How to pop a viewController and then Push a viewController through delegation - iphone

I have a UITableViewController that when a cell is pressed, I want the controller to pop itself, and then have the controller it pop's to, push another view controller onto the stack.
I am invoking this method because the popped-to viewController is the delegate of the tableViewController
I am currently invoking this method with a delay on it, because otherwise, everything gets screwed up waiting for the animation to end. Doing it this way seems a bit hacky and seems to me like it would fail if someone's device didn't pop the view in the allotted wait time I have given it.
Here is some of the code:
//**** code in my tableViewController ***//
[self.navigationController popViewControllerAnimated:YES];
[self.delegate cellPressedInTableViewControllerWithCalculationsModel:(id)anArgmentMyDelegateMethodTakes];
// **** Code in the viewController being popped to ****//
//CalculationsViewController is a subclass of UIViewController
CalculationsViewController *calcViewController = [[CalculationsViewController alloc] init];
//some customization code would go her
[self.navigationController performSelector:#selector(pushViewController:animated:) withObject:calcViewController afterDelay:0.75];
//this seems like the arbitrary part, the 0.75 second delay.
[calcViewController release];
There seems like there should be a better way to pop/push through delegation that will execute after the animation finishes. The wait time seems to me like it could cause unexpected problems.
I have also tried using:
performSelectorOnMainThread:withObject:waitUntilDone
But the code just executes immediately and the view hierarchy screwed up.
I have also looked at this question:
Delegation question
and it has gotten me this far, but I am curious to see if there is a better way to perform such a task,
Thanks.
edit: I have also tried wrapping the method in an instance of NSInvocation, and I couldn't get it to coordinate the method call until after the animation finished without arbitrarily setting the delay

The cleanest way to do more than a single push or pop of a view controller is to set the UINavigationControllers view controllers array.
For example, to pop and then push a view controller:
MyTableViewController *vc = [[MyTableViewController alloc] init];
NSMutableArray *controllers = [NSMutableArray arrayWithArray:self.navigationController.viewControllers];
[controllers removeLastObject];
[controllers addObject:vc];
[self.navigationController setViewControllers:controllers animated:YES];

You should use a flag to overcome this situation. You set this flag in viewWillDisappear method of view controller being popped. When this flag is set then and then you can push another view controller on stack. Hope it's clear.

How about when you dismiss your UIViewController containing the table you send a NSNotifcation in your viewDidDisappear method like so:
- (void)viewDidDisappear:(BOOL)animated
{
[[NSNotificationCenter defaultCenter] postNotificationName:#"loadOtherVC" object:nil];
}
And in your parent view controller that will push a new view controller, you add an observer for that notification like so:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(LoadOtherVC:) name:#"loadOtherVC" object:nil];
You should have a method that matches the selector.
- (void) LoadOtherVC:(NSNotification *) notification
{
// load your other view controller you want here
}

Don't pop it from the top level controller. Call the delegate method that will pop the view off the navigation controller and then push a new one on.

I liked Alexandre's solution but if I were a delegate person, I wouldn't want to use notification. So in that case, we can just use the delegate in the viewDidDisappear method.
So, in the didSelectRowAtIndexPath method, you can pop the controller-
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
[self.navigationController popViewControllerAnimated:YES];
}
and in the same View Controller, the ViewController you are popping, call the delegate method in the viewDidDisappear method like-
-(void)viewDidDisappear:(BOOL)animated{
[self.delegate cellPressedInTableViewControllerWithCalculationsModel:(id)anArgmentMyDelegateMethodTakes];
}
Then in the controller that is pushed can implement the delegate method and inside that delegate method, you can do whatever you want.

