my application story board is as following
it is a tab bar controller based application with one of the tabs embedded in a navigation controller. when the user click on the first tab (view1) and click a button inside this view, he will be moved to view2. instead of using the back button to return to view1, I want the user to click on the tab item in order to return to view1 which works fine. However, I want to view an alert when the user clicks on the tab and he is in View2. I am using shouldSelectViewController and didSelectViewController delegate methods to check what tab is clicked and view the alert. The problem is that I can't reach View2 from these methods in the delegate to inform the application to view the alert only when user is in view2 and clicks the tab.
I tried to use this code inside shouldSelectViewController
if (tabBarController.selectedIndex == 0) {
NSLog(#"Delegate nav title: %#", tabBarController.selectedViewController.navigationItem.title);
}
these lines always return the title of view1
As they are in the same navigation controller, they have the same navigation item. Each view can configure this navigation item but it is generally the same object. That is why it returns the same title. Try setting up the navigation item title in second view controller's viewDidLoad method.
I finally found a solutino to my problem
first I added a static variable to View2 and called it inView2 as following
in View2.h
#interface
{}
+ ( BOOL ) isInQuizViewController;
+ ( void )setInQuizViewController:(BOOL)inQuizVal;
//...
#end
in View2.m
#implementation
static BOOL inView2 = NO;
+(BOOL)isInView2
{
return inView2;
}
+ ( void )setInView2:(BOOL)Val
{
inView2 = val;
}
these two methods are for setting and getting the value of inView2 which tells me whether or not the user is currently in View2
in View1.h create an IBAction associated with the button that will transmit from View1 to View2 and connect it to your storyboard
- (IBAction)GoToView2:(id)sender;
go to View1.m and import
#import "View2.h"
and implement your IBAction method to set the InView2 to YES
- (IBAction)GoToView2:(id)sender {
[View2 setInView2:YES];
}
then in the delegate.m
#import "View2.h"
#implementation AppDelegate
UITabBarController * _tabBarController;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
_tabBarController = (UITabBarController *)_window.rootViewController;
_tabBarController.delegate = self;
// Override point for customization after application launch.
return YES;
}
I defined a global _tabBarController and set it to _window.rootViewController and set its delegate to this delegate and remember to import "View2.h"
going to the ShouldSelectViewController method (note that this method is called before the transition to the selected tab ViewController, hence it is perfect for decision making of whether or not the selected tab viewController should be displayed to the user).
so in ShouldSelectViewController method I did the following
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController {
if(tabBarController.selectedIndex == 2)
{
if ([View2 isInView2]) {
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:#"alert"
message:#"are you sure you want to exit?"
delegate:self
cancelButtonTitle:#"Cancel"
otherButtonTitles:#"Yes",nil];
[alertView show];
return NO;
}
}
return YES;
}
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
if(buttonIndex == 1)
{//ok button pressed
// NSInteger destinationTabIdx = 2;
// UIView * fromView = tabBarController.selectedViewController.view;
// UIView * toView = [[[[[tabBarController.viewControllers objectAtIndex:destinationTabIdx] navigationController] viewControllers] objectAtIndex:0] view];
UINavigationController *nav = (UINavigationController *)_tabBarController.selectedViewController;
NSLog(#"vc title: %#",nav.title);
// [UIView transitionFromView:fromView toView:toView duration:0.8
// options: UIViewAnimationOptionTransitionNone
// completion:^(BOOL finished) {
// if (finished) {
// tabBarController.selectedIndex = destinationTabIdx;
// }
// }];
[nav popViewControllerAnimated:YES];
[QuizViewController setInQuizViewController:NO];
NSLog(#"app delegate transistion done");
}
}
Related
I had a requirement to cover the screen with black layout when the user moves the application to the background applicationDidEnterBackground in order to maintain the privacy of some sensitive datas on the screen. So for this i made use of AppDelegate function to present with a black color in background and then remove that by dismissing it when comes to foreground applicationDidEnterBackground. The code is:
#import "AppDelegate.h"
#interface AppDelegate ()
#end
#implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
return YES;
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
UIViewController *blankViewController = [UIViewController new];
blankViewController.view.backgroundColor = [UIColor blackColor];
[self.window makeKeyAndVisible];
[self.window.rootViewController presentViewController:blankViewController animated:NO completion:NULL];
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
[self.window.rootViewController dismissViewControllerAnimated:false completion:nil];
}
#end
Now in my application everything is working fine but in one screen i am presenting a ViewContollerB on a button click by using : [self presentViewController:webview animated:YES completion:nil]; The application as usually gets covered with black color when moving to background but when i take the application to foreground after this, then the presented ViewContollerB also gets dismissed . How to prevent my presented ViewController to get dismissed once coming from background?
