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Passing Data between View Controllers
I have 2 modal views. The first modal view is used to edit quantity and price; the second modal view is used when we click the price textfield of first modal view in order to give give reason why we change the price and we can put new price in price textfield of modal view. I want the price in first modal view change when I set the price in second modal view. How to catch the value of second modal view to put in first modal view ?
Use NSNotification center
You have to addobserver event in First Modalview
-(void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(reload:) name:#"refresh" object:nil];
}
- (void)reload:(NSNotification *)notification {
textfield.text= [[notification userInfo] valueForKey:#"price"] ;
}
In second modalview you have to post notification after you complete edit
(pass your textfield value)
NSDictionary *userInfo = [NSDictionary dictionaryWithObject:#"333" forKey:#"price"];
[[NSNotificationCenter defaultCenter] postNotificationName:#"refresh" object:nil userInfo:userInfo]
;
Finally remove observer
-
(void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
[[NSNotificationCenter defaultCenter] removeObserver:self name:#"refresh" object:nil];
}
You can used Singleton just to save some data on that class
The following simple steps will make you able to do this.
In the first Modal ViewController, you can declare a function like
- (void) setUpdatedValueWithValue: (NSString *) newValue
{
self.objTextField.text = newValue;
}
Declare this function on the header file too, so that we can access it from the other class.
In the second Modal ViewController
SecondViewController.h
#interface SecondViewController : UIViewController
{
id objFirstViewController;
}
#property (nonatomic, retain) id objFirstViewController;
#end
SecondViewController.m
#implementation SecondViewController
#synthesize objFirstViewController;
#end
Before you present the SecondViewController pass the object of FirstViewController to SecondViewController like,
- (void) presentSecondViewController
{
SecondViewController *objSecondViewController = [[SecondViewController alloc] init];
objSecondViewController.objFirstViewController = self;
[self presentModalViewController: objSecondViewController animated: YES];
[objSecondViewController release];
objSecondViewController = nil;
}
Then, in the function you are calling to dismiss the SecondViewController after the value edit you can do like,
- (void) finishEdit
{
if([objFirstViewController respondsToSelector: #selector(setUpdatedValueWithValue:)])
{
[objFirstViewController performSelector: #selector(setUpdatedValueWithValue:) withObject: editedTextView.text];
}
[self dismissModalViewControllerAnimated: YES];
}
Hope this helps.
set you object with your keyword
[[NSUserDefaults standardUserDefaults]setObject:#"value of second modal view" forKey:#"keyName"];
than get that object in first modal view
NSString *name = [[NSUserDefaults standardUserDefaults]objectForKey:#"keyName"];
Related
I have a modalViewController that comes up over the top of a viewController with a tableView. When the user clicks a button on the modalViewController I want to reload the tableView within the viewController with this:
[tableView1 reloadData];
I do not want to put the reload in the viewDidAppear or viewWillAppear methods as they get called when i do not need the tableView to reload (i.e. when the user clicks the back button to return to the tableView).
Is there a way to do this?
Try
1) write one method which reloads the table data.
2) Call it on the back button clicked.
This is the classic delegate pattern problem, in your modal view controller you need a delegate reference to the current view controller presenting it
//Modal
#protocol ModalVCDelegate
- (void)tappedBackButton;
#end
#class ModalVC: UIViewController
#property id<ModalVCDelegate> delegate;
#end
#implementation
- (void)backButtonTapped:(id)sender
{
if (self.delegate)
[self.delegate tappedBackButton];
}
#end
Now, in your presenting VC, just process this delegate message
//Parent VC
- (void)showModal
{
ModalVC *vc = [ModalVC new];
vc.delegate = self;
//push
}
- (void)tappedBackButton
{
[self.tableView reloadData];
//close modal
}
You can use delegate . If find it more harder then alternative is to use NSNotificationCenter. You can see accepted answer for Refreshing TableView. This is really very short, easy and understandable way.
using Notification like bellow Method:-
Create NSNotificationCenter at yourViewController's ViewdidLoad Mehod
- (void)viewDidLoad
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(ReloadDataFunction:)
name:#"refresh"
object:nil];
[super viewDidLoad];
}
-(void)ReloadDataFunction:(NSNotification *)notification {
[yourTableView reloadData];
}
Now you can Call this Notification from your modelViewController BackButton or else you want from calling this Refresh notification like putting this line of code:-
[[NSNotificationCenter defaultCenter] postNotificationName:#"refresh" object:self];
NOTE: postNotificationName:#"refresh" this is a key of particular Notification
Try to use this one
Make a Button and click on this button and than you can reload your data.
