Object is nil when called from another class - iphone

I want to change properties of another object, when a method is called in another class.
The code to change the properties of this object sits in a method of the first class, and works when calling it from it's own class, but when called from the other class the object in the method returns nil.
Here is the code:
ViewController.h
#interface ViewController : UIViewController {
UIView *menuView; //the object
}
#property (nonatomic, retain) IBOutlet UIView *menuView;
-(void)closeMenu; //the method
#end
ViewController.m
#implementation ViewController
#synthesize menuView;
-(void)closeMenu{
[menuView setFrame:CGRectMake(menuView.frame.origin.x, -menuView.frame.size.height, menuView.frame.size.width, menuView.frame.size.height)];
NSLog(#"%f", menuView.frame.size.height); //returns height when method is called from it's own class. But returns 0 (nil) when called from the other class.
}
SDNestedTableViewController.h (nothing too important, but might help?)
#interface SDMenuViewController : SDNestedTableViewController{
}
SDNestedTableViewController.m
#import "SDMenuViewController.h"
#import "ViewController.h"
- (void) item:(SDGroupCell *)item subItemDidChange:(SDSelectableCell *)subItem
{
ViewController *firstViewController = [[[ViewController alloc] init] autorelease];
SelectableCellState state = subItem.selectableCellState;
NSIndexPath *indexPath = [item.subTable indexPathForCell:subItem];
switch (state) {
case Checked:
NSLog(#"Changed Sub Item at indexPath:%# to state \"Checked\"", indexPath);
[firstViewController closeMenu]; //called from other class
break;
case Unchecked:
NSLog(#"Changed Sub Item at indexPath:%# to state \"Unchecked\"", indexPath);
break;
default:
break;
}
}

What you posted looks like:
-(void)closeMenu{
// menuView is never initialized, == nil
[nil setFrame:CGRectMake(0, -0, 0, 0)];
NSLog(#"%f", 0); //returns height when method is called from it's own class. But returns 0 (nil) when called from the other class.
}
So you are doing NSLog(#"%f", 0);.
If you do load the view by accessing the view property, the menuView will be initialized by IB rules.
For the details of viewController view loading/unloading see the reference docs.

I think this may help you.
At Your AppDelegate class, you have to declare an object of ViewController class. Make it as a property of the YourAppDelegate class. like below. (This would import ViewController class and creates a shared object of YourAppDelegate class so that you can access the members of YourAppDelegate class globally by simply importing the YourAppDelegate.h).
#import "ViewController.h"
#define UIAppDelegate ((YourAppDelegate *)[UIApplication sharedApplication].delegate)
#interface YourAppDelegate : NSObject <UIApplicationDelegate>
{
ViewController *objViewController;
}
#property (nonatomic, retain) ViewController *objViewController;
#end
And synthesize the property at YourAppDelegate.m file.
#implementation YourAppDelegate
#synthesize objViewController;
#end
Then the tricky part is, you have to backup the object of ViewController class in the YourAppDelegate class at the time you are loading the ViewController class.
For that first import the YourAppDelegate.h in the ViewController.h class and at the ViewController.m implement viewWillAppear: delegate as follows.
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
UIAppDelegate.objViewController = self;
}
Then at SDNestedTableViewController.m,
#import "SDMenuViewController.h"
#import "ViewController.h"
- (void) item:(SDGroupCell *)item subItemDidChange:(SDSelectableCell *)subItem
{
ViewController *firstViewController = (ViewController *)UIAppDelegate.objViewController;
if(firstViewController && [firstViewController isKindOfClass:[ViewController class]])
{
SelectableCellState state = subItem.selectableCellState;
NSIndexPath *indexPath = [item.subTable indexPathForCell:subItem];
switch (state) {
case Checked:
NSLog(#"Changed Sub Item at indexPath:%# to state \"Checked\"", indexPath);
[firstViewController closeMenu]; //called from other class
break;
case Unchecked:
NSLog(#"Changed Sub Item at indexPath:%# to state \"Unchecked\"", indexPath);
break;
default:
break;
}
}
}
Try this way. I am not saying this as the right way but, this should works. Glad if this helps you.

