So, I am trying to implement a swipe right to go back to the previous view controller feature.
But when I have the following code in my current view controller, I get a black screen
- (void)initPreviousViewController:(GGMainViewController *)previous
{
self.previousViewController = previous;
self.previousViewController.view.frame = self.currentView.bounds; //self.currentView is declared elsewhere (in the init of the current view controller)
[self addChildViewController:self.previousViewController];
[self.currentView addSubview:self.previousViewController.view];
[self.previousViewController didMoveToParentViewController:self];
{
^I call this method within the previous view controller after initializing the current view controller, and before pushing the current view controller
If I change self.previousViewController = previous; to self.previousViewController = [GGMainViewController alloc] init]; it works. However, I don't want to reinitialize the previous controller.
So how do I set the previous view controller as a property of the current view controller.
Oh, I am also an iOS first timer, so if this is not something that is recommended, please let me know.
Rationale behind my thinking:
Normally the user would just click a button, and the UINavigationController would do the trick, but since I am using a swipe functionality, I think the user needs to see the previous view controller behind the current view controller as they swipe the screen.
As requested
How I call the currentViewController from the previousViewController
- (void)displayCurrentViewController:(id)sender
{
GGNextViewController *next = [[GGNextViewController alloc] init];
[next initializeExploreViewController:self]; // If I comment this out, everything is ok (screen is not black,etc. apart from being able to swipe backwards
[self.navigationController pushViewController:next animated:YES];
}
Your using the self.navigationController for pushing the current view controller, So you can call a method when ever the right swipe gesture fired.
Try this code in your Current view controller(GGNextViewController.m)...
1. Add the rightSwipeGestureAction() selector to the gesture recognizer which you have.
2.
-(void)rightSwipeGestureAction
{
[self.navigationController popViewControllerAnimated:YES];
}
It turns out that the following lines were causing the problem. I just decided to comment them out and then it worked, without a black screen.
[self addChildViewController:self.previousViewController];
[self.previousViewController didMoveToParentViewController:self];
I can't just pop it with the navigation controller, because I want to create somewhat of a dragging effect, the user swipes (as they see the previous view controller below) until halfway through the screen, from where it goes to the previous view controller.
Related
I have added following piece of code in a view.
- (IBAction)accept_clicked:(id)sender {
[self.view removeFromSuperview];
self.view = nil;
}
Once accept is clicked, I have removed the own view like this. It worked fine, anyhow is it fine to do like this or It should be removed from another view(parent)?
Don't do this (with self.view) - it doesn't looks good and you might face difficult to find problems. self.view is the main view associated with an UIViewController. So this view to be visible on the screen, you must have shown it somehow: either pushing it to a UINavigationController or presenting it modally with -presentViewController:animated:completion: (IOS5+) or - presentModalViewController:animated:. Showing a view by instantiating a view controller and adding its view to the current view controller's view is not a good practice also:
//Not good
MyViewController *mvc = [[MyViewController alloc] init];
[self.view addSubView:mvc.view];
In your particular case I suppose you are showing some terms and conditions (or something similar) and have an accept and deny button, your best solution would be to present your view controller from somewhere, implement a delegate method, so the presenting view controller can have the result and then in your -accept_clicked: method to use either [self dismissModalViewControllerAnimated:YES] or [self dismissViewControllerAnimated:completion:] (IOS5+),
I need to go to the first view in my app. I have a few views pushed onto the stack then a modal navigation controller and more views pushed onto that.
The problem I'm having is that using [[self navigationController] popToRootViewControllerAnimated:YES]; only goes back to the first view in the modal stack.
And I can't get [[self navigationController] popToViewController:.. to work because the true first view controller isn't accesible with [[self navigationController] viewControllers].
Any ideas on how to accomplish this? Thanks.
Do this:
[[self navigationController] dismissModalViewControllerAnimated:YES];
That will get you back to the VC that modally presented the navigation controller. Getting farther back after that depend on how you pushed those "few views" before the navigation controller.
Edit - explanation to get to the deepest root...
It sounds like those "few views" are on another, underlying navigation controller's stack. This can be a little tricky, because the clean way to get farther back in that stack is to have that underlying navigation controller pop to it's own root. But how can it know that the modal VC on top of it is done?
Let's call the view controller that did the modal presentation of second navigation controller VC_a. It's a modally presented navigation controller whose topmost VC is VC_b. How can VC_a know to pop to it's navigation root when VC_b modally dismisses itself?
