I am trying to add a new tabbar item in my tabbar, and when tapping the item, the viewcontroller connected to it, should be displayed fullscreen and as a modal.
I have connected the desired VC to the tabbar as a root (in order for it to be displayed in the tabbar).
I have tried the following code, but the VC is displayed as normal behaviour for a tabbar viewcontroller.
How can I make it show modally fullscreen instead?
class tabBarViewController: UITabBarController, UITabBarControllerDelegate {
override func viewDidLoad() {
super.viewDidLoad()
self.tabBarController?.delegate = self
}
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
let isModalView = viewController is dreamteamViewController
if isModalView {
// you can refactor this part of the code
let cameraController = UINavigationController(rootViewController: dreamteamViewController())
self.present(cameraController, animated: true, completion: nil)
return false
} else {
return true
}
}
Change your viewDidLoad like this to set the delegate callback to correct instance:
override func viewDidLoad() {
super.viewDidLoad()
self.delegate = self
}
Define and storyboard identifier for your desired viewcontroller in the story board
Change your shouldSelect method like below:
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool
{
let isModalView = viewController is DesiredViewController
if isModalView {
// you can refactor this part of the code
let mainStory = UIStoryboard(
name: "Main", bundle: nil
)
let desiredVC = mainStory.instantiateViewController(
withIdentifier:"YourIdentifier"
) as UIViewController
let navBar = UINavigationController.init(rootViewController: desiredVC)
self.present(navBar, animated: true, completion: nil)
return false
} else {
return true
}
}
I posted a project in my github that present one of the tabbar item modally. Please check it from https://github.com/Hbehboodi/Navigation-TabbarWithModalTabItem if any thing is not clear.
I have a UITabBarController. It has 4 tabBarItem.
Suppose I'm at 1st tabBarItem defaultViewController(1) and I
went to another ViewController(2) which is shown after some
actions in first defaultViewController(1).
Then I switched to 2nd tabBarItem defaultViewcontroller(2).
Again I switched back to 1st tabBarItem, it shows ViewController(2).
I want to show defaultViewController(1). How can I achieve this using swift 4.
defaultViewController(1) and defaultViewController(2) are the default ViewController for 1st and 2nd TabBarItem respectively.***
Let's say you have UINavigationController inside each tab of UITabBarController, and defaultViewController(1) is the rootViewController of your first tab, inside that there is a button that navigate to ViewController(2).
For this first of all, let's create generic solution. Create UIApplication Extension like this,
extension UIApplication {
class func topViewController(controller: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
if let navigationController = controller as? UINavigationController {
return topViewController(controller: navigationController.visibleViewController)
}
return controller
}
}
Implement UITabBarControllerDelegate in AppDelegate and do below code,
func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
if tabBarController.selectedIndex == 0 {
UIApplication.topViewController()?.navigationController?.popToRootViewController(animated: false)
}
}
In above code, I have taken tabBarController.selectedIndex to 0, you can make it different depending on your requirement.
Let me know in case of any queries.
Extend a subclass of UITabbarController and use it as your tabbar's class. In that implement UITabBarControllerDelegate, didSelect and use popToRootViewController to pop to your defaultViewController.
func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController){
if viewController is UINavigationController {
//when you have `UINavigationController`
let rootNavigationController = viewController as! UINavigationController
rootNavigationController.popToRootViewController(animated: false)
} else {
//when you don't have `UINavigationController` then dismiss all viewcontroller that was presented.
let rootViewController = viewController
if rootViewController.presentingViewController != nil {
rootViewController.dismiss(animated: false, completion: nil)
}
}
}
Note: add self.delegate = self to conform the protocol inside viewDidLoad method.
I can't delegate my custom Button. please help
1****TabBarController
func menuButtonAction(sender: UIButton) {
if let count = self.tabBar.items?.count {
let i = floor(Double(count / 2))
self.selectedViewController = self.viewControllers?[Int(i)]
}
}
2****ViewController
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
print(tabBarController.tabBarItem.title)
return true
}
don't print if i touch my custom Button. Another 4 buttons work OK
I am making an app that uses a tab bar to navigate between view controllers. I wanted to add a transition effect that would cross dissolve between each view when a tab button was pressed. I have implemented this transition with UIView.transitionFromView, however the navigation bar is not working as expected during the transition. During a transition to a view for the first time, the navigation bar is displayed too high, but jumps back into place once the transitions is complete. However, the next time you switch to the same view, the navigation bar is in the correct place during and after the transition.
I have seen an answer here to fix the problem for a custom animation, but I could not figure out how to get it to work with my current implementation.