Related

Dismiss two modal (table)view controllers

I know there's like 3-5 similar questions here, but non of the answers solves my problem.
I have a ViewController that opens a modal (table)view controller, which opens another one. Both modal view controllers are in fact table view controllers. I'm trying to dismiss both of them from the second one. I tried every accepted answer on similar question, none of them worked for me.
I tried
[self dismissModalViewControllerAnimated:true]
[self.parentViewController dismissModalViewControllerAnimated:true]
[self.parentViewController.parentViewController dismissModalViewControllerAnimated:true]
[self.presentingViewController dismissModalViewControllerAnimated:true]
[self.presentingViewController.presentingViewController dismissModalViewControllerAnimated:true]
When I try options 2, 3 and 5, nothing happens at all. When I use options 1, and 4, I see dismiss modal view animation and the underlying view itself for a moment, and then everything goes back to the second modal view (this time without animation).
I'm starting to think that this have something with the fact that I use tableViewControllers for modal views.
Btw, I'm dismissing modal views in didSelectRowAtIndexPath.
Try this:-
When you dismiss your SecondView set a BOOL flag variable in app delegate file and check that variable in your FirstView's viewWillAppear method whether SecondView was open and close or not. If so, then [self dismissModalViewControllerAnimated:true]
typical model view controller behavior would suggest that you dismiss the modal view controller from the calling view controller rather than from self. not a hard and fast rule, but good practice.
to accomplish this, create a protocol:
#protocol MyModalViewControllerDelegate
- (void)modalViewControllerDidFinish;
#end
and make both the parentViewController and FirstModalViewController be implemntors of this protocol.
#interface FirstModalViewController <MyModalViewControllerDelegate>
then in both FirstModalViewController.h and SecondModalViewController.h, add:
#property id<MyModalViewControllerDelegate> modalViewControllerDelegate
in both parentViewController and FirstModalViewController, right before calling presentModalViewController:... , set the following:
modalViewControllerAboutToAppear.modalViewControllerDelegate = self;
[self presentModalViewController:modalViewControllerAboutToAppear animated:YES];
next, in the SecondModalViewController, in the code where you determine that the item needs to be dismissed, call
[self.modalViewControllerDelegate modalViewControllerDidFinish];
now, in FirstModalViewController, implement the following:
- (void)modalViewControllerDidFinish:(MyModalViewController*)controller {
[self dismissModalViewControllerAnimated:YES]
[self.modalViewControllerDelegate modalViewControllerDidFinish];
}
and finally, in the parent view controller, you should be able to perform:
- (void)modalViewControllerDidFinish:(MyModalViewController*)controller {
[self dismissModalViewControllerAnimated:YES]
}
Since I don't use delegate files, I did the following:
To FirstView add field
BOOL mClose;
To FirstView add method
- (void)close
{
mClose = YES;
}
To FirstView method viewDidAppear add
if (mClose)
{
[self dismissModalViewControllerAnimated:YES];
}
To FirstView method which opens SecondView add
[secondView closeWhenDone:self];
To SecondView add field
FirstView *mParent;
To SecondView add method
- (void)closeWhenDone:(FirstView*)parent
{
mParent = parent;
}
To SecondView method which closes it add
[mParent close];

what's called after returning from presentModalViewController / dismissModalViewControllerAnimated:

to show a modal uiview out of my mainView I use:
[self presentModalViewController:myController animated:YES];
and in MyController I close that view with:
[self dismissModalViewControllerAnimated:YES];
But how can I know in the mainView that the modal was finished (to redraw my table)?
Currently I set a local variable to YES in my mainView after starting the modal view an react on viewWillAppear:
[self presentModalViewController:myController animated:YES];
_reloadTableData = YES;
-(void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
if (_reloadTableData) {
_reloadTableData = NO;
[_tableView reloadData];
}
}
Is there a better way to do so ?
Generally speaking, it's not appropriate to dismiss the modal view by the modal view itself.
Instead, you should set your main view as the delegate of the modal view. When you modal view finishes its task, it can let its delegate know and let its delegate dismiss it. This is the very common so-called delegate design pattern in Objective-C.
btw, you may want to consult with some code samples to gain a better understanding of this delegate pattern. I suggest you take a look at one of Xcode's default templates - the Utility Application template. It has a very succinct and simple and straightforward delegate structure built inside.

iPhone, need the IF for dismissModalViewControllerAnimated ELSE removeFromSuperview?

