I am new to iPad development. I know how to use images for Page view controller. My problem is i have 3 charts which i have done in three view controllers.. How can i combine all the view controllers in a single page view controller. I have for now kept three view controllers.
I have tried lot of tutorials but none explains me how to use three view controllers
I have done like this now but this is wrong
-(IBAction)handleSwipeLeft:(UISwipeGestureRecognizer*)sender {
LastLearningSessionViewController *last=[[LastLearningSessionViewController alloc]init];
[self presentViewController:last animated:YES completion:nil];
}
From what I can see it appears you may have done this slightly wrong.
First you need to create a controller for the UIPageViewController, that is a datasource and delegate.
Please note all code has been written directly to the answer and has not been tested.
MyUIPageViewController.h
#interface
MyUIPageViewController : UIViewController <UIPageViewControllerDataSource, UIPageViewControllerDelegate>
{
NSNumber *currentIndex //Using NSNumber to handle 32bit/64bit easier.
}
#property (nonatomic, strong) UIPageViewController *pageViewController
#property (nonatomic, strong) NSArray *controllersArray //Used to help navigate between controllers
#end
MyUIPageViewController.m
#import MyUIPageViewController.h
#implementation MyUIPageViewController
- (instancetype)initWithNibName:(NSString *)nibName
bundle:(NSBundle *)nibBundle
{
if(self = [super initWithNibName:nibName bundle:nibBundle])
{
//Create ChartViewController1 (UIViewController *ChartViewController1 = [[ChartViewController1Class alloc] init];)
//Create ChartViewController2
//Create ChartViewController3
//Now we have created all 3 chartViewControllers, create our controllers Array with the controller objects.
self.controllersArray = [[NSArray alloc] initWithObjects:ChartViewController1, ChartViewController2, ChartViewController3];
//Currently setting to 0. A proper way of handling with Multi-tasking is to store the index value from before, but not dealing with that right now.
currentIndex = [NSNumber numberWithInt:0];
//Create our PageViewController. Currently set to PageCurl and all pages will go from left to right.
//These options can be changed, if so desired (Scroll Effect like iBooks Textbooks and a page change from bottom to top like a flip book.
self.pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStylePageCurl navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil];
//Set ourselves as the datasource and delegate to handle the pages etc.
self.pageViewController.datasource = self;
self.pageViewController.delegate = self;
//We need to set the viewControllers for the PageViewController, because this is the initial load, we will not animate the change.
[self.pageViewController setViewControllers:self.controllersArray direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:^ (BOOL finished) {
//No animation is being done so no need to worry.
}];
//Set our view to be the pagecontroller's view, so we can see it all.
self.view = self.pageViewController.view;
}
return self;
}
//DataSource Methods:
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController
viewControllerBeforeViewController:(UIViewController *)viewController
{
//As this method looks for the previous view controller. If our current index is 0, there is no previous VC. But using the objectAtIndex method on the array would throw a outOfRange exception
if([self.currentIndex intValue] <= 0)
{
return nil;
}
else
{
return [self.controllersArray objectAtIndex:([self.currentIndex intValue] - 1)];
}
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController
viewControllerAfterViewController:(UIViewController *)viewController
{
//As this method looks for the next view controller. If our current index is the maximum value the array count and be (2), there isn't a new VC to push. But using the objectAtIndex method on the array would throw a outOfRange exception
if([self.currentIndex intValue] >= self.controllersArray.count)
{
return nil;
}
else
{
return [self.controllersArray objectAtIndex:([self.currentIndex intValue] + 1)];
}
}
//Delegate Methods
- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
if(transitionCompleted)
{
//We will update our currentIndex, only if the transition has happened.
switch (previousViewControllers)
{
case 0:
//Something went wrong :S
break;
case 1:
//We are either in Vertical Orientation of the first viewController is only being shown.
if([pageViewController.viewControllers contains:[self.controllersArray objectAtIndex:([currentIndex intValue]+ 1)]])
{
currentIndex = [NSNumber numberWithInt:([currentIndex intValue] + 1)];
}
else
{
if([currentIndex intValue] == 0)
{
//Saftey Net.
