I have FirstViewController and SecondTableViewController. In SecondTableViewController.m, I create a cell in the cellForRow... method where the cell.textLabel.text is a string from an NSInteger property ("count") of the SecondTableViewController.
I would like a button in FirstViewController to increment the value of count.
I've tried making a property of FirstViewController and then using that:
#property SecondTableViewController *viewController;
and
- (IBAction)buttonTouched:(id)sender {
self.viewController.count++;
[self.viewController.tableView reloadData];
}
But this way isn't working. count is still its original value of zero. I've also reloaded the table in viewWillAppear and still nothing. How can I do this?
Count being used as a property may be where you are going wrong because count is a method that returns the number of objects in an array that is found in foundation framework. Also keep in mind that if you are storing a integer into a string object try storing it in this format.
cell.textlabel.text = [NSString stringWithFormat: #"%i", count];
Hope this helps
Try following
firstViewController.h
#interface DMFirstViewController : UIViewController
#property (nonatomic, strong) DMSecondViewController * secondController;
- (IBAction)buttonPressed:(id)sender;
#end
firstViewController.m
- (IBAction)buttonPressed:(id)sender
{
++self.secondController.count;
[self.navigationController pushViewController:self.secondController animated:YES];
}
secondViewController.h
#property (nonatomic) int count;
secondViewController.m
-(void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
NSLog(#"%d", self.count);
}
EDIT
Check out those two images and implement the similar logic and get the solution.
----- END OF NEW EDIT -----
OLD
I think you haven't assigned and allocated memory for SecondTableViewController reference i.e, self.viewController of FirstViewController in its viewDidLoad method i.e,
-(void) viewDidLoad //In FirstViewController
{
self.viewController = [[SecondTableViewController alloc] init];
}
and pushed the same reference on to the stack of navigationController after performing button taps to increase the count of count variable of SecondTableViewController.
If you are not clear, comment.
Related
I have an NSMutableArray declared as property in .h and initialized in viewDidLoad in my SPOCVC .m (UIViewController)...
#property (strong, nonatomic) NSMutableArray* SPOCTrackList;
in viewDidLoad
if ([self SPOCTrackList] == nil) {
self.SPOCTrackList = [[NSMutableArray alloc]init];
NSLog(#"SPOTTrackList INITIALIZED");
}
In a separate VC, I'm trying to pass/addObject to SPOCTracklist...
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
SCTrack* selectedTrack = self.trackList[indexPath.row];
[[[SPOCVC sharedInstance]SPOCTrackList]addObject:selectedTrack];
NSLog(#"%lu", (unsigned long)[[[SPOCVC sharedInstance]SPOCTrackList]count]);
So my NSMutableArray is initialized and I can add dummy objects, but why can't I pass it from another VC using singleton or anything, such as...
SPOCVC* spocVC = self.tabBarController.viewControllers[2];
[spocVC.SPOCTrackList addObject:selectedTrack];
Thanks for pointing me in the right direction.
View controllers are only intended to be around while they are on screen. They are not a place to store data. Generally when one view controller talks directly to another view controller that it didn't create, you're doing something wrong.
Move SPOCTrackList to your model and have both view controllers talk to it rather than to each other.
There should never be a "sharedInstance" on a view controller. That's a sure sign that you're abusing the view controller as the model.
What's probably happening in your particular case is that viewDidLoad is running on a completely different SPOCVC than your sharedInstance.
why not use appdelegate to handle this
appdelegate.h
//add property to hold the reference
#property (nonatomic, copy) NSMutableArray *referenceArray;
//share the app delegate
+(AppDelegate *)sharedAppDelegate;
#end
in appdelegate.m
//synthesize the property
#synthesize referenceArray;
//return the actual delegate
+(AppDelegate *)sharedAppDelegate {return (AppDelegate *)[UIApplication sharedApplication].delegate;}
in viewdidload method
//add the delegate
import "appdelegate.h"
//init the array
self.SPOCTrackList = [[NSMutableArray alloc]init];
//Add reference
[AppDelegate sharedAppDelegate].referenceArray = self.SPOCTrackList;
and add anywhere like this
import "appdelegate.h"
[[AppDelegate sharedAppDelegate].referenceArray addobject:object];
hi i am working on an app and all was going good till now.... i am stuck at this point..