EDIT 2:
Well, you shipped your code over to me, so now I can no longer say that I don't have enough information to solve your problem.
Let's see.
Now I see that your ViewController is the rootViewController of your app, like so:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
// Override point for customization after application launch.
self.viewController = [[[ViewController alloc] initWithNibName:#"ViewController" bundle:nil] autorelease];
self.window.rootViewController = self.viewController;
[self.window makeKeyAndVisible];
return YES;
}
Good, now how does the ViewController relate to your SDNestedTableViewController?
You have this in your ViewController's viewDidLoad:
- (void)viewDidLoad
{
[super viewDidLoad];
SDMenuViewController *mvc = [[[SDMenuViewController alloc] initWithNibName:#"SDNestedTableView" bundle:nil] autorelease];
[self addChildViewController:mvc];
[mvc didMoveToParentViewController:self];
[menuView addSubview:mvc.view];
// Some other stuff with gesture recognizers I'm omitting...
[self openMenu];
}
Alright, so it looks like SDMenuViewController is the child of ViewController. Now, you have a method in SDMenuViewController called item:subItemDidChange:
- (void) item:(SDGroupCell *)item subItemDidChange:(SDSelectableCell *)subItem
{
ViewController *firstViewController = [[[ViewController alloc] initWithNibName:#"ViewController" bundle:nil] autorelease];
SelectableCellState state = subItem.selectableCellState;
NSIndexPath *indexPath = [item.subTable indexPathForCell:subItem];
switch (state) {
case Checked:
NSLog(#"Changed Sub Item at indexPath:%# to state \"Checked\"", indexPath);
//close the menuView
[firstViewController closeMenu];
break;
case Unchecked:
NSLog(#"Changed Sub Item at indexPath:%# to state \"Unchecked\"", indexPath);
break;
default:
break;
}
}
So, you want the reference back to the existing ViewController object, right? Because right there you're making another one. So, you can do this:
ViewController *firstViewController = self.parentViewController;
That gets you a reference to SDMenuViewController's parent, which is the instance of ViewController. This property is set when you do your addChildViewController: call.
Okay, this is confusing though:
In your post, you say that your item:subItemDidChange: method is in SDNestedTableViewController, but in the code you sent me it's in the SDMenuViewController.
In the SDNestedTableViewController, I found this method:
- (void) mainItem:(SDGroupCell *)item subItemDidChange: (SDSelectableCell *)subItem forTap:(BOOL)tapped
{
if(delegate != nil && [delegate respondsToSelector:#selector(item:subItemDidChange:)] )
{
[delegate performSelector:#selector(item:subItemDidChange:) withObject:item withObject:subItem];
}
}
So it looks like you're not using the same code as in the original post, but close enough, whatever.
Now, if you want to get a reference to the ViewController instance from anywhere in the app, not just your SDMenuViewController (which happens to be the child of the ViewController instance) you should use #Mathew Varghese's answer.
Here's a restatement of this method:
Add the line + (AppDelegate *)instance; to your AppDelegate.h file.
Add the following method to your AppDelegate.m file.
Like so:
+ (AppDelegate *)instance
{
AppDelegate *dg = [UIApplication sharedApplication].delegate;
return dg;
}
Then, in whatever object you want that reference, you #import AppDelegate.h and say ViewController *vc = AppDelegate.instance.firstViewController;
Anyway, it's just another way of saying what Mathew mentioned earlier.

the problem is:
- (void) item:(SDGroupCell *)item subItemDidChange:(SDSelectableCell *)subItem {
ViewController *firstViewController = [[[ViewController alloc] init] autorelease];
...
[firstViewController closeMenu];
}
When you call closeMenu from there, it is never initialized, because not enough time has passed to initialize view of view controller, viewDidLoad method of your firstViewController is not called at this point either. menuView is not created from nib either, so this is the reason why it is nil.
Maybe for some reason there might be a delay long enough so menuView is created, but this is not how you should do things in iOS.
So, if you don't want to show your menuView, just add some boolean value to your firstViewController and instead of closeMenu do:
firstViewController.shouldCloseMenu = YES;
Then in your ViewController in viewDidLoad method do something like:
if (self.shouldCloseMenu ) {
[self closeMenu];
}
Maybe this is not the best way to do it, but now you have an idea how it suppose to work.