}
else
{
currentIndex = [NSNumber numberWithInt:([currentIndex intValue] - 1)];
}
}
break;
case 2:
//We are in horizontal Orientation.
//With 3 View Controllers the only ViewController that will be in both arrays is the ViewController at index 1. We just need to see if the pageViewControllers viewcontrollers array contains the ViewController at index 0 or index 1.
if([pageViewController.viewControllers contains:[self.controllersArray objectAtIndex:([currentIndex intValue]+ 1)]])
{
currentIndex = [NSNumber numberWithInt:([currentIndex intValue] + 1)];
}
else
{
if([currentIndex intValue] == 0)
{
//Saftey Net.
}
else
{
currentIndex = [NSNumber numberWithInt:([currentIndex intValue] - 1)];
}
}
break;
default:
//Should never reach here.
break;
}
}
}
#end
It is also handy to look at the reference documentation:
Class Reference - Apple Docs
is there a way to programmatically tell when a certain page is showing in a pageviewcontroller? For example, I instantiated it as the following:
if (index == 0) {
pageContentViewController = [storyboard instantiateViewControllerWithIdentifier:#"OnCampusTable"];
}
else if (index == 1) {
pageContentViewController = [storyboard instantiateViewControllerWithIdentifier:#"OffCampusTable"];
}
else if (index == 2) {
pageContentViewController = [storyboard instantiateViewControllerWithIdentifier:#"MyEventsTable"];
}
I want to write something where
if (current page is "OnCampusTable") {
method 1
}
else if (current page is "OffCampusTable") {
method 2
}
else if (current page is "MyEventsTable") {
method 3
}
I've tried using the index, but because of the way that the pages load and stuff, it actually doesn't work properly. I was thinking of trying to access the page indicator thing (the little circle things) to get the page number, but I don't know how to do that.
I've seen a few solutions out there that use an array of ViewControllers and do comparisons, but I don't want to keep a bunch of controllers around (I generate them on the fly from my model), so I found a solution that seems to work.
Basically I point a property to the prior and next controllers in the data source before and after methods. In the delegate's didFinishAnimating call I compare the new controller to these properties to see if we moved forward or backward. One caveat is that before and after don't get called if the controller has already been loaded, so I reassign my property based on didFinishAnimating's previousViewController's value.
Note, I only implemented this for the case where one page is displayed.
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
if (self.pageIndex > 0) {
UIViewController *vc = [self genController:self.trackList[self.pageIndex - 1]];
self.priorVC = vc;
return vc;
} else {
self.priorVC = nil;
return nil;
}
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
if (self.pageIndex < self.trackList.count - 1) {
UIViewController *vc = [self genController:self.trackList[self.pageIndex + 1]];
self.nextVC = vc;
return vc;
} else {
self.nextVC = nil;
return nil;
}
}
- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
if (finished && completed) {
if (pageViewController.viewControllers.lastObject == self.priorVC) {
NSLog(#"Back");
self.pageIndex--;
self.nextVC = previousViewControllers.lastObject;
} else if (pageViewController.viewControllers.lastObject == self.nextVC) {
NSLog(#"Forward");
self.pageIndex++;
self.priorVC = previousViewControllers.lastObject;
}
NSLog(#"Page: %ld",self.pageIndex);
}
}
You can use the delegate method pageViewController:didFinishAnimating:previousViewControllers:transitionCompleted: to keep track of the current page and then execute some method depending on the page.
is there anyway to check if a specific instance of a class has already been created. I feel like it is hard to check if the instance already exists when there is a chance you may not have created it yet.
Here is my code:
-(IBAction)done:(id)sender
{ //I want to figure out how to check if 'newWindow' already exists before I create another 'newWindow'
SimpleTableView *newWindow = [self.storyboard instantiateViewControllerWithIdentifier:#"SimpleTableView"];
[self.navigationController pushViewController:newWindow animated:YES];
}
Thanks for all the help guys.
Yes, there is a simple way to do it.
You just need to have some reference to it (for example create a property) and check whether it is nil (not initialized) or not. You can do it like this:
if(!myReference){
//if you get here it means that it hasn't been initialized yet so you have to do it
}
First make newWindow an ivar or a property.