MY Question
I have seen answers fixing the issue by forcing the view down by a few points (44 points), but is there a way to do it without directly changing the points? This might work the first time, but the issue resolves itself when any view is transitioned to a second time, thus making the view too low if you change the points.
Here is my code for the tab bar controller and the transition:
import UIKit
class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
override func viewDidLoad() {
super.viewDidLoad()
self.delegate = self
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
// Method used to detect when a tab bar button has been tapped
func tabBarController(tabBarController: UITabBarController, shouldSelectViewController viewController: UIViewController) -> Bool {
// Creating the 'to' and 'from' views for the transition
let fromView = tabBarController.selectedViewController!.view
let toView = viewController.view
if fromView == toView {
// If views are the same, then don't do a transition
return false
}
self.view.userInteractionEnabled = false
UIView.transitionFromView(fromView, toView: toView, duration: 2.0, options: .TransitionCrossDissolve, completion: nil)
self.view.userInteractionEnabled = true
return true
}
}
And here is what the issue looks like:
You can try with this code:
import UIKit
class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
override func viewDidLoad() {
super.viewDidLoad()
self.delegate = self
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
// Method used to detect when a tab bar button has been tapped
func tabBarController(tabBarController: UITabBarController, shouldSelectViewController viewController: UIViewController) -> Bool {
// Creating the 'to' and 'from' views for the transition
let fromView = tabBarController.selectedViewController!.view
let toView = viewController.view
if fromView == toView {
// If views are the same, then don't do a transition
return false
}
self.view.userInteractionEnabled = false
if let window = fromView.window {
let overlayView = UIScreen.mainScreen().snapshotViewAfterScreenUpdates(false)
viewController.view.addSubview(overlayView)
UIView.transitionFromView(fromView, toView: toView, duration: 2.0, options: .TransitionCrossDissolve, completion: { (finish) in
window.rootViewController = viewController
UIView.animateWithDuration(0.4, delay: 0.0, options: .TransitionCrossDissolve, animations: {
overlayView.alpha = 0
}, completion: { (finish) in
overlayView.removeFromSuperview()
})
})
}
self.view.userInteractionEnabled = true
return true
}
}
In my case, call toView.layoutIfNeeded() before the transition fixed the issue.
Tapping the tab bar icon for the current navigation controller already returns the user to the root view, but if they are scrolled way down, if they tap it again I want it to scroll to the top (same effect as tapping the status bar). How would I do this?
A good example is Instagram's feed, scroll down then tap the home icon in the tab bar to scroll back to top.
The scrolling back to the top is easy, but connecting it to the tab bar controller is what I'm stuck on.
Implement the UITabBarControllerDelegate method tabBarController:didSelectViewController: to be notified when the user selects a tab. This method is also called when the same tab button is tapped again, even if that tab is already selected.
A good place to implement this delegate would probably be your AppDelegate. Or the object that logically "owns" the tab bar controller.
I would declare and implement a method that can be called on your view controllers to scroll the UICollectionView.
- (void)tabBarController:(UITabBarController *)tabBarController
didSelectViewController:(UIViewController *)viewController
{
static UIViewController *previousController = nil;
if (previousController == viewController) {
// the same tab was tapped a second time
if ([viewController respondsToSelector:#selector(scrollToTop)]) {
[viewController scrollToTop];
}
}
previousController = viewController;
}
SWIFT 3
Here goes..
First implement the UITabBarControllerDelegate in the class and make sure the delegate is set in viewDidLoad
class DesignStoryStreamVC: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, UITabBarControllerDelegate {
#IBOutlet weak var collectionView: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
self.tabBarController?.delegate = self
collectionView.delegate = self
collectionView.dataSource = self
}
}
Next, put this delegate function somewhere in your class.
func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
let tabBarIndex = tabBarController.selectedIndex
print(tabBarIndex)
if tabBarIndex == 0 {
self.collectionView.setContentOffset(CGPoint.zero, animated: true)
}
}
Make sure to select the correct index in the "if" statement. I included the print function so you can double check.
Swift 5: no need for stored properties in the UITabBarController.
In MyTabBarController.swift, implement tabBarController(_:shouldSelect) to detect when the user re-selects the tab bar item:
protocol TabBarReselectHandling {
func handleReselect()
}
class MyTabBarController: UITabBarController, UITabBarControllerDelegate {
override func viewDidLoad() {
super.viewDidLoad()
delegate = self
}
func tabBarController(
_ tabBarController: UITabBarController,
shouldSelect viewController: UIViewController
) -> Bool {
if tabBarController.selectedViewController === viewController,
let handler = viewController as? TabBarReselectHandling {
// NOTE: viewController in line above might be a UINavigationController,
// in which case you need to access its contents
handler.handleReselect()
}
return true
}
}
In MyTableViewController.swift, handle the re-selection by scrolling the table view to the top:
class MyTableViewController: UITableViewController, TabBarReselectHandling {
func handleReselect() {
tableView?.setContentOffset(.zero, animated: true)
}
}
Now you can easily extend this to other tabs by just implementing TabBarReselectHandling.