This button make custom and use it on background.
- (IBAction)reloadData:(id)sender
{
[tblView reloadData];
}
You can use NSNotification to refresh table on ViewController.
Inside viewController :
-(void)dealloc{
[[NSNotificationCenter defaultCenter] removeObserver:self];
[super dealloc];
}
Write code in viewDidLoad:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(reloadMainTable:)
name:#"ReloadTable"
object:nil];
- (void) reloadMainTable:(NSNotification *) notification
{
[tableView reload];
}
Inside ModelViewController:
[[NSNotificationCenter defaultCenter]
postNotificationName:#"ReloadTable"
object:nil];
Here you can also send custom object instead of nil parameter. But be care full about removal of NSNotification observer.
I came across an interesting problem, i have main ViewController let's call him MainVC with navigationController and i am doing performSegueWithIdentifier from him to Mine second ViewController let's call him SecVC. so when i am trying to do the popViewControllerAnimated i want to pass some data from the SecVC to the MainVc.. i know i can do it with appDelegate Param or with singletons class but my question is : can i do it with more Elegant solution? like i use prepareForSegue and use local parmeters..
Thank you...
The best way to do it is by using a delegate.
//SecVCDelegate.h
#import <Foundation/Foundation.h>
#protocol SecVSDelegate <NSObject>
#optional
- (void)secVCDidDismisWithData:(NSObject*)data;
#end
//SecVC.h
#import <UIKit/UIKit.h>
#import "SecVSDelegate.h"
#interface SecVC : UIViewController
/** Returns the delegate */
#property (nonatomic, assign) id<SecVSDelegate> delegate;
#end
//SecVC.M
...
- (void) dealloc
{
...
delegate = nil
...
}
When ever you popViewControllerAnimated, right after it (or before it) you do this
if(_delegate && [_delegate respondsToSelector:#selector(secVCDidDismisWithData:)])
{
[_delegate secVCDidDismisWithData:myDataObject];
}
And in the MainVC you must be certain that you implement the delegate function
//MainVC.m
- (void)secVCDidDismisWithData
{
//do whatever you want with the data
}
To avoid any warnings you must tell that the MainVC class implements the delegate like this:
//MainVC.h
#import "SecVCDelegate.h"
...
#interface MainVC : UIViewController <SecVCDelegate>
...
secVCInstance.delegate = self;
[self.navigationController pushViewController:secVCInstance];
...
While I agree that the best option is to use Delegate,
but still if any one is looking for something different, he can use NSNotificationCenter as an alternative.
In viewDidLoad of MainVC:
- (void)viewDidLoad
{
[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(recvData:)
name:#"SecVCPopped"
object:nil];
}
And add method recvData in MainVC.m
- (void) recvData:(NSNotification *) notification
{
NSDictionary* userInfo = notification.userInfo;
int messageTotal = [[userInfo objectForKey:#"total"] intValue];
NSLog (#"Successfully received data from notification! %i", messageTotal);
}
Now in SecVC, before popping, add this line
NSMutableDictionary* userInfo = [NSMutableDictionary dictionary];
[userInfo setObject:[NSNumber numberWithInt:messageTotal] forKey:#"total"];
NSNotificationCenter* nc = [NSNotificationCenter defaultCenter];
[nc postNotificationName:#"SecVCPopped" object:self userInfo:userInfo];
I would do it in one of the following ways, but I'm not sure if it's elegant enough...
In SecVC, add an #property MainVC *mainVC; Use [self.mainVC setSomeValue:...]; before calling [self.navigationController popViewControllerAnimated:...];
Use [self.navigationController viewControllers]; to find out the MainVC *mainVC, and call [mainVC setSomeValue:...]; before the line of code that pop the ViewController.
Is this what you want?
I simply set up a protocol in the view being dismissed (example in Swift):
protocol ExampleTableViewControllerDismissDelegate {
func didDismiss(withData: Any)
}
var delegate: SearchableTableViewControllerDismissDelegate?