Then:
if (!newWindow){
newWindow = [self.storyboard instantiateViewControllerWithIdentifier:#"SimpleTableView"];
}
I wrote you a method that checks all viewControllers in UINavigationController:
- (BOOL)classExistsInNavigationController:(Class)class
{
for (UIViewController *controller in self.navigationController.viewControllers)
{
if ([controller isKindOfClass:class])
{
return YES;
}
}
return NO;
}
Use it like this:
- (IBAction)done:(id)sender
{
//I want to figure out how to check if 'newWindow' already exists before I create another newWindow
if (![self classExistsInNavigationController:[SimpleTableView class]])
{
SimpleTableView *newWindow = [self.storyboard instantiateViewControllerWithIdentifier:#"SimpleTableView"];
[self.navigationController pushViewController:newWindow animated:YES];
}
}
You can also do something like this:
- (UIViewController *)classExistsInNavigationController:(Class)class
{
for (UIViewController *controller in self.navigationController.viewControllers)
{
if ([controller isKindOfClass:class])
{
return controller;
}
}
return nil;
}
And use it like this if you want to pop to the viewController that exists already:
- (IBAction)done:(id)sender
{
//I want to figure out how to check if 'newWindow' already exists before I create another newWindow
UIViewController *controller = [self classExistsInNavigationController:[SimpleTableView class]];
if (!controller)
{
SimpleTableView *newWindow = [self.storyboard instantiateViewControllerWithIdentifier:#"SimpleTableView"];
[self.navigationController pushViewController:newWindow animated:YES];
}
else
{
[self.navigationController popToViewController:controller animated:YES];
}
}
You can use if/else to check newWindow exists or not.
if (newWindow) { // newWindow is exist to do something
// Do something.
} else { // newWindow is not exist to do something
// Do something.
}
You can implement an instance counter (https://stackoverflow.com/a/30509753/4647396) in the class you want to track.
Then just check if the counter is greater than 0.
If I interpret your question correctly you just want to know wether an instance exists and dont need a reference to it.
I've built a custom UITabBarController with Storyboards/Segues and UIViewController containment. Here is a link to it: https://github.com/mhaddl/MHCustomTabBarController
The UIViewControllers which will be presented by the Container are stored in a NSMutableDictionary (keys are the segues' identifiers). Everything is working fine until the point is reached where I come back to a earlier presented ViewController. At this moment "dealloc" gets called on this ViewController before it is presented.
How can I prevent "dealloc" from getting called so it can be used to unsubscribe from Notifications, and nil delegates.
MHCustomTabBarController:
#implementation MHCustomTabBarController {
NSMutableDictionary *_viewControllersByIdentifier;
}
- (void)viewDidLoad {
[super viewDidLoad];
_viewControllersByIdentifier = [NSMutableDictionary dictionary];
}
-(void) viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
if (self.childViewControllers.count < 1) {
[self performSegueWithIdentifier:#"viewController1" sender:[self.buttons objectAtIndex:0]];
}
}
- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration {
self.destinationViewController.view.frame = self.container.bounds;
}
#pragma mark - Segue
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if (![segue isKindOfClass:[MHTabBarSegue class]]) {
[super prepareForSegue:segue sender:sender];
return;
}
self.oldViewController = self.destinationViewController;
//if view controller isn't already contained in the viewControllers-Dictionary
if (![_viewControllersByIdentifier objectForKey:segue.identifier]) {
[_viewControllersByIdentifier setObject:segue.destinationViewController forKey:segue.identifier];
}
for (UIButton *aButton in self.buttons) {
[aButton setSelected:NO];
}
UIButton *button = (UIButton *)sender;
[button setSelected:YES];
self.destinationIdentifier = segue.identifier;
self.destinationViewController = [_viewControllersByIdentifier objectForKey:self.destinationIdentifier];
}
- (BOOL)shouldPerformSegueWithIdentifier:(NSString *)identifier sender:(id)sender {
if ([self.destinationIdentifier isEqual:identifier]) {
//Dont perform segue, if visible ViewController is already the destination ViewController
return NO;
}
return YES;
}
#pragma mark - Memory Warning
- (void)didReceiveMemoryWarning {
[[_viewControllersByIdentifier allKeys] enumerateObjectsUsingBlock:^(NSString *key, NSUInteger idx, BOOL *stop) {
if (![self.destinationIdentifier isEqualToString:key]) {
[_viewControllersByIdentifier removeObjectForKey:key];
}
}];
}
#end
MHTabBarSegue:
#implementation MHTabBarSegue
- (void) perform {
MHCustomTabBarController *tabBarViewController = (MHCustomTabBarController *)self.sourceViewController;
