I have three view controllers in my app pushed to the navigation controller. When I'm on the third view controller I want to send a message to the first one. I think a delegate is the way to go here, but I'm not able to set it correctly.
In my third view controller's h-file I have this:
#protocol AddSudokusViewControllerDelegate
- (void)saveSudoku:(Sudoku *)sudoku;
#end
#interface [...]
id<AddSudokusViewControllerDelegate> delegate;
[...]
#property (nonatomic, retain) id<AddSudokusViewControllerDelegate> delegate;
Then I synthesize it in the .m file.
In my first view controller I have this (.h):
#interface SudokusViewController : UITableViewController <AddSudokusViewControllerDelegate>{
[...]
}
- (void)saveSudoku:(Sudoku *)sudoku;
So far so good I think. Now I want to set the delegate of the third view controller to first when I create it in the second controller. I thought I could do it like this, but it doesn't work.
sudokuDetailViewController = [[SudokuDetailViewController alloc] init];
[sudokuDetailViewController setDelegate:[[self navigationController] parentViewController]];
[[self navigationController] pushViewController:sudokuDetailViewController animated:YES];
Am I doing this the right way or is there another approach when you have three controllers like this?
Best Regards
Linus
Try this,
sudokuDetailViewController.delegate = [self.navigationController.viewControllers objectAtIndex:0];
Related
I'm using Xcode to write an app in objective c. I am trying to pass data from a container view controller to the parent view controller using delegation. I have successfully passed the data to the parent view controller, but all of the documentation sets what I have sent to the .h header file in the .m implementation file using viewDidLoad or viewDidAppear. I was wondering, since the view is already present, if there is a way to detect that data has been changed in a view and automatically run a method or code to update the view with the new information. Something along the idea of didReceiveNewData or didEditExistingValues (of course those arent real methods). Thank you for your help!
Edit: What I have done so far:
I want to pass the data from MainFeedTableViewController to MainFeedViewController (The first is in a container inside of the second). I want to set the title of the custom navigation bar in MainFeedViewController to something described in the MainFeedTableViewController.
In the MainFeedTableViewController.m (the view sending data) I have:
#import "MainFeedTableViewController.h"
#import "FeedViewController.h"
#interface MainFeedTableViewController ()
#end
#implementation MainFeedTableViewController
- (IBAction)swipeLeftDetected:(UIGestureRecognizer *)sender {
UIStoryboard *mc = self.storyboard;
FeedViewController *fv = [mc instantiateViewControllerWithIdentifier:#"FeedViewController"];
fv.navigationBarTitleToSet = #"HOPING TO SET TITLE TO THIS";
[self performSegueWithIdentifier:#"MainToLocalFeed" sender:self];
}
and some other unrelated stuff..
In the MainFeedTableViewController.h I have:
#import <UIKit/UIKit.h>
#interface MainFeedTableViewController : UITableViewController
#end
In the MainFeedViewController.m (the one receiving the data) I have:
#import "FeedViewController.h"
#interface FeedViewController () <UINavigationBarDelegate>
#property (weak, nonatomic) IBOutlet UINavigationBar *navigationBar;
#end
#implementation FeedViewController
- (void)viewDidLoad {
[super viewDidLoad];
}
- (void)setNavigationBarTitle:(NSString *)navigationBarTitle{
self.navigationItem.title = navigationBarTitle;
}
And in the MainFeedViewController.h I have:
#import <UIKit/UIKit.h>
#interface FeedViewController : UIViewController
#property NSString *navigationBarTitleToSet;
#end
I want to run the setNavigationBarTitle method with either data from the .h (navigationBarTitleToSet) or just from the sending view controller, if possible to run a method with delegation. Thanks a ton and I hope this is possible :)
It turns out I needed to add a second navigation bar to account for the container view, allowing me to navigate around the current stack with the parentViewController method and then navigationItem.title. For anyone who happens to find this with a container, make sure you add one immediately after the embed segue. I'm still not sure if you can use methods through delegation, but I can't ponder any situations where it would be necessary anymore, due to viewDidLoad. Thanks to #Tander for the help!
I have a table view in my previous view which is get data from an array in my app. I have a view to update data which is push on cell select. Once data is updated in the view i call
[self.navigationController popViewControllerAnimated:YES];
to go back to previous view. But the label get stacked with old and new data I don't know why... If I go one view back and come back again to the tableview everything is fine only new data is shown..
So I guess I have to rebuild view to avoid the problem. Is this possible ?
Your question initially asked about rebuilding a controller, so here's the answer to that:
I'm assuming that your have a navigation stack like this:
An instance of FirstController
An instance of SecondController
An instance of ThirdController
A thing happens in your third controller, and you now want the stack to look like this:
An instance of FirstController
A new instance of SecondController
The first thing to do is to define a delegate protocol for ThirdController, in your header file like this:
#protocol ThirdControllerDelegate;
#class ThirdController : UIViewController
#property (nonatomic, weak) id<ThirdControllerDelegate> delegate;
... your existing stuff ...