Create a new 'UIViewController' called OverLayViewController and load it in
applicationDidEnterBackground method
- (void)applicationDidEnterBackground:(UIApplication *)application {
OverLayViewController *blankViewController = [OverLayViewController new];
blankViewController.view.backgroundColor = [UIColor blackColor];
[self.window makeKeyAndVisible];
UIViewController *rvc = self.window.rootViewController;
UIViewController *pvc = rvc.presentedViewController; // you may need to loop through presentedViewControllers if you have more than one
if(pvc != nil) {
[pvc presentViewController: blankViewController animated: NO completion:nil];
}
else{
[self.window.rootViewController presentViewController: blankViewController animated: NO completion:nil];
}
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
UIViewController *test = [self topViewController];
if ([test isKindOfClass:[OverLayViewController class]]) {
[test dismissViewControllerAnimated:false completion:nil];
}
}
- (UIViewController*)topViewController {
return [self topViewControllerWithRootViewController:[UIApplication sharedApplication].keyWindow.rootViewController];
}
-(UIViewController*)topViewControllerWithRootViewController:(UIViewController*)rootViewController {
if ([rootViewController isKindOfClass:[UITabBarController class]]) {
UITabBarController* tabBarController = (UITabBarController*)rootViewController;
return [self topViewControllerWithRootViewController:tabBarController.selectedViewController];
} else if ([rootViewController isKindOfClass:[UINavigationController class]]) {
UINavigationController* navigationController = (UINavigationController*)rootViewController;
return [self topViewControllerWithRootViewController:navigationController.visibleViewController];
} else if (rootViewController.presentedViewController) {
UIViewController* presentedViewController = rootViewController.presentedViewController;
return [self topViewControllerWithRootViewController:presentedViewController];
} else {
return rootViewController;
}
}
In this case, dismissViewContoller code wont apply for your webview.
You are trying to do the following: rootviewcontroller A presents a blank viewcontroller B. Your app goes into background, and you present viewcontroller C from there. Now B closes as A is presenting both B and C, and that is not allowed.
You will need to check if your rootviewcontroller is presenting any viewcontrollers, and if those are presenting any others recursively. You can check for those by using the property presentedViewController on a viewcontroller.
Personally, I would (in a base viewcontroller class that all viewcontrollers inherit from) keep a variable that checks if this one is visible (by keeping track of viewDidAppear and viewDidDisappear). If this is the one that is visible, you add a blank view on top.
Answer in Swift because I can't be trusted with Objective-C without an editor:
class BaseViewController: UIViewController {
var appeared = false
func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated: animated)
appeared = true
}
func viewDidDisappear(animated: Bool) {
super.viewDidDisappear(animated: animated)
appeared = false
}
}
Then you need to fire a notification from the AppDelegate that is caught in this viewcontroller, and then show a blank view on top.
I want to recreate the search UI shown in the iOS 7/8 calendar app. Presenting the search UI modally isn't a problem. I use UISearchController and modally present it just like the UICatalog sample code shows which gives me a nice drop down animation. The issue comes when trying to push a view controller from the results view controller. It isn't wrapped in a navigation controller so I can't push onto it. If I do wrap it in a navigation controller then I don't get the default drop down animation when I present the UISearchController. Any ideas?
EDIT:
I got it to push by wrapping my results view controller in a nav controller. However the search bar is still present after pushing the new VC onto the stack.
EDIT (2):
DTS from Apple said that the calendar app uses a non-standard method to push from search results. Instead they recommend removing focus from the search controller then pushing and returning focus on pop. This is similar to the way search in the settings app works I imagine.
Apple has gotten very clever there, but it's not a push, even though it looks like one.
They're using a custom transition (similar to what a navigation controller would do) to slide in a view controller which is embedded in a navigation controller.
You can spot the difference by slowly edge-swiping that detail view back and letting the previous view start to appear. Notice how the top navigation slides off to the right along with the details, instead of its bar buttons and title transitioning in-place?