I believe your problem is the related to the way you have initialized the viewController.
Instead of
ViewController *firstViewController = [[[ViewController alloc] init] autorelease];
use
ViewController *firstViewController = [[[ViewController alloc] initWithNibName:#"yourNibName" bundle:nil] autorelease];
I'm assuming you have a nib because you are using an IBOutlet. But I believe the IBOutlet is never setup because you have not loaded the nib file.
Also double check your IBOutlet connection with interface builder and use "self.menuView"

I would suggest you to solve this problem in the following steps.
Do not use any instance or variable of firstViewController in the SDMenuViewController.
In the case check block, post a message to the NSNotificationCenter
In the ViewController register the message with the same message Id, use the closeMenu method as its handler.
For me, use the message center to dispatch the handling can decouple the relationship between controllers. This is a better way that you would concern less about the lifecycle of the controller within another one.
Hope it would be helpful.

There is a difference between alloc-init'ing a ViewController and alloc-init'ing that view controller's properties.
Regarding your second example (calling from another class). Your current code indicates that you alloc-init firstViewController, but then don't do anything with it. Assuming you have not overriden your ViewController's init method, its properties and iVars should be nil (or undefined at worst). You need to alloc-init your firstViewController.menuView first. I.e:
firstViewController.menuView = [[UIView alloc] initWithFrame]; // Don't do this.
The problem with this approach is that you're setting up firstViewController's properties form another class, and that's generally fairly average design practice. This required setup would usually happen in viewDidLoad but because you haven't done anything with firstViewController yet, it never gets called.
In contrast, when you call closeMenu from its own View Controller, the odds are you are actually doing something with the view and viewDidLoad (or wherever menuView = [[UIView alloc] init];is found) is called first, thus initialising your menuView object.
You need to ensure that your menuView object is initialised first before you try and do anything with it, just initialising the View Controller that contains it is not enough.

#import "SDMenuViewController.h"
#import "ViewController.h"
- (void) item:(SDGroupCell *)item subItemDidChange:(SDSelectableCell *)subItem
{
// why are we allocating this object here, if it is only required in case Checked :
ViewController *firstViewController = [[[ViewController alloc] init] autorelease];
SelectableCellState state = subItem.selectableCellState;
NSIndexPath *indexPath = [item.subTable indexPathForCell:subItem];
switch (state) {
case Checked:
NSLog(#"Changed Sub Item at indexPath:%# to state \"Checked\"", indexPath);
[firstViewController closeMenu]; //called from other class
break;
case Unchecked:
NSLog(#"Changed Sub Item at indexPath:%# to state \"Unchecked\"", indexPath);
break;
default:
break;
}
}
Change it to
#import "SDMenuViewController.h"
#import "ViewController.h"
- (void) item:(SDGroupCell *)item subItemDidChange:(SDSelectableCell *)subItem
{
// why are we allocating this object here, if it is only required in case Checked :
SelectableCellState state = subItem.selectableCellState;
NSIndexPath *indexPath = [item.subTable indexPathForCell:subItem];
switch (state) {
case Checked:
NSLog(#"Changed Sub Item at indexPath:%# to state \"Checked\"", indexPath);
// here no need to put object in autorelease mode.
ViewController *firstViewController = [[ViewController alloc] init];
[firstViewController closeMenu]; //called from other class
[firstViewController release];
break;
case Unchecked:
NSLog(#"Changed Sub Item at indexPath:%# to state \"Unchecked\"", indexPath);
break;
default:
break;
}
}

try to remove UIView *menuView; //the object from the interface file
#interface ViewController : UIViewController {
// try to remove this line
UIView *menuView; //the object
}
and update this method
-(void)closeMenu{
[self.menuView setFrame:CGRectMake(self.menuView.frame.origin.x, -self.menuView.frame.size.height, self.menuView.frame.size.width, self.menuView.frame.size.height)];
NSLog(#"%f", self.menuView.frame.size.height);
}

Everything is correct, change the -(void)closeMenu method like...
-(void)closeMenu
{
menuView=[[UIView alloc]initWithFrame:CGRectMake(50.0,50.0,200.0,200.0)]
NSLog(#"%f", menuView.frame.size.height); //returns height when method is called from it's own class. But returns 0 (nil) when called from the other class.
}
Try this and let me know.