You can then call this when you dismiss/pop your view like this
self.navigationController?.popViewController(animated: true)
delegate?.didDismiss(withData: Any)
Then in the view being dismissed to (the parent in the hierarchy), we can conform to the delegate and essentially get a callback with the data after the view has been dismissed.
//MARK: ExampleTableViewControllerDismissDelegate
func didDismiss(withData: Any) {
//do some funky stuff
}
And don't forget to subscribe to the delegate in the parent view by using
viewController.delegate = self
There is another way to pass data between views including popViewControllerAnimated and it's with a global var instance, so If you modify that Var in your detail view and after do the popViewControllerAnimated, you can call the new data in the viewWillAppear method.
The first step is declare the Global var in main.h
NSMutableArray * layerList;
And now you have to call it in detail view.
SecondView.m
extern NSString *layerList;
SecondView.h
-(void)back{
layerList = #"Value to send";
[self.navigationController popViewControllerAnimated:YES];
}
Now you can use the information in the Master View after detect the pop action.
FirstView.m
extern NSString *layerList;
FirstView.h
-(void)viewWillAppear:(BOOL)animated{
NSLog(#"This is what I received: %#",layerList);
}
I do have two ViewController class, one firstviewController other secondViewController in first viewcontroller i call this [self dimissModalViewControllerAnimation:NO];
to dimiss the view! now i need to dimiss the same view from another secondViewController class.
So do i need to call super in that!
[super dismissModalViewControllerAnimated:NO];
Or Do i need to create any protocol for dismissing the view! from another secondViewController class.
Can any guide me with this issue.
you can register a notification in firstViewController's viewDidLoad
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(handleNotification:) name:#"MyNotification" object:nil];
Add the event handler in firstViewController
- (void)handleNotification:(NSNotification*)note {
[self dismissModalViewControllerAnimated:NO];
}
Then you can trigger the event in secondViewController
[[NSNotificationCenter defaultCenter] postNotificationName:#"MyNotification" object:nil ];
You should only be using super when you're overloading a method definition, e.g.:
- (void)viewDidLoad
{
[super viewDidLoad];
self.title = #"Login / Signup";
}
Typically, if you're trying to tell one view to do something from another view, delegates are your friend. You could create a weak delegate variable to hold a reference to the view controller to be dismissed, and call [delegate dismissModalViewControllerAnimated:NO];
I am trying to update a UILabel in a parent View after someone makes a change in a modal view. So, after they click "save" ... the newly entered value would change what text is displayed on the parent view controller.
But, I can't seem to get that UILabel to refresh the newly entered value.
Any ideas on what I can try? I've tried a few things, but being the view is already loaded, nothing is getting "refreshed".
Thanks!
There are many ways to do this. One way is to use NSNotificationCenter to be able to do calls between different classes. So in the parent view you will have a function responsible for the update (lets call it updateLabel) and you will do the following:
- (void) updateLabel
{
yourLabel.text = #"what you need";
}
- (void)viewDidLoad
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(updateLabel) name:#"DoUpdateLabel" object:nil];
}
Now in other view simply post a notification in the save button:
[[NSNotificationCenter defaultCenter] postNotificationName:#"DoUpdateLabel" object:nil userInfo:nil];
EDIT:
I have to mention 2 things here:
In this scenario it is always preferable to have Shared Data Modal where you save your data in so you can access this data in any view in your program. In other words it is a good practice to separate the data from classes.
Remember to resomve the NSNotificationCenter that you used in the main view by adding [[NSNotificationCenter defaultCenter] removeObserver:self];
To elaborate on my comment. This is how I would implement a delegation method to update the label.
In the header of the parent view controller:
#import "ModalViewController.h"
#interface ViewController : UIViewController <ModalViewControllerDelegate>
/* This presents the modal view controller */
- (IBAction)buttonModalPressed:(id)sender;
#end
And in the implementation:
/* Modal view controller did save */
- (void)modalViewControllerDidSave:(ModalViewController *)viewController withText:(NSString *)text
{
NSLog(#"Update label: %#", text);
}
/* Prepare for segue */
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"modalSegue"])
{
ModalViewController *mvc = (ModalViewController *) segue.destinationViewController;
mvc.delegate = self;
}
}
/* Present modal view */
- (IBAction)buttonModalPressed:(id)sender
{
[self performSegueWithIdentifier:#"modalSegue" sender:self];
}
Here you see the delegation method in the top.
