I have a tabBar application with 4 different ViewControllers.
Is it possible to call the same method from all the 4 views, where do I have to put the method?
For the record it is just a call to show a iAd banner.
Thanks
This would work. Create a custom subclass of UITabBarController. Put your function in there. Be sure the change the class of the TabBarController in the Storyboard to CustomTabBarController.
class CustomTabBarController: UITabBarController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
func myFunctionToCallFromAnywhere() {
print("Hey, it works")
}
}
Then in your viewControllers that are managed by your TabBarController you can call the function like this:
(self.tabBarController as? CustomTabBarController)?.myFunctionToCallFromAnywhere()
Related
Learning some view controller basics and am stuck on how to dismiss a modal with a button.
In my slimmed-down example, I have a two view setup with the initial view and the modal. The first view has a button that successfully pops up the modal. On the modal, there is a button that should dismiss itself.
According to other posts and documentation, I should be able to run simple code attached to the button like this:
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func CloseModal(_ sender: Any) {
self.dismiss(animated: true, completion: nil)
}
}
When I tap the "Close Modal" button nothing happens. What am I missing here? Am I putting this code in the wrong place? Currently, it's in the main ViewController.swift file.
The other approach is to use an unwind segue to your main view controller. Just add an “unwind action” in the first view controller:
class ViewController: UIViewController {
#IBAction func unwindHome(_ segue: UIStoryboardSegue) {
// this is intentionally blank
}
}
Just give this unwind action a meaningful name, unwindHome in this example, so that, if and when you have multiple unwind actions later on, you can easily differentiate between them.
Then you can control-drag from the button in the second scene to the “exit” control and select the appropriate unwind action:
This has a few nice aspects:
The “close” button no longer cares how you presented it, it will unwind however is appropriate (e.g. if you later change the initial segue to be a show/push segue, the unwind segue will still work without any code changes).
Because you’re now using a segue to unwind, the presented view controller can use its prepare(for:sender:) to send data back, should you eventually need to do that.
If you want, you can unwind multiple scenes. For example if A presents B, and B presents C, you can obviously unwind from C to B, but you can also unwind all the way from C to A if you want.
So, while dismiss works, unwind segues are another alternative.
You actually have two ViewController screens, but it looks like you have one ViewController class? And is the 2nd screen connected to a class?
Must be in the class that belongs to the second screen of the closeModal method.
//This is First ViewController, OpenModal Button is here
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
}
// The name of the class and the Viewcontroller in the storyboard have to be the same, and CloseModol Button and function need to be here
class SecondViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func CloseModal(_ sender: Any) {
self.dismiss(animated: true, completion: nil)
}
}
Don't forget to set the name of the ViewController in Storyboad;
from FirstViewController to SecondViewController
Ive been searching and i cant seem to find out how to disable all tab bar items EXCEPT the home button from being used until a user logs in or creates and account
You can do something like below, create a custom class(TabBarController), extend it from UITabBarController, and write code inside TabBarController class.
Assign TabBarController class to your UITabBarController
extension TabBarController: UITabBarControllerDelegate{
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
// allow your desired controller to be tapped
if tabBarController.selectedIndex == indexOfHomeControllerInTabBar {
return true
}
return false
}
}
Note: Apple doesn't recommend blocking tabbars, for more info check this link https://developer.apple.com/design/human-interface-guidelines/ios/bars/tab-bars/
here is my approach
note that it is kinda a hack way so you might modify as per your needs
you will conform to UITabBarControllerDelegate and make your VC the delegate for it in the viewDidLoad
then in the "didSelect viewController" delegate method callback you will do your logic and override the selected index as below code
class ViewController: UIViewController, UITabBarControllerDelegate {
// MARK: Lifecycle Methods
override func viewDidLoad() {
super.viewDidLoad()
self.tabBarController?.delegate = self
}
func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
if /* your logged in logic */ {
self.tabBarController?.selectedIndex = 0 /* assuming that the home is at index 0 */
}
}
}
note if you did this step in base VC it will be much better and code saving for you
You can loop for all items in your Tabbar and disable items you want
for i in 0..<tabbarController.tabBar.items!.count {
let item = tabbarController.tabBar.items![i]
item.isEnabled = i == indexOfHomeTab
}
Put this somewhere in viewDidLoad()
if let viewControllers = self.tabBarController?.viewControllers {
for viewController in viewControllers {
if viewController != viewControllers[0] { // assuming your homeViewController index is 0
tabBarController?.tabBarItem.isEnabled = false
}
}
}
The short answer is probably "Don't do that." Tabs in a tab bar are supposed to let the user switch between always-available screen at the top level of your UI. If you read Apple's HIG I suspect you will find that what you are trying to do is not recommended.