UIViewController *destinationViewController = (UIViewController *) tabBarViewController.destinationViewController;
//remove old viewController
if (tabBarViewController.oldViewController) {
[tabBarViewController.oldViewController willMoveToParentViewController:nil];
[tabBarViewController.oldViewController.view removeFromSuperview];
[tabBarViewController.oldViewController removeFromParentViewController];
}
destinationViewController.view.frame = tabBarViewController.container.bounds;
[tabBarViewController addChildViewController:destinationViewController];
[tabBarViewController.container addSubview:destinationViewController.view];
[destinationViewController didMoveToParentViewController:tabBarViewController];
}
#end
"At this moment "dealloc" gets called on this ViewController before it is presented." -- no, not really. Dealloc is being called on a controller that never gets on screen, not the one you came from initially or are going back to. The way your segue is set up, and the fact that you keep a reference to your controllers in the dictionary, means that they never get deallocated. Segues (other than unwinds) ALWAYS instantiate new view controllers, so what's happening is that a new instance of, say VC1 is created when you click on the first tab (and a segue is triggered), but you never do anything with that controller (which would be self.destinationViewController in the custom segue class) so it's deallocated as soon as the perform method exits.
Depending on where you setup any delegates or notification observers, this might not be a problem -- this controller that's created, and then immediately deallocated never has its viewDidLoad method called, so if you do those things in viewDidLoad, they won't ever happen for this transient view controller.
If you don't want this to happen, then you need to make your transitions in code without using segues.
Is there a built-in way to get from a UIView to its UIViewController? I know you can get from UIViewController to its UIView via [self view] but I was wondering if there is a reverse reference?
Using the example posted by Brock, I modified it so that it is a category of UIView instead UIViewController and made it recursive so that any subview can (hopefully) find the parent UIViewController.
#interface UIView (FindUIViewController)
- (UIViewController *) firstAvailableUIViewController;
#end
#implementation UIView (FindUIViewController)
- (UIViewController *) firstAvailableUIViewController {
UIResponder *responder = [self nextResponder];
while (responder != nil) {
if ([responder isKindOfClass:[UIViewController class]]) {
return (UIViewController *)responder;
}
responder = [responder nextResponder];
}
return nil;
}
#end
To use this code, add it into an new class file (I named mine "UIKitCategories") and remove the class data... copy the #interface into the header, and the #implementation into the .m file. Then in your project, #import "UIKitCategories.h" and use within the UIView code:
// from a UIView subclass... returns nil if UIViewController not available
UIViewController * myController = [self firstAvailableUIViewController];
UIView is a subclass of UIResponder. UIResponder lays out the method -nextResponder with an implementation that returns nil. UIView overrides this method, as documented in UIResponder (for some reason instead of in UIView) as follows: if the view has a view controller, it is returned by -nextResponder. If there is no view controller, the method will return the superview.
Add this to your project and you're ready to roll.
#interface UIView (APIFix)
- (UIViewController *)viewController;
#end
#implementation UIView (APIFix)
- (UIViewController *)viewController {
if ([self.nextResponder isKindOfClass:UIViewController.class])
return (UIViewController *)self.nextResponder;
else
return nil;
}
#end
Now UIView has a working method for returning the view controller.
Since this has been the accepted answer for a long time, I feel I need to rectify it with a better answer.
Some comments on the need:
Your view should not need to access the view controller directly.
The view should instead be independent of the view controller, and be able to work in different contexts.
Should you need the view to interface in a way with the view controller, the recommended way, and what Apple does across Cocoa is to use the delegate pattern.
An example of how to implement it follows:
#protocol MyViewDelegate < NSObject >
- (void)viewActionHappened;
#end
#interface MyView : UIView
#property (nonatomic, assign) MyViewDelegate delegate;
#end
#interface MyViewController < MyViewDelegate >
#end
The view interfaces with its delegate (as UITableView does, for instance) and it doesn't care if its implemented in the view controller or in any other class that you end up using.