Update:
The problem that you're seeing is that the search controller is presented above your navigation controller. As you discovered, even if you push a view controller onto a navigation controller's stack, the navigation bar is still beneath the search controller's presentation, so the search bar obscures any (pushed view controller's) navigation bar.
If you want to show results on top of the search controller without dismissing it, you'll need to present your own modal navigation view controller.
Unfortunately, there's no transition style which will let you present your navigation controller the same way the built-in push animation behaves.
As I can see, there are three effects that need to be duplicated.
The underlying content dims, as the presented view appears.
The presented view has a shadow.
The underlying content's navigation completely animates off-screen, but its content partially animates.
I've reproduced the general effect within an interactive custom modal transition. It generally mimic's Calendar's animation, but there are some differences (not shown), such as the keyboard (re)appearing too soon.
The modal controller that's presented is a navigation controller. I wired up a back button and edge swipe gesture to (interactively) dismiss it.
Here are the steps that are involved:
In your Storyboard, you would change the Segue type from Show Detail to Present Modally.
You can leave Presentation and Transition set to Default, as they'll need to be overridden in code.
In Xcode, add a new NavigationControllerDelegate file to your project.
NavigationControllerDelegate.h:
#interface NavigationControllerDelegate : NSObject <UINavigationControllerDelegate>
NavigationControllerDelegate.m:
#interface NavigationControllerDelegate () <UIViewControllerTransitioningDelegate>
#property (nonatomic, weak) IBOutlet UINavigationController *navigationController;
#property (nonatomic, strong) UIPercentDrivenInteractiveTransition* interactionController;
#end
- (void)awakeFromNib
{
UIScreenEdgePanGestureRecognizer *panGestureRecognizer = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget:self action:#selector(handlePan:)];
panGestureRecognizer.edges = UIRectEdgeLeft;
[self.navigationController.view addGestureRecognizer:panGestureRecognizer];
}
#pragma mark - Actions
- (void)handlePan:(UIScreenEdgePanGestureRecognizer *)gestureRecognizer
{
UIView *view = self.navigationController.view;
if (gestureRecognizer.state == UIGestureRecognizerStateBegan)
{
if (!self.interactionController)
{
self.interactionController = [UIPercentDrivenInteractiveTransition new];
[self.navigationController dismissViewControllerAnimated:YES completion:nil];
}
}
else if (gestureRecognizer.state == UIGestureRecognizerStateChanged)
{
CGFloat percent = [gestureRecognizer translationInView:view].x / CGRectGetWidth(view.bounds);
[self.interactionController updateInteractiveTransition:percent];
}
else if (gestureRecognizer.state == UIGestureRecognizerStateEnded)
{
CGFloat percent = [gestureRecognizer translationInView:view].x / CGRectGetWidth(view.bounds);
if (percent > 0.5 || [gestureRecognizer velocityInView:view].x > 50)
{
[self.interactionController finishInteractiveTransition];
}
else
{
[self.interactionController cancelInteractiveTransition];
}
self.interactionController = nil;
}
}
#pragma mark - <UIViewControllerAnimatedTransitioning>
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)__unused presented presentingController:(UIViewController *)__unused presenting sourceController:(UIViewController *)__unused source
{
TransitionAnimator *animator = [TransitionAnimator new];
animator.appearing = YES;
return animator;
}
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)__unused dismissed
{
TransitionAnimator *animator = [TransitionAnimator new];
return animator;
}
- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForPresentation:(id<UIViewControllerAnimatedTransitioning>)__unused animator
{
return nil;
}
- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id<UIViewControllerAnimatedTransitioning>)__unused animator
{
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wgnu-conditional-omitted-operand"
return self.interactionController ?: nil;
#pragma clang diagnostic pop
}
The delegate will provide the controller with its animator, interaction controller, and manage the screen edge pan gesture to dismiss the modal presentation.
In Storyboard, drag an Object (yellow cube) from the object library to the modal navigation controller. Set its class to ourNavigationControllerDelegate, and wire up its delegate and navigationController outlets to the storyboard's modal navigation controller.
In prepareForSegue from your search results controller, you'll need to set the modal navigation controller's transitioning delegate and modal presentation style.
navigationController.transitioningDelegate = (id<UIViewControllerTransitioningDelegate>)navigationController.delegate;
navigationController.modalPresentationStyle = UIModalPresentationCustom;
The custom animation that the modal presentation performs is handled by transition animator.
In Xcode, add a new TransitionAnimator file to your project.