The header of the modal view controller would contain the delegation protocol like this:
#protocol ModalViewControllerDelegate;
#interface ModalViewController : UIViewController
#property (nonatomic, weak) id <ModalViewControllerDelegate> delegate;
- (IBAction)buttonSavePressed:(id)sender;
#end
#protocol ModalViewControllerDelegate <NSObject>
- (void)modalViewControllerDidSave:(ModalViewController *)viewController withText:(NSString *)text;
#end
The implementation of the modal view controller would contain a method similar to this one:
/* Save button was pressed */
- (IBAction)buttonSavePressed:(id)sender
{
if ([self.delegate respondsToSelector:#selector(modalViewControllerDidSave:withText:)])
[self.delegate modalViewControllerDidSave:self withText:#"Some text"];
[self dismissModalViewControllerAnimated:YES];
}
When the save button is pressed, the delegate is notified and the text in your text view is sent through the delegation method.
in SWIFT:
ParentViewController :
func updateLabel() {
yourLabel.text! = "what you need"
}
override func viewDidLoad() {
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(self.updateLabel), name: "DoUpdateLabel", object: nil)
}
In OtherView:
#IBAction func closePopUp(sender: AnyObject) {
NSNotificationCenter.defaultCenter().postNotificationName("DoUpdateLabel", object: nil, userInfo: nil)
}
I have a TabBarController with 2 tabs, in one is a MapView and in the other one a simple TableView in a NavigationController. Both display Data from the same source. If any Data in the table is tapped, I add a DetailViewController to the NavigationController and show more details. Now on the MapView I also want to open this DetailViewController when the Data is tapped in the map. What's the best way to do this? I tried some with Notification but this doesn't work well because the TableViewController is finished loading (and registered as an observer) after the Notification is sent.
Here's my code:
MapViewController:
- (IBAction)goToNearestEvent:(id)sender {
if (currentNearestEvent) {
[[self tabBarController] setSelectedIndex:1];
NSDictionary *noteInfo = [[NSDictionary alloc] initWithObjectsAndKeys:currentNearestEvent, #"event", nil];
NSNotification *note = [NSNotification notificationWithName:#"loadDetailViewForEvent" object:self userInfo:noteInfo];
[[NSNotificationCenter defaultCenter] postNotification:note];
[noteInfo release];
}
}
TableViewController:
- (void)viewDidLoad {
[super viewDidLoad];
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc addObserver:self
selector:#selector(loadDetailViewForEvent:)
name:#"loadDetailViewForEvent"
object:nil];
}
- (void)loadDetailViewForEvent:(NSNotification *)note {
Event *e = [[note userInfo] objectForKey:#"event"];
[self loadEventDetailViewWithEvent:e];
}
So I'm very new to iOS / Cocoa programming. Maybe my approach is the wrong choice. So I hope anybody could tell me how to solve such things the right way.
I forgot to declare my structure clearly:
- UITabBarController
- MapView (1)
- NavigationControllerContainer
- NavigationControllerView (2)
- TableView
I want to push a new View from the MapView (1) to the NavigationControllerView (2).
If you're going to use notifications, the fix is to force the second tab to be "created" before it's displayed.
Something like:
UIViewController *otherController = [[[self tabBarController] viewControllers] objectAtIndex:1];
otherController.view; // this is magic;
// it causes Apple to load the view,
// run viewDidLoad etc,
// for the other controller
[[self tabBarController] setSelectedIndex:1];
I don't have access to my code, but I did something similar to:
[[self.tabBarController.viewControllers objectAtIndex:1] pushViewController:detailView animated:YES];
Give this a try and let me know.
I think the observer/notification pattern is the right one. However, you normally want "controllers" to observe "model" objects.
I would create a Model object that contains the selected Event.
When each viewController is loaded, it looks at the "Model" object and directs itself to the selected event.
When any of the viewControllers changes the selected event, it does so in the Model, and then the notification propagates to the other(s) controllers.