My original answer follows: I don't recommend this, neither the rest of the answers where direct access to the view controller is achieved
There is no built-in way to do it. While you can get around it by adding a IBOutlet on the UIView and connecting these in Interface Builder, this is not recommended. The view should not know about the view controller. Instead, you should do as #Phil M suggests and create a protocol to be used as the delegate.
I would suggest a more lightweight approach for traversing the complete responder chain without having to add a category on UIView:
#implementation MyUIViewSubclass
- (UIViewController *)viewController {
UIResponder *responder = self;
while (![responder isKindOfClass:[UIViewController class]]) {
responder = [responder nextResponder];
if (nil == responder) {
break;
}
}
return (UIViewController *)responder;
}
#end
Combining several already given answers, I'm shipping on it as well with my implementation:
#implementation UIView (AppNameAdditions)
- (UIViewController *)appName_viewController {
/// Finds the view's view controller.
// Take the view controller class object here and avoid sending the same message iteratively unnecessarily.
Class vcc = [UIViewController class];
// Traverse responder chain. Return first found view controller, which will be the view's view controller.
UIResponder *responder = self;
while ((responder = [responder nextResponder]))
if ([responder isKindOfClass: vcc])
return (UIViewController *)responder;
// If the view controller isn't found, return nil.
return nil;
}
#end
The category is part of my ARC-enabled static library that I ship on every application I create. It's been tested several times and I didn't find any problems or leaks.
P.S.: You don't need to use a category like I did if the concerned view is a subclass of yours. In the latter case, just put the method in your subclass and you're good to go.
I modified de answer so I can pass any view, button, label etc. to get it's parent UIViewController. Here is my code.
+(UIViewController *)viewController:(id)view {
UIResponder *responder = view;
while (![responder isKindOfClass:[UIViewController class]]) {
responder = [responder nextResponder];
if (nil == responder) {
break;
}
}
return (UIViewController *)responder;
}
Edit Swift 3 Version
class func viewController(_ view: UIView) -> UIViewController {
var responder: UIResponder? = view
while !(responder is UIViewController) {
responder = responder?.next
if nil == responder {
break
}
}
return (responder as? UIViewController)!
}
Edit 2:- Swift Extention
extension UIView
{
//Get Parent View Controller from any view
func parentViewController() -> UIViewController {
var responder: UIResponder? = self
while !(responder is UIViewController) {
responder = responder?.next
if nil == responder {
break
}
}
return (responder as? UIViewController)!
}
}
Even though this can technically be solved as pgb recommends, IMHO, this is a design flaw. The view should not need to be aware of the controller.
Don't forget that you can get access to the root view controller for the window that the view is a subview of. From there, if you are e.g. using a navigation view controller and want to push a new view onto it:
[[[[self window] rootViewController] navigationController] pushViewController:newController animated:YES];
You will need to set up the rootViewController property of the window properly first, however. Do this when you first create the controller e.g. in your app delegate:
-(void) applicationDidFinishLaunching:(UIApplication *)application {
window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
RootViewController *controller = [[YourRootViewController] alloc] init];
[window setRootViewController: controller];
navigationController = [[UINavigationController alloc] initWithRootViewController:rootViewController];
[controller release];
[window addSubview:[[self navigationController] view]];
[window makeKeyAndVisible];
}
I stumbled upon a situation where I have a small component I want to reuse, and added some code in a reusable view itself(it's really not much more than a button that opens a PopoverController).
While this works fine in the iPad (the UIPopoverController presents itself, therefor needs no reference to a UIViewController), getting the same code to work means suddenly referencing your presentViewController from your UIViewController. Kinda inconsistent right?
Like mentioned before, it's not the best approach to have logic in your UIView. But it felt really useless to wrap the few lines of code needed in a separate controller.