TransitionAnimator.h:
#interface TransitionAnimator : NSObject <UIViewControllerAnimatedTransitioning>
#property (nonatomic, assign, getter = isAppearing) BOOL appearing;
TransitionAnimator.m:
#implementation TransitionAnimator
#synthesize appearing = _appearing;
#pragma mark - <UIViewControllerAnimatedTransitioning>
- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
return 0.3;
}
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
// Custom animation code goes here
}
The animation code is too long to provide within an answer, but it's available in a sample project which I've shared on GitHub.
Having said this, the code, as it stands, was more of a fun exercise. Apple has had years to refine and support all their transitions. If you adopt this custom animation, you may find cases (such as the visible keyboard) where the animation doesn't do what Apple's does. You'll have to decide whether you want to invest the time to improve the code to properly handle those cases.
I know this thread is old, but there seems to be a much simpler approach to getting the desired behavior.
The important thing to realize is the UISearchController is presented from the source controller, which is a view controller inside the navigation controller. If you inspect the view hierarchy, you see that the search controller, unlike regular modal presentations, isn't presented as a direct child of the window, but rather as a subview of the navigation controller.
So the general structure is
UINavigationController
MyRootViewController
UISearchViewController (presented pseudo-"modally")
MyContentController
Essentially you just need to get from the MyContentController up to the MyRootViewController, so you can access its navigationController property. In my tableView:didSelectRowAtIndexPath: method of my search content controller, I simply use the following to access my root view controller.
UINavigationController *navigationController = nil;
if ([self.parentViewController isKindOfClass:[UISearchController class]]) {
navigationController = self.parentViewController.presentingViewController.navigationController;
}
From there you can easily push something onto the navigation controller, and the animation is exactly what you'd expect.
EDIT: an alternate solution that doesn't rely on a UIWindow. I think the effect is very similar to the calendar app.
#interface SearchResultsController () <UINavigationControllerDelegate>
#end
#implementation SearchResultsController
- (void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// this will be the UINavigationController that provides the push animation.
// its rootViewController is a placeholder that exists so we can actually push and pop
UIViewController* rootVC = [UIViewController new]; // this is the placeholder
rootVC.view.backgroundColor = [UIColor clearColor];
UINavigationController* nc = [[UINavigationController alloc] initWithRootViewController: rootVC];
nc.modalPresentationStyle = UIModalPresentationCustom;
nc.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
[UIView transitionWithView: self.view.window
duration: 0.25
options: UIViewAnimationOptionTransitionCrossDissolve | UIViewAnimationOptionAllowAnimatedContent
animations: ^{
[self.parentViewController presentViewController: nc animated: NO completion: ^{
UIViewController* resultDetailViewController = [UIViewController alloc];
resultDetailViewController.title = #"Result Detail";
resultDetailViewController.view.backgroundColor = [UIColor whiteColor];
[nc pushViewController: resultDetailViewController animated: YES];
}];
}
completion:^(BOOL finished) {
nc.delegate = self;
}];
}
- (void) navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
// pop to root? then dismiss our window.
if ( navigationController.viewControllers[0] == viewController )
{
[UIView transitionWithView: self.view.window
duration: [CATransaction animationDuration]
options: UIViewAnimationOptionTransitionCrossDissolve | UIViewAnimationOptionAllowAnimatedContent
animations: ^{
[self.parentViewController dismissViewControllerAnimated: YES completion: nil];
}
completion: nil];
}
}
#end
ORIGINAL solution:
Here's my solution. I start out using the same technique you discovered in the UICatalog example for showing the search controller:
- (IBAction)search:(id)sender
{
SearchResultsController* searchResultsController = [self.storyboard instantiateViewControllerWithIdentifier: #"SearchResultsViewController"];
self.searchController = [[UISearchController alloc] initWithSearchResultsController:searchResultsController];
self.searchController.hidesNavigationBarDuringPresentation = NO;
[self presentViewController:self.searchController animated:YES completion: nil];
}
In my example, SearchResultsController is a UITableViewController-derived class. When a search result is tapped it creates a new UIWindow with a root UINavigationController and pushes the result-detail view controller to that. It monitors for the UINavigationController popping to root so it can dismiss the special UIWindow.
Now, the UIWindow isn't strictly required. I used it because it helps keep the SearchViewController visible during the push/pop transition. Instead, you could just present the UINavigationController from the UISearchController (and dismiss it from the navigationController:didShowViewController: delegate method). But modally-presented view controllers present on an opaque view by default, hiding what's underneath. You could address this by writing a custom transition that would be applied as the UINavigationController's transitioningDelegate.