You can use shouldSelect rather than didSelect, which would omit the need for an external variable to keep track of the previous view controller.
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
{
if ([viewController isEqual:self] && [tabBarController.selectedViewController isEqual:viewController]) {
// Do custom stuff here
}
return YES;
}
extension UIViewController {
func scrollToTop() {
func scrollToTop(view: UIView?) {
guard let view = view else { return }
switch view {
case let scrollView as UIScrollView:
if scrollView.scrollsToTop == true {
scrollView.setContentOffset(CGPoint(x: 0.0, y: -scrollView.contentInset.top), animated: true)
return
}
default:
break
}
for subView in view.subviews {
scrollToTop(view: subView)
}
}
scrollToTop(view: self.view)
}
}
This is my answer in Swift 3. It uses a helper function for recursive calls and it automatically scrolls to top on call. Tested on a UICollectionViewController embedded into a UINavigationController embedded in a UITabBarController
I was using this View hierarchy.
UITabBarController > UINavigationController > UIViewController
I got a reference to the UITabBarController in the UIViewController
tabBarControllerRef = self.tabBarController as! CustomTabBarClass
tabBarControllerRef!.navigationControllerRef = self.navigationController as! CustomNavigationBarClass
tabBarControllerRef!.viewControllerRef = self
Then I created a Bool that was called at the correct times, and a method that allows scrolling to top smoothly
var canScrollToTop:Bool = true
// Called when the view becomes available
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
canScrollToTop = true
}
// Called when the view becomes unavailable
override func viewWillDisappear(animated: Bool) {
super.viewWillDisappear(animated)
canScrollToTop = false
}
// Scrolls to top nicely
func scrollToTop() {
self.collectionView.setContentOffset(CGPoint(x: 0, y: 0), animated: true)
}
Then in my UITabBarController Custom Class I called this
func tabBarController(tabBarController: UITabBarController, didSelectViewController viewController: UIViewController) {
// Allows scrolling to top on second tab bar click
if (viewController.isKindOfClass(CustomNavigationBarClass) && tabBarController.selectedIndex == 0) {
if (viewControllerRef!.canScrollToTop) {
viewControllerRef!.scrollToTop()
}
}
}
The Result is identical to Instagram and Twitter's feed :)
Swift 3 approach::
//MARK: Properties
var previousController: UIViewController?
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
if self.previousController == viewController || self.previousController == nil {
// the same tab was tapped a second time
let nav = viewController as! UINavigationController
// if in first level of navigation (table view) then and only then scroll to top
if nav.viewControllers.count < 2 {
let tableCont = nav.topViewController as! UITableViewController
tableCont.tableView.setContentOffset(CGPoint(x: 0.0, y: -tableCont.tableView.contentInset.top), animated: true)
}
}
self.previousController = viewController;
return true
}
A few notes here::
"shouldSelect" instead of "didSelect" because the latter is taking place after transition, meaning viewController local var already changed.
2. We need to handle the event before changing controller, in order to have the information of navigation's view controllers regarding scrolling (or not) action.
Explanation:: We want to scroll to top, if current view is actually a List/Table view controller. If navigation has advanced and we tap same tab bar, desired action would be to just pop one step (default functionality) and not scroll to top. If navigation hasn't advanced meaning we are still in table/list controller then and only then we want to scroll to top when tapping again. (Same thing Facebook does when tapping "Feed" from a user's profile. It only goes back to feed without scrolling to top.
In this implementation you no need static variable and previous view controller state
If your UITableViewController in UINavigationController you can implement protocol and function:
protocol ScrollableToTop {
func scrollToTop()
}
extension UIScrollView {
func scrollToTop(_ animated: Bool) {
var topContentOffset: CGPoint
if #available(iOS 11.0, *) {
topContentOffset = CGPoint(x: -safeAreaInsets.left, y: -safeAreaInsets.top)
} else {
topContentOffset = CGPoint(x: -contentInset.left, y: -contentInset.top)
}
setContentOffset(topContentOffset, animated: animated)
}
}
Then in your UITableViewController:
class MyTableViewController: UITableViewController: ScrollableToTop {
func scrollToTop() {
if isViewLoaded {
tableView.scrollToTop(true)
}
}
}
Then in UITabBarControllerDelegate:
extension MyTabBarController: UITabBarControllerDelegate {
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
guard tabBarController.selectedViewController === viewController else { return true }
guard let navigationController = viewController as? UINavigationController else {
assertionFailure()
return true
}
guard
navigationController.viewControllers.count <= 1,
let destinationViewController = navigationController.viewControllers.first as? ScrollableToTop
else {
return true
}
destinationViewController.scrollToTop()
return false
}
}
I have a collection view embedded in a navigation controller, in Swift this works.