here is my storyboard snapshot..
in the DemoTableViewController when i clock on "filters" button .. Brands TableViewController is opened modally .
after user select multiple rows in Brands TableViewController ,, he then clicks on done button and view controller is dismissed by this code:
-(IBAction)DonePressed:(id)sender {
[self dismissViewControllerAnimated:YES completion:nil];
}
I am storing the user selections in NSMutableSet and it is to be Used in DemoTableViewController so that i can reload the table rows according to the selection but i dont know how to send NSMutableSet to DemoTableViewController and then reload the table according to selection..
what is the right way to dismiss modal view and reload the parent DemoTableViewController
i know i am not doing it correctly but can anyone help me in doing it...
here is some code ---
DemoTVC.h
#import <UIKit/UIKit.h>
#import "MyModelClass.h"
#import "brandsTableViewController.h"
#interface demoTableViewController : UITableViewController<UITableViewDataSource,UITableViewDelegate,MyModelProtocol,FilterProtocol>
#property (strong, nonatomic) IBOutlet UITableView *demoTable;
- (IBAction)FilterPressed:(id)sender;
#end
DemoTVC.m--
the method which performs segue--
- (IBAction)FilterPressed:(id)sender {
[self performSegueWithIdentifier:#"FilterPressed" sender:self];
}
the delegate method which is called to get the values from BrandsTVC--
-(void)GetTheSet:(NSMutableSet *)MySet{
[self dismissViewControllerAnimated:YES completion:nil];
}
viewdidLoad--
- (void)viewDidLoad
{
[super viewDidLoad];
productArray = [[NSMutableArray alloc] init];
homeModel = [[MyModelClass alloc] init];
// Set this view controller object as the delegate for the home model object
homeModel.delegate = self;
// Call the download items method of the home model object
[homeModel downloadItemswithurl:#"url is written here"];
}
BrandsTVC.h---
#import <UIKit/UIKit.h>
#import "MyModelClass.h"
#protocol FilterProtocol <NSObject>
-(void)GetTheSet:(NSMutableSet *) MySet;
#end
#interface brandsTableViewController : UITableViewController<UITableViewDataSource,UITableViewDelegate,MyModelProtocol>
#property (strong, nonatomic) IBOutlet UITableView *RetailerList;
#property (strong,nonatomic) NSMutableSet *selectStates;
#property (nonatomic, weak) id<FilterProtocol> delegate;
- (IBAction) DonePressed:(id)sender;
#end
BrandsTVC.m---
#interface brandsTableViewController ()
{
MyModelClass *myModelClass;
NSMutableArray *BrandsArray;
brandsTableViewController *Delegate;
}
#end
viewDidLoad----
- (void)viewDidLoad
{
[super viewDidLoad];
BrandsArray = [[NSMutableArray alloc] init];
self.selectStates=[NSMutableSet new];
myModelClass = [[MyModelClass alloc] init];
// Set this view controller object as the delegate for the home model object
myModelClass.delegate = self;
// Call the download items method of the home model object
[myModelClass downloadItemswithurl:#"url to get json"];
self.tableView.allowsMultipleSelection = YES;
}
Done Button is called ---
- (IBAction)DonePressed:(id)sender {
[self dismissViewControllerAnimated:YES completion:nil];
id<FilterProtocol> strongDelegate = self.delegate;
if ([strongDelegate respondsToSelector:#selector(GetTheSet:)]) {
[strongDelegate GetTheSet:self.selectStates];
}
}
#end
You can keep those elements in NSUserDefaults, and whenever DemoTableViewController appears, you send [tableView reloadData]. Do this in the viewDidAppear: method.
You can also use Core Data, but there are a lot of details to explain how to do that.
After a lot of trial and error i come to know that in BrandsTVC--
- (IBAction)DonePressed:(id)sender {
NSLog(#"done pressed %#",self.delegate);
[delegate GetTheSet:self.selectStates];
}
self.delegate is giving me NULL.
delegate is not setup and i cant figure out how to do that.. someone help me..
this answer solved my problem :D
custom viewcontroller delegate not working
I am trying to access an array defined as property on the parent view from child view and I get an empty array. here is what I did. could someone shed some light please!