#interface SearchResultsController () <UINavigationControllerDelegate>
#end
#implementation SearchResultsController
{
UIWindow* _overlayWindow;
}
- (void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// this will be the UINavigationController that provides the push animation.
// its rootViewController is a placeholder that exists so we can actually push and pop
UINavigationController* nc = [[UINavigationController alloc] initWithRootViewController: [UIViewController new]];
// the overlay window
_overlayWindow = [[UIWindow alloc] initWithFrame: self.view.window.frame];
_overlayWindow.rootViewController = nc;
_overlayWindow.windowLevel = self.view.window.windowLevel+1; // appear over us
_overlayWindow.backgroundColor = [UIColor clearColor];
[_overlayWindow makeKeyAndVisible];
// get this into the next run loop cycle:
dispatch_async(dispatch_get_main_queue(), ^{
UIViewController* resultDetailViewController = [UIViewController alloc];
resultDetailViewController.title = #"Result Detail";
resultDetailViewController.view.backgroundColor = [UIColor whiteColor];
[nc pushViewController: resultDetailViewController animated: YES];
// start looking for popping-to-root:
nc.delegate = self;
});
}
- (void) navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
// pop to root? then dismiss our window.
if ( navigationController.viewControllers[0] == viewController )
{
[_overlayWindow resignKeyWindow];
_overlayWindow = nil;
}
}
#end
As you present a viewController the navigationController becomes unavailable. So you have to dismiss your modal first and then push another viewController.
UISearchController must be rootViewController of a UINavigationController and then you present navigation controller as modal.
I have a trio of functions and a property that I use to control my popovers as follows:
-(void)dismissPopoverIfPresentAnimated:(BOOL)animated
{
if (self.currentPopover)
{
[self.currentPopover dismissPopoverAnimated:animated];
self.currentPopover = nil;
}
}
-(void)presentViewController:(UIViewController *)viewController inView:(UIView *)view fromRect:(CGRect)rect suppressArrow:(BOOL)suppressArrow
{
//Did the user just tap on a button to bring up the same controller that's already displayed?
//If so, just dismiss the current controller.
BOOL closeOnly = NO;
if (self.currentPopover)
{
UIViewController *currentController = [self.currentPopover.contentViewController isKindOfClass:UINavigationController.class] ? ((UINavigationController *)self.currentPopover.contentViewController).topViewController : self.currentPopover.contentViewController;
UIViewController *newController = [viewController isKindOfClass:UINavigationController.class] ? ((UINavigationController *)viewController).topViewController : viewController;
if ([currentController isKindOfClass:newController.class])
closeOnly = YES;
[self dismissPopoverIfPresentAnimated:NO];
}
if (!closeOnly)
{
self.currentPopover = [[UIPopoverController alloc] initWithContentViewController:viewController];
self.currentPopover.backgroundColor = [UIColor whiteColor];
[self.currentPopover presentPopoverFromRect:rect inView:view permittedArrowDirections:(suppressArrow ? 0 : UIPopoverArrowDirectionAny) animated:YES];
}
}
(instancetype) initWithContentViewController:(UIViewController )viewController
{
self = [super initWithContentViewController:[[UIViewController alloc] init]];
if (self)
{
UIViewController contentViewController = super.contentViewController;
[contentViewController addChildViewController:viewController];
[viewController didMoveToParentViewController:contentViewController];
[contentViewController.view addSubview:viewController.view];
[self setPopoverContentSize:viewController.preferredContentSize animated:NO];
}
return self;
}
This runs fine in iOS 7, but in iOS 8 the problem is there is a delay between the call to presentPopoverFromRect and when the item actually shows up onscreen. So, if a user double taps a button to show a popover, the first tap will properly dismiss, then "start" the showing of the new controller. The second tap will make the dismiss call (the popover is not yet visible) and then not show the new controller (this is a design feature so that click a button will show a popover, clicking it again will hide it).
The problem is that the call to dismiss the popover doesn't actually work and the popover will show up. At that point I can't get rid of it because my property is nil and I think it is not showing.
My guess is this is an iOS 8 bug where the dismiss somehow doesn't see a visible popover and thus doesn't do anything, where instead, it should prevent it from showing up.
Oh, one last note is that the call to presentViewController is always done on the main thread.