I suggest you use this:
if(menuView) {
[menuView setFrame:CGRectMake(menuView.frame.origin.x, -menuView.frame.size.height, menuView.frame.size.width, menuView.frame.size.height)];
} else {
NSLog(#"menuView is nil");
}

Related

UIPageViewController check when swiped back or forward

I want to keep track of the index using the UIPageViewController. Whenever I swipe I need to index++ or index--. This delegate method gets called whenever you swipe back or further:
- (void)pageViewController:(UIPageViewController *)pvc didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
// If the page did not turn
if (!completed)
{
// You do nothing because whatever page you thought
// the book was on before the gesture started is still the correct page
return;
}
// I want to check here whenever the page was swiped back or further
}
How do I check in this method if the user swiped back or further? I know there are the 2 DataSource methods "viewControllerAfterViewController" and "viewControllerBeforeViewController" but I cannot check if the page transition has completed (and I can do this in the above method) any idea how I could know if the user swiped back or further in the above method?
use protocol:
MyClass : UIViewController <UIPageViewControllerDataSource,UIPageViewControllerDelegate
declare a atributes:
#property(nonatomic) NSInteger currentIndex;
#property(nonatomic) NSInteger nextIndex;
and in the methods:
-(void)pageViewController:(UIPageViewController *)pageViewController willTransitionToViewControllers:(NSArray *)pendingViewControllers{
NewsTableViewController *controller = [pendingViewControllers firstObject];
self.nextIndex = [self.arrViews indexOfObject:controller];
}
-(void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed{
if (completed) {
self.currentIndex = self.nextIndex;
}
self.nextIndex = 0;
}
there you will have the current page.
Thanks to Corey Floyd in enter link description here
According to the documentation there does not appear to be a way to tell whether the user has swiped the page forward or backward. The boolean 'finished' will tell you whether or not the user has completed the page turn.
A workaround:
Create an int variable and using the viewControllerAfterViewController and viewControllerBeforeViewController methods either increase or decrease the value of the variable. Use that to test whether or not they moved forward or backward.
Edit: You could use presentationIndexForPageViewController from the documentation
Edit 2: Check this link here There is a method named setViewControllers:direction:animated:completion: the direction will be either UIPageViewControllerNavigationDirectionForward or UIPageViewControllerNavigationDirectionReverse
Edit 3: Code - This is assuming you know which view controller will be called by either going forward or backward:
Create a variable on your appDelegate and a setter method:
int indexVar;
- (void)setIndex:(int)indexVar;
Then on your view controllers (forward or backward) either increase the value or decrease the value (viewDidLoad):
(AppDelegate *)[[UIApplication sharedApplication] delegate] setIndex:<whatever>];
Something along those lines. This won't be an exact way to accomplish your goal, but hopefully it will get you headed in the right direction.
I did it by creating protocols in each of my ViewController classes, with the protocol method called in the viewWillAppear method. Then in the PageViewController whenever I instantiate one of the view controllers I set its delegate to be the PageViewController.
This is the 3rd ViewController in my project(Note that I've done this in each of my view controllers)
#class ViewController3;
#protocol ViewControllerPageNumber <NSObject>
-(void)viewWillAppearMyPageNumber:(int)myPageNumber;
#end
#interface ViewController3 : UIViewController
#property (nonatomic, weak) id <ViewControllerPageNumber> delegate;
#end
and in the .m file in the viewWillAppear method
-(void)viewWillAppear:(BOOL)animated{
[self.delegate viewWillAppearMyPageNumber:3];//The 3 will be different for each ViewController
}
Next, in the PageViewController.m, whenever I instantiate a view controller I set its delegate to be self( or PageViewController). viewCons is just an array of strings with my viewControllers names.
- (UIViewController *)viewControllerAtIndex:(NSUInteger)index {
id vc = [[NSClassFromString([viewCons objectAtIndex:index]) alloc] init];
if([vc isMemberOfClass:[NSClassFromString(#"ViewController3") class]]){
ViewController3 *vc3=(ViewController3 *) vc;
vc3.delegate=self;
}else if([vc isMemberOfClass:[NSClassFromString(#"ViewController2") class]]){
ViewController2 *vc2=(ViewController2 *) vc;
vc2.delegate=self;
}else if([vc isMemberOfClass:[NSClassFromString(#"ViewController") class]]){
ViewController *vc1=(ViewController *) vc;
vc1.delegate=self;
}
return vc;
}
Finally, I'm implementing my custom delegate method, which in my case is refreshing labels' text I have set on top of the PageViewController.
-(void)viewWillAppearMyPageNumber:(int)myPageNumber{
[self refreshLabelsOnCurrentPageWithIndex:myPageNumber];
}
I think the easiest solution is to to create an own ViewController class with a property that keeps track of the currently shown index. In most of the cases I need a custom ViewController for my PageViewController anyways. In my example this is the following class.
#interface PageZoomViewController : UIViewController
#property (nonatomic) int pageIndex;
#end
Then in the viewControllerAfter/Before methods you can pass the index to the new page.
-(UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
int nextPageIndex = ((PageZoomViewController *)viewController).pageIndex-1;
PageZoomViewController *controller = [[PageZoomViewController alloc] initWithPageViewControlParent:self andFrame:[self frameForPagingScrollView] andPageIndex:nextPageIndex];
return controller;
}
When the animation for the next page finished you can easily set the current index like this.
-(void)pageViewController:(UIPageViewController *)thePageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed {
if(completed) {
index = ((PageZoomViewController *)thePageViewController.viewControllers[0]).pageIndex;
}
}
Hope this helps!

