This would pass an object to the vc that ocupies the first tab of a tab bar vc.
I currently have three Swift files, one for the main view in a ViewController, and two more which are used for the two views within the first view, which are used for a Segmented Control.
As these don't use segues between each other, I can't use the prepareForSegue method to transfer data between them, so how do transfer the variables and such from one file to another?
This doesn't seem to be a duplicate as other cases such as the one commented are using segues, mine is not.
Are all three Swift classes view controller subclasses?
You have your main view controller with your segmented control. For each segmented, I would create a new view controller subclass.
On your main view controller, for each segment, use a 'Container View' instead of a UIView object.
This will create two new 'screens' in the storyboard, attached to your main view controller with a segue. These new screens will be UIViewControllers, you can change them to be your subclass's as normal.
You can now use your prepareForSegue function as normal to set data in your segmented control view controllers.
So you have something like viewControllerMain, which contains viewSegmentedOne and viewSegmentedTwo, and you want to be able to access `viewControllerMain.myProperty' ?
You can always navigate through the hierarchy to get parent views - but the easiest option could be to include a reference to viewControllerMain in each of the segmented controls
var myParentVC : ViewControllerMain?
then when you create the subviews
mySubView.myParentVC = self
If you are using storyboard for view controllers, then try like this:
let viewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Your_VC_Identifier");
viewController.Your_var = Your_value_to_assign
NOTE: Define Your_var in your ViewController class
You just need to create an instance of the view controller you want to display, this is easy such as calling on the storyboard instance (usually the presenting view controller has one) instantiateViewController(withIdentifier:), by using an identifier that you provide in the storyboard file.
One created you can pass the data you want by casting it to your view controller class and present it as you prefer.
One method would be using singleton class . https://cocoacasts.com/what-is-a-singleton-and-how-to-create-one-in-swift/ this is how you can make singleton class.
other method could be using nsuserdefaults.
You need to decide which approach is best according to your requirement.
try this:
let defaults = UserDefaults.standard()
defaults.set(yourdata, forKey: "someObject")
print(defaults.object(forKey: "someObject"))
You can try use Extensions for UIViewController
private var storedDataKey: UInt8 = 0
extension UIViewController {
var storedViewControllerData: UIViewController? {
get {
return objc_getAssociatedObject(self, &storedDataKey) as? UIViewController
}
set(newValue) {
objc_setAssociatedObject(self, &storedDataKey, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_ASSIGN)
}
}
}
This very useful you can send data with chain like:
viewControllerB.storedViewControllerData = viewControllerA.storedViewControllerData
or
func viewDidLoad() {
doSomething(self.storedViewControllerData)
}
I have a progress bar (with its own controller). This bar is supposed to be shown in different views depending on which view is visible. As the progress will be same, If possible I don't want to create many progress bar in many views rather I want to use same instance in all these views. Also in that way when I need to change any property of the progress bar it will be reflected commonly, which is required.
Please suggest me how can I use this common view. And also if my strategy is wrong, what would be the better design for such scenarios.
1) Well you have 2 options. You can declare a new Class ViewBox (or whatever name) and then use that inside your code
First View Controller
var box:ViewBox = ViewBox()
When you segue or transition to your next screen, you can have a predefined variable var box:ViewBox!. Then say when you press a button, the button has a function called transition.
//Now setup the transition inside the Storyboard and name the identifier "toThirdViewController"
override func prepareForSegue(segue:UIStoryboardSegue, sender:AnyObject?) {
if(segue.identifier == "toThirdViewController") {
var vc = segue.destinationViewController as! `nextViewController` //The class of your next viewcontroller goes here
vc.box = self.box
}
//Since The SecondViewController doesn't need ViewBox, we don't need it there.
}
where
nextViewController:UIViewController {
var box:ViewBox!
}
Or you could do a much simpler way and that is to look up a UIPageViewController :)
I am currently implementing the XLPagerTabStrip (https://github.com/xmartlabs/XLPagerTabStrip) which effectively creates a tab bar at the top of the view controller. I want to be able to segue to a new view controller from one of the tabbed controllers and be able to use the navigation bar to move backwards (or a custom version of the navigation bar if this isn't possible).
XLPagerTabStrip provides the moveToViewController and moveToViewControllerAtIndex functions to navigate between child view controllers, but this method doesn't allow use of a navigation bar to go backwards.
Conceptually XLPagerTabStrip is a collection of view controllers declared and initialized during the XLPagerTabStrip model creation.
It has virtually no sense to use a UINavigationController if you already have all the viewcontrollers available.
You can create a global var previousIndex to store the previous viewController index and allow users to go back by using canonical methods:
func moveToViewControllerAtIndex(index: Int)
func moveToViewControllerAtIndex(index: Int, animated: Bool)
func moveToViewController(viewController: UIViewController)
func moveToViewController(viewController: UIViewController, animated: Bool)
About a new viewController, suppose you have 4 viewControllers that built your container (XLPagerTabStrip) named for example z1, z2, z3 e z4.