Either way, here's a swift solution, which adds a new property to any UIView:
extension UIView {
var viewController: UIViewController? {
var responder: UIResponder? = self
while responder != nil {
if let responder = responder as? UIViewController {
return responder
}
responder = responder?.nextResponder()
}
return nil
}
}
While these answers are technically correct, including Ushox, I think the approved way is to implement a new protocol or re-use an existing one. A protocol insulates the observer from the observed, sort of like putting a mail slot in between them. In effect, that is what Gabriel does via the pushViewController method invocation; the view "knows" that it is proper protocol to politely ask your navigationController to push a view, since the viewController conforms to the navigationController protocol. While you can create your own protocol, just using Gabriel's example and re-using the UINavigationController protocol is just fine.
I don't think it's "bad" idea to find out who is the view controller for some cases. What could be a bad idea is to save the reference to this controller as it could change just as superviews change.
In my case I have a getter that traverses the responder chain.
//.h
#property (nonatomic, readonly) UIViewController * viewController;
//.m
- (UIViewController *)viewController
{
for (UIResponder * nextResponder = self.nextResponder;
nextResponder;
nextResponder = nextResponder.nextResponder)
{
if ([nextResponder isKindOfClass:[UIViewController class]])
return (UIViewController *)nextResponder;
}
// Not found
NSLog(#"%# doesn't seem to have a viewController". self);
return nil;
}
Swift 4
(more concise than the other answers)
fileprivate extension UIView {
var firstViewController: UIViewController? {
let firstViewController = sequence(first: self, next: { $0.next }).first(where: { $0 is UIViewController })
return firstViewController as? UIViewController
}
}
My use case for which I need to access the view first UIViewController: I have an object that wraps around AVPlayer / AVPlayerViewController and I want to provide a simple show(in view: UIView) method that will embed AVPlayerViewController into view. For that, I need to access view's UIViewController.
Two solutions as of Swift 5.2:
More on the functional side
No need for the return keyword now 🤓
Solution 1:
extension UIView {
var parentViewController: UIViewController? {
sequence(first: self) { $0.next }
.first(where: { $0 is UIViewController })
.flatMap { $0 as? UIViewController }
}
}
Solution 2:
extension UIView {
var parentViewController: UIViewController? {
sequence(first: self) { $0.next }
.compactMap{ $0 as? UIViewController }
.first
}
}
This solution requires iterating through each responder first, so may not be the most performant.
The simplest do while loop for finding the viewController.
-(UIViewController*)viewController
{
UIResponder *nextResponder = self;
do
{
nextResponder = [nextResponder nextResponder];
if ([nextResponder isKindOfClass:[UIViewController class]])
return (UIViewController*)nextResponder;
} while (nextResponder != nil);
return nil;
}
This doesn't answer the question directly, but rather makes an assumption about the intent of the question.
If you have a view and in that view you need to call a method on another object, like say the view controller, you can use the NSNotificationCenter instead.
First create your notification string in a header file
#define SLCopyStringNotification #"ShaoloCopyStringNotification"
In your view call postNotificationName:
- (IBAction) copyString:(id)sender
{
[[NSNotificationCenter defaultCenter] postNotificationName:SLCopyStringNotification object:nil];
}
Then in your view controller you add an observer. I do this in viewDidLoad
- (void)viewDidLoad
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(copyString:)
name:SLCopyStringNotification
object:nil];
}
Now (also in the same view controller) implement your method copyString: as depicted in the #selector above.
- (IBAction) copyString:(id)sender
{
CalculatorResult* result = (CalculatorResult*)[[PercentCalculator sharedInstance].arrayTableDS objectAtIndex:([self.viewTableResults indexPathForSelectedRow].row)];
UIPasteboard *gpBoard = [UIPasteboard generalPasteboard];
[gpBoard setString:result.stringResult];
}
I'm not saying this is the right way to do this, it just seems cleaner than running up the first responder chain. I used this code to implement a UIMenuController on a UITableView and pass the event back up to the UIViewController so I can do something with the data.