I need to add this to my dismiss button :-
[self dismissModalViewControllerAnimated:YES];
[self release];
else
[self.view removeFromSuperview];
I thought
if( self.navigationController.modalViewController ) {
would work be it nevers true
A couple of things:
1) You shouldn't ever release yourself in an object. If you're presenting a modal view controller, you should perform the release there since the view controller will now be retained by the view controller's .modalViewController property:
(In the parent):
UIViewController *someViewController = [[UIViewController alloc] init];
[self presentModalViewController:someViewController animated:YES];
[someViewController release];
2) The parent will store its child modal view controller in .modalViewController. The child will have its .parentViewController property set in this case. If the view has been added as a subview, its .superview property will be set. These are not mutually exclusive, however, so be careful. Generally speaking, UIViewControllers are intended to host full-screen views, and if you're adding the view as a subview, you should ask yourself if the view should just be a UIView subclass, and move the logic into the parent view controller.
That said, I suppose you could check your case (assuming you don't present modal view controller and add as a subview simultaneously):
if (self.parentViewController) {
[self dismissModalViewControllerAnimated:YES];
} else if (self.view.superview) {
[self.view removeFromSuperview]
}
In the latter superview case, the view controller will still be hanging around, so you'd need to let the other view controller know via delegate method or something to release you. In the first case, if you have released the presented view controller already as I described above, it will be released automatically when the parent view controller sets its .modalViewController property to nil.
Normally for a "dismiss" button I would call a method in the controller that presented the modal controller (use a delegate), not try to dismiss the modal view controller from within itself. I don't quite get what youre trying to do though, but that [self release] looks bad. I don't think you ever want to release self like that.
Try this in you modal viewcontroller:
- (IBAction)close:(id)sender {
[self.parentViewController dismissModalViewControllerAnimated:YES];
}
Then just connect the button's action to that method.

How do be notified when a ViewController is removed from a NavigationController

Is there a way to be notified when a ViewController is removed from a UINavigationController because the back button was pressed?
You can use viewWillDisappear: in the view controller that is disappearing. If the other view controller needs to be notified, you can use a delegate method to notify it:
//in the disappearing view controller, class MYViewController
-(void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
//do stuff you need to do
if ([self.delegate respondsToSelector:#selector(myViewControllerDidDisappear:)])
[self.delegate myViewControllerDidDisappear:self]; //bottom view controller is delegate
}
In conjunction with eman's method, check
[navController.viewcontrollers count]
If it is one greater than before (you need to maintain a count) then something was pushed. If it is one less, and viewWillDisappear: was called, then the view controller was removed.

Can presentModalViewController work at startup?

I'd like to use a modal UITableView at startup to ask users for password, etc. if they are not already configured. However, the command to call the uitableview doesn't seem to work inside viewDidLoad.
startup code:
- (void)viewDidLoad {
rootViewController = [[SettingsController alloc]
initWithStyle:UITableViewStyleGrouped];
navigationController = [[UINavigationController alloc]
initWithRootViewController:rootViewController];
// place where code doesn't work
//[self presentModalViewController:navigationController animated:YES];
}
However, the same code works fine when called later by a button:
- (IBAction)settingsPressed:(id)sender{
[self presentModalViewController:navigationController animated:YES];
}
Related question: how do I sense (at the upper level) when the UITableView has used the command to quit?
[self.parentViewController dismissModalViewControllerAnimated:YES];
You can place the presentModalViewController:animated: call elsewhere in code - it should work in the viewWillAppear method of the view controller, or in the applicationDidFinishLaunching method in the app delegate (this is where I place my on-launch modal controllers).
As for knowing when the view controller disappears, you can define a method on the parent view controller and override the implementation of dismissModalViewControllerAnimated on the child controller to call the method. Something like this:
// Parent view controller, of class ParentController
- (void)modalViewControllerWasDismissed {
NSLog(#"dismissed!");
}
// Modal (child) view controller
- (void)dismissModalViewControllerAnimated:(BOOL)animated {
ParentController *parent = (ParentController *)(self.parentViewController);
[parent modalViewControllerWasDismissed];
[super dismissModalViewControllerAnimated:animated];
}
I had quite the same problem. I know the topic is old but maybe my solution could help someone else...
You just have to move your modal definition in a method:
// ModalViewController initialization
- (void) presentStartUpModal
{
ModalStartupViewController *startUpModal = [[ModalStartupViewController alloc] initWithNibName:#"StartUpModalView" bundle:nil];
startUpModal.delegate = self;
[self presentModalViewController:startUpModal animated:YES];
[startUpModal release];
}
Next, in viewDidLoad, call your modal definition method in a performSelector:withObject:afterDelay: with 0 as delay value. Like this:
- (void)viewDidLoad
{
[super viewDidLoad];
//[self presentStartUpModal]; // <== This line don't seems to work but the next one is fine.
[self performSelector:#selector(presentStartUpModal) withObject:nil afterDelay:0.0];
}
I still don't understand why the 'standard' way doesn't work.
If you are going to do it like that then you are going to have to declare your own protocol to be able to tell when the UITableView dismissed the parentViewController, so you declare a protocol that has a method like
-(void)MyTableViewDidDismiss
then in your parent class you can implement this protocol and after you dismissModalView in tableView you can call MyTableViewDidDismiss on the delegate (whihc is the parent view controller).