You can embed to z4 a UINavigationController (so it have the z4 controller as rootViewController) and start to push or pop your external views. When you want to return to your z4 you can do popToRootViewControllerAnimated to your UINavigationController
When you are go back to z4 , here you can handle your global var previousIndex to moving inside XLPagerTabStrip.
I'm not familiar with XLPagerTabStrip, but I had a similar problem recently and the solution was to use an unwind segue to go back to the previous view controller. It's pretty trivial to implement so probably worth a try.
To navigate back to your previous view tab controller, you had initially navigated from;
Embed your new view controller, from which you wish to navigate
away from in a navigation bar
Connect it's Navigation Bar Button to the Parent view containing the
tab bar by dragging a segue between the 2 views
Create a global variable in App delegate to store current index
which you will use in the Parent view to determine what tab view
controller to be shown
var previousIndex: Int = 0 //0 being a random tab index I have chosen
In your new view controller's (the one you wish to segue from)
viewdidload function, create an instance of your global variable as
shown below and assign a value to represent a representative index
of the child tab bar view controller which houses it.
//Global variable instance to set tab index on segue
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.previousIndex = 2
You can write this for as many child-tab connected views as you wish, remembering to set the appropriate child-tab index you wish to segue back to
Now, create a class property to reference your global variable and a function in your Parent view as shown below
let appDelegatefetch = UIApplication.shared.delegate as! AppDelegate
The function
func moveToViewControllerAtIndex(){
if (appDelegatefetch.previousIndex == 1){
self.moveToViewControllerAtIndex((self.appDelegatefetch.previousIndex), animated: false)
} else if (appDelegatefetch.previousIndex == 2){
self.moveToViewControllerAtIndex((self.appDelegatefetch.previousIndex), animated: false)
}
}
You may now call this function in the Parent View Controller's viewDidLoad, as shown below.
moveToViewControllerAtIndex()
Run your project and that's it.
I have 1 tab bar controller in storyboard and 1 UIViewController associated with it. I would like to re-use the same UIViewController in order to create second item in tab bar. When I am creating second relation from tab bar to view controller I need to specify 2 different items names. How can I re-use same view controller and set different items names from storyboard? If not possible to do it in storyboard, then do I have to rename each in tab bar controller class or there is better way?
I was going to provide different data to view controller in prepareforsegue.
UPDATE:
little more details and clarification
In above screenshot marked VC at the moment is reachable a) directly from tab, b) through 3 transitions. I want to add another DIRECT relation to initial tab bar, just like in case of "a".
I can give you a little tweak for that and at least that worked for me.
Drag a tabbarcontroller and associated tab item view controllers to
your storyboard. Name them as you like.
Create an extra view controller that you want to reuse from your storyboard.
Add container views to each tab item view controllers and remove their default embedded view controllers.
Create embed segue from each tab item controller to your re-usuable view controller.
The configuration looks something like the following:
Thus you can use the same embedded VC for different tabbar item. Obviously if you need the reference of the tabbarcontroller, you need to use self.parentViewController.tabBarController instead of self.tabBarController directly. But it solves the issue of reusing a VC right from the storyboard.
I've found much simpler solution using storyboard only.
Setup your storyboard like this:
Then in your Navigation Controller Identity Inspector set Restoration ID like this:
And in your ViewController class file put the following code:
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.navigationItem.title = parent?.restorationIdentifier
label.text = parent?.restorationIdentifier
}
or do what you like based on parent?.restorationIdentifier value
If you don't want the Navigation TopBar to appear on the ViewController just set it to None in Attributes Inspector of the desired Navigation Controller like this:
That's it! Hope it helps.
Yes you can.
All you need to do is to create a new View Controller in StoryBoard as if there is going to be a different View Controller for tab 2. Then Select the 2nd view controller and simply add its class name the same classname of view controller 1
Things to note:
When you are sharing the same view controller class (.m ad .h) files, each tab will create a NEW instance of that class.
Edit:
This works as long as you have either a "custom" cell scenario (i.e. reusing two table view controllers) OR, have all your views inside a "container view" (i.e. reusing UIView).
I needed slightly different solution than the accepted answer. I needed to use same Table View Controller with the different data source for different tab bar items. So in the storyboard, i created two Navigation Controllers with same classes like this;
I also give different "Restoration ID" to each of them.
For the first one, I gave "navCont1" and "navCont2" for the second one.
In subclass("GeneralNavCont") of these Navigation Controllers; I override init method and check restoration id of self. Then i initiate my TableViewController and set its data source based on ids like this;
class GeneralNavCont: UINavigationController {
var dataSource1 = [Countries]()
var dataSource2 = [Cities]()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
initiateTableVCBasedOnId()
}
func initiateTableVCBasedOnId() {
let storyBoard = UIStoryboard(name: "Main", bundle: nil)
let tableVC = storyBoard.instantiateViewController(withIdentifier: "tableVC") as! MyTableViewController
if self.restorationIdentifier == "navCont1" {
tableVC.dataSource = self.dataSource1
self.viewControllers = [tableVC]
}
else if self.restorationIdentifier == "navCont2" {
tableVC.dataSource = self.dataSource2
self.viewControllers = [tableVC]
}
}
}
Hope it helps someone. Cheers.