FirstTableViewController.h
#interface FirstTableViewController : UITableViewController
#property (nonatomic,retain) NSMutableArray *SomeItems;
#end
in my FirstTableViewController.m. I have code that initialized the SomeItems with values. This has been verified
On the FirstTableViewController view there is a button that displays a second SecondTableView
in SecondTableViewController.m I have
#import "FirstTableViewController.h"
#import "SecondTableViewController.h"
- (void)viewDidLoad
{
[super viewDidLoad];
FirstTableViewController * objParent;
NSLog(#"count = %i",[objParent.SomeItems count]); //this return 0
}
thanks in advance!
EDITED
ToDoListTableViewController.h
#interface ToDoListTableViewController : UITableViewController
#property (nonatomic, strong) NSMutableArray *toDoItems;
- (IBAction)unwindToList:(UIStoryboardSegue *)segue : (id) sender;
#end
ToDoListTableViewController.m
- (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
//Attempt to pass toDoItems to new view controller.
//CompleteTableViewController.toDoItems = [self.toDoItems copy]; //this line caused compiler error saying toDoItems not found on object of CompleteTableViewController
CompleteTableViewController * objChild = (CompleteTableViewController*)[segue destinationViewController];
if(objChild != nil)
objChild.toDoItems = [self.toDoItems copy];
//sorry for weird code, as I don't really understand how this method really works.
//but I have a feeling I am just some inches away from getting it to work the way i want
}
CompleteTableViewController.h
#interface CompleteTableViewController : UITableViewController
#property (nonatomic,copy) NSMutableArray *toDoItems;
#end
CompleteTableViewController.m
- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(#"#%i record(s) in Complete Table View", [toDoItems count]);
}
Thanks again!
It is clear that you miss the basilar concept of the OOP.
You declared this:
FirstTableViewController * objParent;
but first of all it is not initializated and second it doesn't point to your instanced viewController.
Other things but that at this point become secondary are:
if you are using ARC, declare the property strong instead of retain;
method and variable should respect the Camel methodology so is not SomeItems but is someItems;
So if you are opening a viewController from another and you want access to that array, the best thing that you could do is pass that array and so have a property like this also in the second viewController:
#property (nonatomic,copy) NSArray *someItems;
and when you press the button in the first viewController, before push the second viewController:
secondViewController.someItems = [self.someItems copy];
Note that in the second view controller the array is not mutable, because probably you want just access to the informations. But this depend from you.
Is a little bit hard explain you more because i see that you are really a newbie. But, i hope to help you.
You need to pass a reference for the parent object through to the child on creation, or simply pass a reference to the array itself.
From Matteo suggestion, this seems to solve my issue
- (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
UINavigationController *navigationController = segue.destinationViewController;
CompleteTableViewController *objChild = (CompleteTableViewController *)navigationController.topViewController;
if(objChild != nil){
objChild.toDoItems = [self.toDoItems copy];
}
}
thanks Matteo.
In the SecondTableViewController, you've declared the FirstTableViewController in viewDidLoad, but that does not mean it's pointing to your previously created FirstTableViewController (you've made no assignment). Before viewDidLoad is called, you need to pass the FirstTableViewController to the SecondTableViewController, assign it to a variable that's not local in scope, and then you can access the FirstTableViewController and/or its SomeItems inside viewDidLoad.
Without knowing more of your design or what you're trying to accomplish, it'd be best to pass SomeItems to SecondTableViewController as part of initializing it if that's all you need from FirstTableViewController. If the state of what you're accessing is going to change as you are going from controller to controller, I'd highly recommend you spend more time reading up on Model-View-Controller (MVC), delegation and possibly Key-Value Observation (KVO). You're missing some fundamental knowledge.
Edit: also agree on naming, SomeItems should be someItems.
I have been searching all morning how to do this. I have 2 View Controllers. From the root View Controller (ViewControllerA - which is a table view controller) you can go push to the second view controller (ViewControllerB).
In the ViewControllerB, there are two fields: contacts & textBody. When the user is done they can click on "Add". This will then go back to ViewControllerA. What I am trying to do now, is for every time that process occurs, all the information from ViewControllerB the user just added goes into a cell in ViewControllerA. The user can then add as many cells as they like.