My app has four tabs 3 of them moves to a separate view controller . The fourth one enable the user to log out from the app what i need here is to add an alert message when the fourth tab is pressed can any one help me how to do so ?
I did search for solutions and found nothing .
Thanks in advance
first make sure your appdelegate.h file contains the UITabBarControllerDelegate to be able to access UITabBar methods .. so the definition of your AppDelegate.h should look like this
#interface AppDelegate : UIResponder <UIApplicationDelegate,UITabBarControllerDelegate >
then go to AppDelegeate.m and define a global boolean variable
bool shouldSelectViewController;
this variable decides whether or not your log in screen should be viewed or not .. although we are not going to manipulate this variable in the code but for some reason my code does not work as you wish without adding this variable it does not make any sense but xcode surprises me!
now add this method
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController {
if([viewController.title isEqualToString:#"your log in view controller title"]) {
//TODO show alert here
return shouldSelectViewController;
}
return YES;
}
}
then add a method to transform the user to the log in page if he confirms the alert
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
if(buttonIndex == 1) //here I assume that the alert has two buttons 0:cancel 1:Ok
{
// because you are in the AppDelegate you can't access the UITabBarController directly so you get it by writing this line of code
UITabBarController * tabBarController = (UITabBarController *)_window.rootViewController;
NSInteger destinationTabIdx = 3; //this is the index of the tab we want ot transfer the user to
UIView * fromView = tabBarController.selectedViewController.view; //move the user from current view he is in
UIView * toView = [[tabBarController.viewControllers objectAtIndex:destinationTabIdx] view]; // to this view which is view at tab index 3
//now do the transition to the view you want with optional animation
[UIView transitionFromView:fromView toView:toView duration:0.8
options:(destinationTabIdx > tabBarController.selectedIndex ? UIViewAnimationOptionTransitionFlipFromLeft: UIViewAnimationOptionTransitionFlipFromRight)
completion:^(BOOL finished) {
if (finished) {
tabBarController.selectedIndex = destinationTabIdx;
}
}];
}
}
Inside the forth viewController ViewWillappear method show the alertview.When ever it is shown the alert pops out
Use UITabBarControllerDelegate method:
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController {
if (tabBarController.selectedIndex == 3) {
//show alert here
}
-(void)viewWillAppear:(BOOL)animated
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Alert" message:#"
msg" delegate:self cancelButtonTitle:#"OK" otherButtonTitles:nil, nil];
[alert show];
}
//Delegate
- (void)alertView:(UIAlertView *)alertView willDismissWithButtonIndex: (NSInteger)buttonIndex
{
if(buttonIndex==0)
{
self.tabBarController.selectedIndex = 1;
//Move User to the FirstTabBarViewController
}
}
In Your ForthViewController method ViewWillappear use UIAlertView
It may be helpful
When you click the tabbar this method will be called so handle your logic in this method
- (void)tabBarController:(UITabBarController *)rootController didSelectViewController:(UIViewController *)viewController {
}
So if you want to show to the user an alert view when he/she taps on a tab bar item and you don't want to change to the corresponding view controller of the UITabBarItem then you should try this:
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController {
if([viewController isKindOfClass:[TheViewControllerOfYourAlertTab class]) {
//TODO show alert here
return NO;
}
return YES;
}
Also, if you want to show the ViewController of the UITabBar which will show the alert view after the user selects a button from the alert view, you will need an extra BOOL value to be added in the if statement something like:
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController {
if([viewController isKindOfClass:[TheViewControllerOfYourAlertTab class] && shouldShowAlert) {
//TODO show alert here
return NO;
}
return YES;
}
And the shouldShowAlert by default will be YES, when the user selects the required button from the alert view you can do:
shouldShowAlert = NO;
self.selectedIndex = indexOfYourAlertTabBarItem;
Also make sure to set the delegate of your alertView.
I may have some misunderstanding regarding the use of the UINavigationControllerDelegate protocol. Here is my situation:
I have a ViewController, let's call it, BViewController that may display a PopoverViewController. BViewController is the second ViewController in a NavigationContoller's stack, after AViewController. I need to dismiss the PopoverViewController when the user hits a button in BViewController and the app takes us back to the previous view--AViewController.