var previousController: UIViewController?
func tabBarController(tabBarController: UITabBarController, didSelectViewController viewController: UIViewController) {
if previousController == viewController {
if let navVC = viewController as? UINavigationController, vc = navVC.viewControllers.first as? UICollectionViewController {
vc.collectionView?.setContentOffset(CGPointZero, animated: true)
}
}
previousController = viewController;
}
I've implemented a plug & play UITabBarController that you can freely re-use in your projects. To enable the scroll-to-top functionality, you should just have to use the subclass, nothing else.
Should work out of the box with Storyboards also.
Code:
/// A UITabBarController subclass that allows "scroll-to-top" gestures via tapping
/// tab bar items. You enable the functionality by simply subclassing.
class ScrollToTopTabBarController: UITabBarController, UITabBarControllerDelegate {
/// Determines whether the scrolling capability's enabled.
var scrollEnabled: Bool = true
private var previousIndex = 0
override func viewDidLoad() {
super.viewDidLoad()
delegate = self
}
/*
Always call "super" if you're overriding this method in your subclass.
*/
func tabBarController(tabBarController: UITabBarController, didSelectViewController viewController: UIViewController) {
guard scrollEnabled else {
return
}
guard let index = viewControllers?.indexOf(viewController) else {
return
}
if index == previousIndex {
dispatch_async(dispatch_get_global_queue(QOS_CLASS_USER_INITIATED, 0), { [weak self] () in
guard let scrollView = self?.iterateThroughSubviews(self?.view) else {
return
}
dispatch_async(dispatch_get_main_queue(), {
scrollView.setContentOffset(CGPointZero, animated: true)
})
})
}
previousIndex = index
}
/*
Iterates through the view hierarchy in an attempt to locate a UIScrollView with "scrollsToTop" enabled.
Since the functionality relies on "scrollsToTop", it plugs easily into existing architectures - you can
control the behaviour by modifying "scrollsToTop" on your UIScrollViews.
*/
private func iterateThroughSubviews(parentView: UIView?) -> UIScrollView? {
guard let view = parentView else {
return nil
}
for subview in view.subviews {
if let scrollView = subview as? UIScrollView where scrollView.scrollsToTop == true {
return scrollView
}
if let scrollView = iterateThroughSubviews(subview) {
return scrollView
}
}
return nil
}
}
Edit (09.08.2016):
After attempting to compile with the default Release configuration (archiving) the compiler would not allow the possibility of creating a large number of closures that were captured in a recursive function, thus it would not compile. Changed out the code to return the first found UIScrollView with "scrollsToTop" set to true without using closures.
I tried the solution given by #jsanabria. This worked well on a fixed tableview, but it wouldn't work for my infinite scroll tableview. It only came up the table view about halfway after loading the new scrolling data.
Swift 5.0+
self.tableView.scrollToRow(at: IndexPath.init(row: 0, section: 0), at: UITableView.ScrollPosition(rawValue: 0)!, animated: true)
TESTED SOLUTION IN SWIFT
STEP 1
In your main tabbarcontroller class declare
weak static var previousController: UIViewController?
STEP 2
In viewdidLoad() set
MainTabBarViewController.previousController = viewControllers?[0]
STEP 3
extension MainTabBarViewController: UITabBarControllerDelegate {
func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
if MainTabBarViewController.previousController == viewController {
/// here comes your code
}
MainTabBarViewController.previousController = viewController
}
}
I found the scrollRectToVisible method works better than the setContentOffset.
Swift:
After you catch the click on the tab bar from the delegate, something like below:
func tabBarController(tabBarController: UITabBarController, didSelectViewController viewController: UIViewController) {
if (viewController.isKindOfClass(SomeControllerClass) && tabBarController.selectedIndex == 0)
{
viewController.scrollToTop()
}
}
Now for the scrollToTop function inside the controller:
func scrollToTop()
{
self.tableView.scrollRectToVisible(CGRectMake(0,0,CGRectGetWidth(self.tableView.frame), CGRectGetHeight(self.tableView.frame)), animated: true)
}