What I can't do however, is get the information across the view controllers. I have been looking all morning at using the app delegate, singletons??, protocols, sharing properties, etc! But I am still stuck.
What I want to do, but can't, is for every time the user clicks "Add" on ViewControllerB, contacts & texts are put into an array. This array is then put into another array which holds all the smaller arrays which the user has created? If you have an ideas, or links to similar/sample code or tutorials, that would be much appreciated!
Try this using the delegate method as follows
Download Sample Project with XIBs
Download Sample Project With Storyboard
ParentViewController.h
#import <UIKit/UIKit.h>
#interface ParentViewController : UIViewController {
NSMutableArray *dataArray;
}
- (void)passData:(NSMutableArray *)array;
#end
ParentViewController.m
#import "ParentViewController.h"
#import "ChildViewController.h"
#implementation ParentViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Initialise the mutable array.
dataArray = [[NSMutableArray alloc] init];
}
- (IBAction)btnGoToSecondView:(id)sender {
ChildViewController *secondVC = [[ChildViewController alloc] initWithNibName:#"ChildViewController" bundle:nil];
secondVC.delegate = self;
[self presentViewController:secondVC animated:YES completion:nil];
}
- (void)passData:(NSMutableArray *)array {
[dataArray addObject:array];
NSLog(#"Data Passed = %#",dataArray);
}
#end
ChildViewController.h
#import <UIKit/UIKit.h>
#import "ParentViewController.h"
#class ParentViewController;
#interface ChildViewController : UIViewController {
NSMutableArray *tempArray;
}
#property (strong, nonatomic) IBOutlet UITextField *txtContact;
#property (strong, nonatomic) IBOutlet UITextField *txtTextBody;
#property(nonatomic, assign) ParentViewController *delegate;
#end
ChildViewController.m
#implementation ChildViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Initialise the mutable array.
tempArray = [[NSMutableArray alloc] init];
}
- (IBAction)btnPassDataBack:(id)sender {
if([self.delegate respondsToSelector:#selector(passData:)]) {
[tempArray addObject:_txtContact.text];
[tempArray addObject:_txtTextBody.text];
[self.delegate passData:tempArray];
}
[self dismissViewControllerAnimated:YES completion:nil];
}
- (void)viewDidUnload {
[self setTxtContact:nil];
[self setTxtTextBody:nil];
[super viewDidUnload];
}
#end
With Storyboard
If you are using storyboard then create a ParentViewController segue ChildViewController and give it a identifier in my sample it showChildView
Then use the following code to set the delegate
// Calling the segue to go to the child view and setting up the delegate.
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"showChildView"]) {
ChildViewController *childVC = segue.destinationViewController;
childVC.delegate = self;
}
}
Then to dismiss back to the ParentViewController use the following code (from my sample)
- (IBAction)btnPassDataBack:(id)sender {
if([self.delegate respondsToSelector:#selector(passData:)]) {
[tempArray addObject:_txtContact.text];
[tempArray addObject:_txtTextBody.text];
[self.delegate passData:tempArray];
}
[self.navigationController popToRootViewControllerAnimated:YES];
}
I would recommend using a singleton instance of your NSMutableDictionary as they have bailed me out of your exact situation multiple times (including custom frameworks and UITabBarControllers). Here is an example I'm currently using to implement a singleton. This methodology is also ARC-safe as well
mySingleton.h
#import <Foundation/Foundation.h>
#interface mySingleton : NSObject {
}
+ (NSMutableDictionary *) myMutableDict;
#end
mySingleton.m
#import "mySingleton.h"
#implementation mySingleton
+ (NSMutableDictionary *)myMutableDict
{
static NSMutableDictionary *singletonInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
singletonInstance = [[NSMutableDictionary alloc]init];
});
return singletonInstance;
}
#end
As long as you include mySingleton.h in all of your view controllers you can access the data via [mySingleton myMutableDict]. For example: [[mySingleton myMutableDict] setObject:myObject forKey:myKey];
Good luck!
If the information is really "global" - it has only one instance across the whole app - then you should create a singleton as DB80Buckeye suggested.
If the information is something that truly belongs to ViewController1 and you want it to be modified in ViewController2 (ie ViewController2 is really part of ViewController1, it just happens to be on another screen), then you should pass that as part of the constructor of ViewController2.