it possible to Pass Data with popViewControllerAnimated?

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);
}

Calling a viewcontroller another class from connectiondidfinish delegate NSURLConnection

Trying to launch a viewcontroller in connectiondidfinish delegate method of NSUrlConection
//Sprequest.m inherited from nsobject
- (void)connectionDidFinishLoading:(NSURLConnection *)conn {
NSLog(#"connectionDidFinishLoading ");
if(nStatus == 401)
{
NSLog(#"called maincontroller to launch dvrview");
MainController *mainview =[[MainController alloc] init];
[mainview reponseFromServer];
}
}
//maincontroller.m from viewcontroller
-(void)reponseFromServer
{
NSLog(#"response from server - main controller ");
dvrView *dvrObj = [[dvrView alloc]initWithNibName:#"dvrView" bundle:nil];
[self.navigationController pushViewController:dvrObj animated:YES];
}
this dvr view doesnt get loaded
Sprequest.m is inherited from NSObject , its not a viewController subclass so you cant use
[self.navigationController pushViewController:dvrObj animated:YES];
inside Sprequest.m
You can get the navigationController object from the appdelegate like this
((AppDelegate *)[UIApplication sharedApplication].delegate).navigationController
then use
[((AppDelegate *)[UIApplication sharedApplication].delegate).navigationController pushViewController:dvrObj animated:YES];