Better to have each of the other screens show some sort of disabled/inactive state.
In my HomeViewController have four section:
Banner
Popular Product
New Product
Old Product
All are .xib files and they are working fine.
Now I want to add ActivityIndicator in my HomeViewController
So now I want to show ActivityIndicator on HomeViewController until all the .xib's file not fully loaded in HomeViewController as .xib's ActivityIndicator should hide.
Now, the problem for me is that how can I get the confirmation about .xib's loaded to HomeViewController or not?
As a pretty simple direct solution, you could follow the delegation approach. So, when "Popular Product" View complete the needed process, you should fire a delegate method which will be handled by the view controller.
Example:
consider that in PopularProduct class you are implementing a method called doSomething() which need to get called and finish its work to hide the activity indicator from the view controller and it should send Data instance to the view controller. You could do it like this:
protocol PopularProductDelegate: class {
func popularProduct(popularProduct: PopularProduct, doSomethingDidPerformWith data: Data)
}
class PopularProduct: UIView {
// ...
weak var delegate: PopularProductDelegate?
func doSomething() {
// consider that there is much work to be done here
// which generates a data instance:
let data = Data(base64Encoded: "...")!
// therefore:
delegate?.popularProduct(popularProduct: self, doSomethingDidPerformWith: data)
}
// ...
}
Therefore, in ViewController:
class ViewController: UIViewController {
// ...
var popularProduct: PopularProduct!
override func viewDidLoad() {
super.viewDidLoad()
// show indicator
popularProduct.doSomething()
}
// ...
}
extension ViewController: PopularProductDelegate {
func popularProduct(popularProduct: PopularProduct, doSomethingDidPerformWith data: Data) {
print(data)
// hide indicator
}
}
Furthermore, you could check my answer for better understanding for delegates.
Im new to swift and iOS development.I have a doubt regarding protocol and delegate methods.
I have a 4 vc's say vc1,vc2,vc3,vc4.And i'm navigating from vc1->vc2->vc3-vc4->vc1. That is from vc4, im poping using navigation controller back to vc1.
i have a protocol and methods in it like
protocol myProtocol{
func myFunc()
}
In vc4, im making a delegate as,
var delegate:myProtocol?
and im using it in a button action as
if let delegate = self.delegate{
delegate.myFunc()
}
and also pop vc4 back to vc1.
Now in VC1,im extending myProtocol as
class vc1:myProtocol{
override func viewDidLoad()
{
let vcProtocol = vc4()
vc4.delegate = self
}
func myFunc()
{
print("executing this")
}
}
But its not working. Can i do like this?
How can i connect these to classes with delegate and protocol.Please help me
viewDidLoad is only executed once if the controller is not destroyed.
Try calling in viewWillAppear for example.
Also, you do not need to change the delegate of vc4, just set the delegate to vc1 again (in viewWillAppear).
Have you tried Notification?
In your VC1 ViewController ViewDidLoad method:
NotificationCenter.default.addObserver(self, selector: #selector(myFunc, name: NSNotification.Name(rawValue: "aNotificationName"), object: nil)
In your VC4 when the myFunc is needed:
NotificationCenter.default.post(name: Notification.Name("aNotificationName"), object: nil)
You can get the viewController from the navigation stack which has the same type as your first viewController and then assign it as the delegate object in your vc4.
For instance:
In vc4's viewDidLoad, you may do this
for viewController in self.navigationController?.viewControllers{
if viewController.isKindOfClass(YourVC1ControllerType){
self.delegate = viewController
}
}
I assume that your vc1,vc2,vc3, etc have their own ViewController custom classes.