#end
#protocol ThirdControllerDelegate <NSObject>
- (void)thirdControllerDidDoTheThing:(ThirdController *)thirdController;
#end
Instead of having the ThirdController pop itself, it should tell its delegate that the thing happened, like so:
[self.delegate thirdControllerDidDoTheThing:self];
You'll also want to define a delegate protocol for SecondController, in the same way, and you'll want to specify that SecondController can act as a delegate for a ThirdController:
#import "ThirdController.h"
#protocol SecondControllerDelegate;
#class SecondController : UIViewController <ThirdControllerDelegate>
#property (nonatomic, weak) id<SecondControllerDelegate> delegate;
... your existing stuff ...
#end
#protocol SecondControllerDelegate <NSObject>
- (void)secondControllerDidDoTheThing:(SecondController *)secondController;
#end
Notice the extra bit in there where we put <ThirdControllerDelegate> after the #class line.
Now we find the part of the SecondController that shows the ThirdController, and have it set the controller's delegate first:
- (void)showThirdControllerAnimated:(BOOL)animated
{
ThirdController *thirdController = [[ThirdController alloc] init];
thirdController.delegate = self;
[self.navigationController pushViewController:thirdController animated:animated];
}
When the SecondController gets the message from the ThirdController, it should pass it on to its delegate, like this:
- (void)thirdControllerDidDoTheThing:(ThirdController *)thirdController
{
[self.delegate secondControllerDidDoTheThing:self];
}
Finally we modify FirstController so that it can act as the delegate to the SecondController:
#import "SecondController."
#class FirstController : UIViewController <SecondControllerDelegate>
When we show the SecondController, we make the FirstController its delegate:
- (void)showSecondControllerAnimated:(BOOL)animated
{
SecondController *secondController = [[SecondController alloc] init];
secondController.delegate = self;
[self.navigationController pushViewController:secondController animated:animated];
}
Finally we implement the SecondController's delegate method to pop to the first controller, then show a new secondController.
- (void)secondControllerDidDoTheThing:(SecondController *)secondController
{
[self.navigationController popToViewController:self animated:NO];
[self showSecondControllerAnimated:NO];
}
Done.
You've since altered your question; in the case you now describe you can follow the steps above to make the SecondController the delegate of the ThirdController, but then inside thirdControllerDidDoTheThing you just reload the data of your SecondController's view; if it's a UITableView or UICollectionView you'd do that with the reloadData method.
you should refresh your table view every time it is going to be shown; otherwise, the old data would be cached.
In the controller that controls the table view:
- (void)viewWillAppear {
[tableView reloadData];
}
I would like to create a UITabbar like below but i don't know what is the logic to do that.
Here is the large answer:
First of all, you will need to create a UIView subclass to get a view that looks like the bar that you want. It can be composed by a background UIImageView and three buttons.
Then, the best thing would be to create a subclass of the UITabBarController and in its viewDidLoad or at any point where the flow will go through just once, you instantiate one view of type specified at first point. You should place the frame of this view in order to hide the original tabbar of the controller.
This would be the custom bar header file:
#interface CustomBar : UIView
{
}
#property (nonatomic, retain) UIImageView *backgroundView;
#property (nonatomic, retain) NSArray *buttons;
#end
You can easily complete the implementation. You can try to look for how to instantiate it with a nib file to make it easier to design it. In order to test, you can first just set the background color to green or something visible.
Then, this would be the subclass of the UITabBarController class:
#interface CustomTabBarController : UITabBarController
#property (nonatomic, retain) CustomBar *customBar;
#end
#implementation CustomTabBarController
- (void)viewDidLoad
{
[super viewDidLoad];
self.customBar = [[[CustomBar alloc] initWithFrame:[self.tabBar frame]] autorelease];
[self.view addSubview:self.customBar];
}
#end
Please, remember to implement the dealloc if you are not using ARC.
The thing I am not sorting out here is how to create the communication between the buttons from the custombar and the tabbarcontroller. This should be solved by delegates. If you need help with that, I will complete that too.
Good luck!
The first UITableView is presented inside a Popover that is called from the RootViewController of the application.
I need to navigate to another UITableView inside the same popover. This is easy to do if you just instance an object of the second UITableView and push it from the first one.
In the next paragraph I write as taking for granted some facts, please correct me if I'm wrong.
The problem here is that this process should be done inside the appDelegate. This is because I'm implementing Dropbox API and I need the pushViewController to be done immediately after the login process is done, which means the navigation through UITableViews has to be done inside of the application:handleOpenURL. I asume that application:handleOpenURL has to be called right there and that's why I also asume the pushViewController has to be done there in order to have the navigation done after the Dropbox API validation window is presented, without having to make the user do anything else.