Need Help with applicationDidBecomeActive

I have been trying for days to get this code to work, but I have no idea what I am doing wrong. Everytime the app wakes up from sleep, or the user closes the app and opens it again (without closing the app from multitasking), I want a label value to change.
In my applicationDidBecomeActive, I am running a counter, which I want to display on whatever viewcontroller is open at that moment.
Code:
- (void)applicationDidBecomeActive:(UIApplication *)application {
counter = counter + 1;
W1G1 *view1 = [[[W1G1 alloc] initWithNibName:#"W1G1" bundle:nil] retain];
[view1 setlabel];
}
In my viewcontroller W1G1, I have the following code:
Code:
- (void) setlabel {
NSString *string = [NSString stringWithFormat:#"%d", counter];
vocabword.text = string;
}
I have imported W1G1 in my appdelegate, but the code does not run :( Please help!
Thanks
In the AppDelegate.m file, where you have
- (void)applicationDidBecomeActive:(UIApplication *)application {
counter = counter + 1;
W1G1 *view1 = [[[W1G1 alloc] initWithNibName:#"W1G1" bundle:nil] retain];
[view1 setlabel];
}
the variable counter being incremented is confined to the AppDelegate. In other words, your view controller doesn't know that it has been incremented.
I would suggest that you use NSUserDefaults to store the value of counter so that you can easily pass it between these view controllers. Either that, or you could allow for an input into the method setLabel, e.g.
- (void) setlabel:(int)counter {
NSString *string = [NSString stringWithFormat:#"%d", counter];
vocabword.text = string;
}
and then in the AppDelegate you'll want to do:
- (void)applicationDidBecomeActive:(UIApplication *)application {
counter = counter + 1;
W1G1 *view1 = [[[W1G1 alloc] initWithNibName:#"W1G1" bundle:nil] retain];
[view1 setlabel:counter]; // <-- now you're using counter
[self.window addSubview:view1];
}
1) When you say 'the code does not run' do you mean that? That is, if you put NSLogs in applicationDidBecomeActive: and in setLabel does it show the code is run?
2) I would suspect the code is running. But your code won't "show the counter on whatever view controller is open at that moment". Your code creates a new view (view1), but that view won't be displayed. It is not added as a subview to anything. Your code will also leak. You create a W1G1 object, but it is never released and you throw away any reference you have to it.
To achieve what you want, you could add a subview to the application's window. Depending how your app delegate is set up, something like the following should do the trick:
counter++;
W1G1 *viewController1 = [[W1G1 alloc] initWithNibName:#"W1G1" bundle:nil];
[viewController1 setlabel: counter];
[[self window] addSubview: [viewController1 view]]
// you'll want to save a reference to the viewController somehow so you can release it at a later date
Then in W1G1
- (void) setlabel: (int) counter;
{
NSString *string = [NSString stringWithFormat:#"%d", counter];
vocabword.text = string;
}
There are, of course, lots of other approaches you could take towards this problem. And you'll need some strategy for removing the W1G1 view that you are adding at some stage, otherwise you'll just get more and more views added.
Update: You ask (in comments) how to keep track of your viewController throughout lifetime of the app... One approach is to keep track of it in your appDelegate. In the header have something like:
#class W1G1;
#interface MyAppDelegate : : NSObject <UIApplicationDelegate>
{
// other decelerations
int counter;
W1G1 * _myW1G1
}
#property (nonatomic, retain) W1G1* theW1G1
In the .m file include
#synthesize theW1G1 = _myW1G1;
Probably in application:didFinishLaunchingWithOptions: create the viewController, set the property to refer to it, and add its view to the view hierarchy.
W1G1* theViewController = [[W1G! alloc] initWithNibName: #"W1G1" bundle: nil];
[[self window] addSubview: [theViewController view]];
[self setTheW1G1: theViewController];
[theViewController release];
Then when you want to access the viewController again from with the app delegate use [self theW1G1], e.g.
[[self W1G1] setlabel: counter];