To do that, I have implemented the following in BViewController
- (void)viewWillDisappear:(BOOL)animated {
NSLog(#"BViewController will disappear");
// Check whether the popoverViewController is visible
if (self.popoverController.popoverVisible==YES) {
[self.popoverController dismissPopoverAnimated:NO];
}
}
However, that is not being called directly by the framework as BViewController is inside a NavigationController. Hence, I register a UINavigationControllerDelegate with my NavigationController and implement the following two methods:
- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
// Pass the message on to the viewController in question
[viewController viewWillAppear:animated];
}
- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
// Pass the message on to the viewController in question
[viewController viewWillDisappear:animated];
}
However, it seems that the passed in viewController parameter in both methods is the one that is about to be shown. I would have expected that the second method gives me access to the one that is about to disappear. So, when the user hits aforementioned button viewWillDisappear gets called on AViewController (which is about to be shown) and not on BViewController (which is about to disappear). Does that sound right? The apple documentation refers in both cases to
The view controller whose view and navigation item properties are being shown.
...which is not quite clear, I think. Thank you for some help, guys.
The two delegate method are both called for the same action (showing a view controller). The navigationController: willShowViewController:animated: is called before the new view controller is visible in the gui. The navigationController:navigationController didShowViewController:animated: is called after the new view controller is shown.
You will find this pattern in a lot of delegate protocols from apple. Unfortunately you do not have a delegate method in the NavigationViewController which tells you if the action was a pop or push.
I hook in my own protocol, which will know about the TO and FROM sides:
NavigationControllerDelegate.h:
#protocol NavigationControllerDelegate <NSObject>
#required
-(void) navigationController: (UINavigationController*) navController
willMoveFromViewController: (UIViewController*) from
toViewController: (UIViewController*) to;
#end
Instead of the regular UINavigationViewController, I then use a little helper class which keeps track of the view controllers:
NavigationHandler.h:
#interface NavigationHandler : NSObject <UINavigationControllerDelegate> {
NSMutableArray* m_viewControllers;
}
In my app delegate, I create one of these objects and set it as the delegate of the navigation controller:
...
m_navigationHandler = [[NavigationHandler alloc] init];
navigationController = [[UINavigationController alloc] initWithRootViewController: mainMenuViewController];
navigationController.delegate = m_navigationHandler;
...
And from then on its a simple case of comparing my own list of view controllers with what the navigation controller has:
NavigationHandler.m
#import "NavigationHandler.h"
#import "NavigationControllerDelegate.h"
#implementation NavigationHandler
-(id) init {
if ((self = [super init])) {
m_viewControllers = [[NSMutableArray alloc] init];
}
return self;
}
-(void) dealloc {
[m_viewControllers release];
[super dealloc];
}
- (void)navigationController:(UINavigationController *)navController
willShowViewController:(UIViewController *)viewController
animated:(BOOL)animated {
// Find out which viewControllers are disappearing and appearing
UIViewController* appearingViewController = nil;
UIViewController* disappearingViewController = nil;
if ([m_viewControllers count] < [navController.viewControllers count]) {
// pushing
if ([m_viewControllers count] > 0) {
disappearingViewController = [m_viewControllers lastObject];
}
appearingViewController = viewController;
[m_viewControllers addObject: viewController];
} else if ([m_viewControllers count] > [navController.viewControllers count]) {
// popping
disappearingViewController = [m_viewControllers lastObject];
appearingViewController = viewController;
[m_viewControllers removeLastObject];
} else {
return;
}
// Tell the view that will disappear
if (disappearingViewController != nil) {
if ([disappearingViewController conformsToProtocol: #protocol(NavigationControllerDelegate)]) {
if ([disappearingViewController respondsToSelector: #selector(navigationController:willMoveFromViewController:toViewController:)]) {
UIViewController<NavigationControllerDelegate>* vcDelegate = (UIViewController<NavigationControllerDelegate>*)disappearingViewController;
[vcDelegate navigationController: navController willMoveFromViewController: disappearingViewController toViewController: appearingViewController];
}
}
}
// Tell the view that will appear
if ([appearingViewController conformsToProtocol: #protocol(NavigationControllerDelegate)]) {
if ([appearingViewController respondsToSelector:#selector(navigationController:willMoveFromViewController:toViewController:)]) {
UIViewController<NavigationControllerDelegate>* vcDelegate = (UIViewController<NavigationControllerDelegate>*)appearingViewController;
[vcDelegate navigationController: navController willMoveFromViewController: disappearingViewController toViewController: appearingViewController];
}
}
}
#end