It's surely a bad idea and a wrong design, but I'm sure we can all enjoy a Swift solution of the best answer proposed by #Phil_M:
static func firstAvailableUIViewController(fromResponder responder: UIResponder) -> UIViewController? {
func traverseResponderChainForUIViewController(responder: UIResponder) -> UIViewController? {
if let nextResponder = responder.nextResponder() {
if let nextResp = nextResponder as? UIViewController {
return nextResp
} else {
return traverseResponderChainForUIViewController(nextResponder)
}
}
return nil
}
return traverseResponderChainForUIViewController(responder)
}
If your intention is to do simple things, as showing a modal dialog or tracking data, that doesn't justify the use of a protocol. I personally store this function in an utility object, you can use it from anything that implement the UIResponder protocol as:
if let viewController = MyUtilityClass.firstAvailableUIViewController(self) {}
All credit to #Phil_M
Maybe I'm late here. But in this situation I don't like category (pollution). I love this way:
#define UIViewParentController(__view) ({ \
UIResponder *__responder = __view; \
while ([__responder isKindOfClass:[UIView class]]) \
__responder = [__responder nextResponder]; \
(UIViewController *)__responder; \
})
Swiftier solution
extension UIView {
var parentViewController: UIViewController? {
for responder in sequence(first: self, next: { $0.next }) {
if let viewController = responder as? UIViewController {
return viewController
}
}
return nil
}
}
Swift 4 version
extension UIView {
var parentViewController: UIViewController? {
var parentResponder: UIResponder? = self
while parentResponder != nil {
parentResponder = parentResponder!.next
if let viewController = parentResponder as? UIViewController {
return viewController
}
}
return nil
}
Usage example
if let parent = self.view.parentViewController{
}
Updated version for swift 4 : Thanks for #Phil_M and #paul-slm
static func firstAvailableUIViewController(fromResponder responder: UIResponder) -> UIViewController? {
func traverseResponderChainForUIViewController(responder: UIResponder) -> UIViewController? {
if let nextResponder = responder.next {
if let nextResp = nextResponder as? UIViewController {
return nextResp
} else {
return traverseResponderChainForUIViewController(responder: nextResponder)
}
}
return nil
}
return traverseResponderChainForUIViewController(responder: responder)
}
To Phil's answer:
In line: id nextResponder = [self nextResponder]; if self(UIView) is not a subview of ViewController's view, if you know hierarchy of self(UIView) you can use also: id nextResponder = [[self superview] nextResponder];...
If you aren't going to upload this to the App Store, you can also use a private method of UIView.
#interface UIView(Private)
- (UIViewController *)_viewControllerForAncestor;
#end
// Later in the code
UIViewController *vc = [myView _viewControllerForAncestor];
var parentViewController: UIViewController? {
let s = sequence(first: self) { $0.next }
return s.compactMap { $0 as? UIViewController }.first
}
My solution would probably be considered kind of bogus but I had a similar situation as mayoneez (I wanted to switch views in response to a gesture in an EAGLView), and I got the EAGL's view controller this way:
EAGLViewController *vc = ((EAGLAppDelegate*)[[UIApplication sharedApplication] delegate]).viewController;
I think there is a case when the observed needs to inform the observer.
I see a similar problem where the UIView in a UIViewController is responding to a situation and it needs to first tell its parent view controller to hide the back button and then upon completion tell the parent view controller that it needs to pop itself off the stack.
I have been trying this with delegates with no success.
I don't understand why this should be a bad idea?
Another easy way is to have your own view class and add a property of the view controller in the view class. Usually the view controller creates the view and that is where the controller can set itself to the property. Basically it is instead of searching around (with a bit of hacking) for the controller, having the controller to set itself to the view - this is simple but makes sense because it is the controller that "controls" the view.
To get the controller of a given view, one can use UIFirstResponder chain.
customView.target(forAction: Selector("viewDidLoad"), withSender: nil)
If your rootViewController is UINavigationViewController, which was set up in AppDelegate class, then
+ (UIViewController *) getNearestViewController:(Class) c {
NSArray *arrVc = [[[[UIApplication sharedApplication] keyWindow] rootViewController] childViewControllers];
for (UIViewController *v in arrVc)
{
if ([v isKindOfClass:c])
{
return v;
}
}
return nil;}
Where c required view controllers class.
USAGE:
RequiredViewController* rvc = [Utilities getNearestViewController:[RequiredViewController class]];
There is no way.
What I do is pass the UIViewController pointer to the UIView (or an appropriate inheritance). I'm sorry I can't help with the IB approach to the problem because I don't believe in IB.
To answer the first commenter: sometimes you do need to know who called you because it determines what you can do. For example with a database you might have read access only or read/write ...