This is how my code looks like:
AppDelegate.h
#interface AppDelegate : NSObject <UIApplicationDelegate>{
UINavigationController *navigationController;
NSString *relinkUserId;
UIWindow *window;
TableViewControllerForStorageList *rootViewController;
ViewController *viewController;
}
#property (nonatomic, strong) IBOutlet UIWindow *window;
#property (nonatomic, strong) IBOutlet UINavigationController *navigationController;
#property (nonatomic, strong) IBOutlet TableViewControllerForStorageList *rootViewController;
#property (nonatomic, strong) IBOutlet ViewController *viewController;
AppDelegate.m
- (BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url {
if ([[DBSession sharedSession] handleOpenURL:url]) {
if ([[DBSession sharedSession] isLinked]) {
[(TableViewControllerForStorageList *)self.window.rootViewController PushView];
}
return YES;
}
return NO;
}
TableViewControllerForStorageList.h
-(void)PushView;
TableViewControllerForStorageLost.m
-(void)PushView
{
TableViewControllerIpadStorage *tableViewControllerIpadStorage = [[TableViewControllerIpadStorage alloc]initWithNibName:#"TableViewControllerIpadStorage" bundle:Nil];
[self.navigationController pushViewController:tableViewControllerIpadStorage animated:YES];
}
Off course I got sure that Application:HandleOpenURL is running, but when calling PushView from there the error is [ViewController PushView]: unrecognized selector sent to instance
So, how can make the navigation be done from there? Which basics about objective c am I missing?
It is not clear from your question how your app is structured, so this answer may not be the best solution for your problem but hopefully it gives you some idea of how your view controller hierarchy is likely built up from your app delegate.
Lets say your first view controller class is named FirstViewController. Either your app delegate has a direct reference to an instance of this view controller, or it can access it through a parent view controller (perhaps via window.rootViewController).
Now lets say you have a method in FirstViewController named pushNextViewController that performs the task of pushing the second table view controller.
You can call that method from within the application:handleOpenURL: method of your app delegate.
This might look something like:
[self.window.rootViewController.firstViewController pushNextViewController];
There are other ways you could get a reference to your instance of FirstViewController and it would be cleaner if your rootViewController was a custom subclass so your could create a pushNextViewController method there and from that method tell your FirstViewController instance to pushNextViewController:
[self.window.rootViewController pushNextViewController];
Note that in both examples above, you will need to cast the rootViewController to whatever class it is actually an instance of or the compiler will warn you that it does not have the property firstViewController (example 1) or the method pushNextViewController (example 2).
EDIT: If your rootViewController is a UINavigationController, then your code might look more like:
UINavigationController* navController = (UINavigationController*)window.rootViewController;
FirstViewController* vc = navController.viewControllers[0];
[vc pushNextViewController];
EDIT 2: OK, It looks like the confusion here is that the window object has a rootViewController property (which appears to be pointing to your navigationController) and then you also have a rootViewController instance variable in your app delegate. These are two different objects, making your naming convention a bit confusing, but if I am right then the following should work:
- (BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url {
if ([[DBSession sharedSession] handleOpenURL:url]) {
if ([[DBSession sharedSession] isLinked]) {
[rootViewController PushView];
}
return YES;
}
return NO;
}
You should consider changing the name of your app delegate's reference to your TableViewControllerForStorageList to something other than rootViewController to alleviate some confusion.
I have achieved this but I am asking more if I did this right. I have been immersed in the apple documentation and iOS programming books. Since then I have fully reworked my app for reusability and all that good stuff.
Now I have a main UIViewController named RootController that handles a UINavigationController and a custom MenuController. I decided that UIViewController containment was the best approach for my RootController.
RootController ---> UINavigationController
---> MenuController
Now a problem occurred where I needed some of the sub UIViewControllers in the UINavigationController to communicate with the main RootController.
RootController ---> UINavigationController --> UIViewController
^_____________________________________________|
What I decided to do was extend UIViewController with a category.
UIViewController+RootController.h
#interface UIViewController (RootController)
#property (nonatomic, readonly) RootController *rootController;
#end
UIViewController+RootController.m
#implementation UIViewController (RootController)
- (RootController *)rootController {
static RootController *rootControler;
if(rootControler == nil) {
UIViewController *vc = self;
while((vc = vc.parentViewController)) {
if([vc isMemberOfClass:[RootController class]]){
rootControler = (RootController *)vc;
break;
}
}
}
return rootControler;
}
#end
When [self rootController] is called by any UIViewController it will loop through the parent view controllers until it find one that matches RootController, it will then return the match. I also made the property static so it was only looked up once.
So my question is was this the right approach I made? I was trying to make something similar to UIViewController's navigationController method.
I need access to the main root controller so I can handle the MenuController from any view within my app.
Your solution seems correct but not so clean imho.
In similar situations I usually prefer to obtain a reference in "inverse" method, using the AppDelegate.
For Example:
#import "AppDelegate.h" // at the top of your file
UIViewController *vc = [[(AppDelegate *)[[UIApplication sharedApplication] delegate] window] rootViewController]:
vc is a reference to your root view controller.
Take care because the root view controller of the window can change (if you change it :-). So, in this case, you should change your aproach (for example adding a #property to your AppDelegate and make your RootController setting this property on load)