-(void)view_controller_1_that_push_view_controller_2_onto_the_stack {
ViewController2* vc2 = [[ViewController2 alloc] initWithInformation:your_information];
[self.navigationController pushViewController:vc2 animated:YES];
}
#interface ViewController2
-(id)initWithInformation:(YourInformationClass*)info;
#end
Another way is to use notifications.
There are two ways to go here. The standard pattern for doing this is delegation. You don't need a singleton. ViewControllerA manages and lists your data. ViewControllerB doesn't need to know anything about all of that data so there's no reason to expose it via a singleton, etc.
Create a delegate protocol in ViewControllerB's header file. Something like this:
#protocol ViewControllerBDelegate
- (void)addContact:(NSString *)contact withBody:(NSString *)textBody;
#end
Now, specify that ViewControllerA will implement the delegate protocol in its header:
#interface ViewControllerA : UIViewController <ViewControllerBDelegate>
Don't forget to import ViewControllerB.h at the top of ViewControllerA's header.
In ViewControllerA's implementation, implement the delegate method you specified in the protocol:
- (void)addContact:(NSString *)contact withBody:(NSString *)textBody {
[self.someArray addObject:[[SomeObject alloc] initWithContact:contact body:textBody]];
[self.tableView reloadData];
}
That's obviously just an example -- not sure how you're managing your data structure and it's probably better to insert the cell someplace that makes sense.
Declare a delegate reference in ViewControllerB's header:
#property (weak, nonatomic) id<ViewControllerBDelegate> delegate;
When you present ViewControllerB, set ViewControllerA as the delegate.
ViewControllerB *b = [[ViewControllerB alloc] init...];
b.delegate = self;
In the selector triggered by the add button in ViewControllerB, call back on the delegate before popping the view controller off the navigation stack:
[self.delegate addContact:contact withBody:text];
where contact and text are the values the user entered.
One could also use a block instead of a delegate but the principle is the same -- have the second view controller only be responsible for taking input, in your case, and pass it back to the view controller managing the data.
Alternatively for delegate suggest using the following:
ViewControllerA.h:
#property (nonatomic, strong) ViewControllerB* viewControllerB;
In ViewControllerA.m
if (!self.viewControllerB)
{
self.viewControllerB = [[ViewControllerB alloc] initWithNibName: #"ViewControllerBr" bundle: nil];
}
[self.navigationController pushViewController: self.viewControllerB
animated: YES];
...
- (void) viewWillAppear: (BOOL) animated
if (self.viewControllerB)
{
NSString* contact = self.viewControllerB.contact;
NSLog(#"%#", contact);
}
...
I have a tableViewController that I will present once in a while.
I have created it as a property, on .h
myTVC *myTable;
and
#property (nonatomic, retain) myTVC *myTable;
then, on .m I have synthesized it and created a getter
#synthesize myTable = _myTable;
and
- (myTVC *) myTable {
if (_myTable == nil) {
_myTable = [[myTVC alloc] init];
}
return _myTable;
}
when it is time to use I simply do
[self presentModalViewController:myTable animated:YES];
[myTable release];
as far as I thought, myTable's getter would run at this point and allocate the tableViewController, but it is not running and the app crashes telling me that I am trying to present a nil tableViewController...
What am I missing? Thanks.
you need to do self.myTable if you do myTable you are asseccing your iVar that is call myTable into which your #property is not store, because you are doing this : #synthesize myTable = _myTable; which will create an iVar call _myTable.
So you are doing 2 wrongs things in here.
To correct your code do the following :
remove this line : myTVC *myTable;
and do [self presentModalViewController:self.myTable animated:YES];
A 3rd thing is also strange in your code
[self presentModalViewController:myTable animated:YES];
[myTable release]; // <---- this line, remove it to
I'm not sure why that line is there since you are storing your controller in a #property.
and a 4th By the way
The default initializer for a UIViewController is the following
- (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)nibBundle
You can pass nil if you don't have a .xib to go with it.
In
[self presentModalViewController:myTable animated:YES];
[myTable release];
You're not actually calling the myTable method.
Do
self.myTable = [self myTable]
first. Though I don't see why you need a myTable method instead of just doing an alloc init.