RootViewController - iPhone

I am new to iPhone programming and trying to grasp the concept of RootViewController.
Scenario:
I have 3 views
RootViewController - Parent View
SportsViewController - Sub View 1
CricketViewController - Sub View 2
Both the subview have to be in FullScreenMode, so tab-bar or navigation bar cannot be used.
At first, Sub View 1 is loaded which is having some content and a DONE button on it.
Once user press DONE button then Sub View 1 has to be unloaded and RootViewController should load the Sub View 2.
Query
I have successfully displayed SubView 1 and when user taps on DONE then I can unload it. But I did n't get how should I notify the RootViewController from Sub View 1 that Sub View 1 has unloaded and now it should load the Sub View 2?
Thanks in Advance
Paras Mendiratta
I think the easiest solution here is to use UINavigationController and just hide the navigation bar. You can use -setNavigationBarHidden:animated: to hide (or show) the nav bar.
one way is to implement a method like - (void)loadSecondView which does all u want to do when first view is unloaded. and then int doneButtonClicked-method u call this method like this: [super loadSecondView]; and also remove first view from superview.
I assume that the screen with the "Done" button is some kind of login screen. You actually do not need all the view controllers you have defined to do what you want.
Instead you could do like this:
At application launch set CricketViewController as the root view controller.
Immediately let CricketViewController present `SportsViewController" as a modal view controller, no animation.
As far as the user is concerned the sports view controller is the starting point.
Dismiss the modal view controller on the Done button tap, giving the user the illusion of going to the next view.
view1 = [[View1 alloc] initWithNibName:#"View1" bundle:nil]; //Create the first view
UINavigationController *navigationController1 = [[UINavigationController alloc] initWithRootViewController:view1];
navigationController1.navigationBar.tintColor =[UIColor blackColor];
view1 = navigationController1;
[window addSubview:view1.view];
[window makeKeyAndVisible];
This is general idea so please change according to your problem.
Here is my code where I tried to use delegate pattern.
The problem is the sub view 1 (videoPlayer) is not able to call the delegate methods. :(
ViewSwitcher.h - Root Controller
#class VideoPlayer; //Sub View 1
#class LandingPage; //Sub View 2
#protocol viewSwitcherDelegate
-(void)notifyViewSwitcher;
#end
#interface ViewSwitcher : UIViewController
{
id <viewSwitcherDelegate> delegate;
}
#property (nonatomic, retain) VideoPlayer *videoPlayer;
#property (nonatomic, retain) LandingPage *landingPage;
#property(assign) id <viewSwitcherDelegate> delegate;
-(void)loadSecondView;
-(void)delegateSetInSubView;
#end
ViewSwitcher.m - Implementation
#synthesize videoPlayer;
#synthesize landingPage;
//#synthesize delegate;
// 1.4 -> Declare the delegate constructor
- (id <viewSwitcherDelegate>)delegate
{
return delegate;
}
// 1.5 -> Declare the setDelegate method
- (void)setDelegate:(id <viewSwitcherDelegate>)v
{
delegate = v;
}
- (void)viewDidLoad
{
VideoPlayer *videoController = [[VideoPlayer alloc] initWithNibName:#"VideoPlayer" bundle:nil];
self.videoPlayer = videoController;
[self.view insertSubview:videoController.view atIndex:0];
[videoController release];
[super viewDidLoad];
}
-(void)loadSecondView
{
NSLog(#"Call for loading 2nd View");
}
VideoPlayer.h - SubView 1 (Movie Player)
#interface VideoPlayer : UIViewController <viewSwitcherDelegate>
{
ViewSwitcher *viewSwitcher;
MPMoviePlayerController *videoController;
}
#end
VideoPlayer.m - implementation
-(void)notifyViewSwitcher
{
NSLog(#"notifyViewSwitcher called.");
//Attempted to call the loadSecondView of ViewSwitcher
I tried calling delegate's method but in log nothing is printed.
[viewSwitcher loadSecondView];
}
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
// Setting the delegate
viewSwitcher.delegate = self;
return self;
}
- (void)viewDidLoad
{
NSString *urlStr = [[NSBundle mainBundle] pathForResource:#"bumper.mp4" ofType:nil];
NSURL *url = [NSURL fileURLWithPath:urlStr];
videoController = [[MPMoviePlayerController alloc] initWithContentURL:url];
videoController.controlStyle = MPMovieControlStyleNone;
[self.view addSubview:videoController.view];
videoController.view.frame = CGRectMake(0, 0, 480, 320);
videoController.fullscreen = YES;
// Remove the status bar from this view.
[[UIApplication sharedApplication] setStatusBarHidden:YES animated:UIStatusBarAnimationFade];
// TODO: This observer needs to be removed.
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(playbackStateChange:)
name:MPMoviePlayerPlaybackDidFinishNotification
object:videoController];
// Play the video.
[videoController play];
[super viewDidLoad];
}
// Receives notification once movie is finished.
-(void)playbackStateChange:(NSNotification*)notification
{
// TODO: Switch the view.
NSLog(#"Notification = %#", notification);
[self notifyViewSwitcher];
}
Here is the LOG:-
2011-08-03 02:44:47.333 My Video Player[24016:207] Notification = NSConcreteNotification 0x5768280 {name = MPMoviePlayerPlaybackDidFinishNotification; object = <MPMoviePlayerController: 0x5740940>; userInfo = {
MPMoviePlayerPlaybackDidFinishReasonUserInfoKey = 0;
}}
2011-08-03 02:44:47.337 My Video Player[24016:207] notifyViewSwitcher called.