Another way of implementing this would be to get the first controller from the self.navigationController?.viewControllers array and setting it as the delegate object in vc4.
//In viewDidLoad of vc4
delegate = self.navigationController?.viewControllers.first as! HomeController
or,
//In viewDidLoad of vc4
delegate = self.navigationController?.viewControllers.[indexOfTheController] as! HomeController
I have an optional bool variable called showSettings on my first view controller which is called ViewController, and I'm popping from SecondViewController back to ViewController.
Before I pop, I want to set the bool to true. Seems wrong to instantiate another view controller since ViewController is in memory.
What's the best way to do this? I'm not using storyboards, if that's important for your answer.
Thanks for your help
So I figured it out, based mostly from this post – http://makeapppie.com/2014/09/15/swift-swift-programmatic-navigation-view-controllers-in-swift/
In SecondViewController, above the class declaration, add this code:
protocol SecondVCDelegate {
func didFinishSecondVC(controller: SecondViewController)
}
Then inside of SecondViewContoller add a class variable:
var delegate: MeditationVCDelegate! = nil
Then inside of your function that your button targets, add this:
self.navigationController?.popViewControllerAnimated(true)
delegate.didFinishSecondVC(self)
What we're doing here is doing the pop in SecondViewController, and not passing any data, but since we've defined a protocol, we're going to use that in ViewController to handle the data.
So next, in ViewController, add the protocol you defined in SecondViewController to the list of classes ViewController inherits from:
class ViewController: UIViewController, SecondVCDelegate { ... your code... }
You'll need to add the function we defined in the new protocol in order to make the compiler happy. Inside of ViewController's class, add this:
func didFinishSecondVC(controller: SecondViewController) {
self.myBoolVar = true
controller.navigationController?.popViewControllerAnimated(true)
}
In SecondViewController where we're calling didFinishSecondVC, we're calling this method inside of the ViewController class, the controller we're popping to. It's similar to if we wrote this code inside of SecondViewController but we've written it inside of ViewController and we're using a delegate to manage the messaging between the two.
Finally, in ViewController, in the function we're targeting to push to SecondViewController, add this code:
let secondVC = secondViewController()
secondVC.delegate = self
self.navigationController?.pushViewController(secondVC, animated: true)
That's it! You should be all set to pass code between two view controllers without using storyboards!
_ = self.navigationController?.popViewController(animated: true)
let previousViewController = self.navigationController?.viewControllers.last as! PreviousViewController
previousViewController.PropertyOrMethod
I came across this while looking for a way to do it. Since I use Storyboards more often, I found that I can get the array of controllers in the navigation stack, get the one just before the current one that's on top, check to see if it's my delegate, and if so, cast it as the delegate, set my methods, then pop myself from the stack. Although the code is in ObjC, it should be easily translatable to swift:
// we need to get the previous view controller
NSArray *array = self.navigationController.viewControllers;
if ( array.count > 1) {
UIViewController *controller = [array objectAtIndex:(array.count - 2)];
if ( [controller conformsToProtocol:#protocol(GenreSelectionDelegate)]) {
id<GenreSelectionDelegate> genreDelegate = (id<GenreSelectionDelegate>)controller;
[genreDelegate setGenre:_selectedGenre];
}
[self.navigationController popViewControllerAnimated:YES];
}
Expanding upon the answer by Abdul Baseer Khan:
For cases where the current view controller may have been loaded by different types of previous view controller, we can use the safer as? call instead of as!, which will return nil if the controller is not what we were looking for:
let previousVC = self.navigationController?.viewControllers.last as? AnExampleController
previousVC?.doSomething()
Although, you would need to repeat that for each different view controller that could load the current view controller.
So, you may want to, instead, implement a protocol to be assigned to all the possible previous view controllers:
protocol PreviousController: UIViewController {
func doSomething()
}
class AnExampleController: UIViewController, PreviousController {
// ...
func doSomething() {}
}
class AnotherController: UIViewController, PreviousController {
// ...
func doSomething() {}
}
class CurrentController: UIViewController {
// ...
func goBack() {
let previousVC = self.navigationController?.viewControllers.last as? PreviousController
previousVC?.doSomething()
}
}