The good answer (usually) is that VC_b decided to dismiss itself for a reason - some condition in your app/model changed to make it decide to be done.
We want VC_a to detect this condition, too. When VC_b gets dismissed, and VC_a gets a viewWillAppear message because it's about to be uncovered:
// VC_a.m
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
if (/* some app condition that's true when VC_b is done */) {
// I must be appearing because VC_b is done, and I'm being uncovered
// That means I'm done, too. So pop...
[self.navigationController popToRootViewControllerAnimated:NO];
} else {
// I must be appearing for the normal reason, because I was just pushed onto the stack
}
}
You need to do it by using the delegation pattern. Specifically, by creating a protocol that implements the delegate's respondsToSelector method.
See this post for complete details. It should be almost exactly what you are looking for. I had to do something similar, except I only needed to pop one view off the navigation stack instead of using popToRootViewControllerAnimated:.
For iOS6...
[self.view.window.rootViewController dismissViewControllerAnimated:YES completion:nil];
In AppDelegate.m class create method with bellow flow...
-(void)MethodName{//your method name
YourViewController *objViewController = [[[YourViewController alloc] initWithNibName:#"YourViewController" bundle:nil] autorelease]; ///define your viewcontroller name like "FirstViewController"
UINavigationController *yourNavigationController = [[[UINavigationController alloc] initWithRootViewController:objViewController] autorelease];
self.window.rootViewController = yourNavigationController;
}
When you want redirect on firstview just call this method from appdelegate object....
I have a Navigation Controller that is presented modally with 4 views in the stack. The final view has a done button that dismisses the modal view. When I then present the modal view again, it automatically goes to that last view instead of the first one. I added a line to pop to first view after dismissed but it adds a weird animation whether I set it to YES or NO. Maybe I'm doing it wrong?
- (void)dismissModalView
{
[self dismissModalViewControllerAnimated:YES];
[self.navigationController popToViewController:[self.navigationController.viewControllers objectAtIndex:([self.navigationController.viewControllers count] -4)] animated:YES];
}
Update:
This is the method used to present the modal view/navcontroller
- (void)showModalView
{
self.optionsNavController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self.navigationController presentModalViewController:self.optionsNavController animated:YES];
}
No, it looks right. If you want to retain the state of the Navigation controller then don't present it modally as it will get deallocated when you dismiss the view.
Modal views are usually used to present information that only needs to be shown briefly without maintaining the state of the view (i.e. about page, login page, settings page, etc).
Excuse me if I'm oversimplifying your issue, but if your need is to pop straight back to the first view controller, perhaps you could give the popToRootViewControllerAnimated: method a try instead of popToViewController:.
I'm not sure what the problem with the dismiss code you posted is, but the following should work:
- (void)showModalView
{
self.optionsNavController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self.optionsNavController popToRootViewControllerAnimated:NO];
[self.navigationController presentModalViewController:self.optionsNavController animated:YES];
}
Also, viewDidLoad is intended to only be called once every time the view is loaded, viewWillAppear a
So I have a stack of three UITableViewControllers, each of which displays its view correctly underneath the navigation bar when I tap through the UI manually.
However, now I'm working on restoring state across app restart, and so I'm pushing the same two controllers on top of the root view controller, one at a time, in the same method in the main thread. What ends up happening then is that the middle controller's view is laid out too far down, and the top controller's view is too far up (underneath the nav bar).
Relevant code:
for (int i = 0; i < [controllerState count]-1; i++) {
MyViewController* top = (MyViewController*)navigationController.topViewController;
int key = [[controllerState objectAtIndex:i] integerValue];
[top restoreNextViewController:key]; // this calls pushViewController:
// so top will be different in the next iteration
}
I suspect that the problem is that I'm not allowing some important UI refresh process to take place in between the two pushes, because they happen in the same thread. It almost looks as though the automatic view adjustment that's supposed to affect the top controller affects the middle one instead.
Is that right? And if so, what should I do, since I do want all the state-restoration to take place immediately upon app start?
EDIT: looks like I was unclear. restoreNextViewController: is a MyViewController subclass method that restores the controller's state based on a stored key, and then pushes the appropriate child controller with [self.navigationController pushViewController:foo animated:NO]. I'm doing this because my actual app, unlike this simplified case, has up to 6 controllers in the stack, and they're not always the same ones. So I figured this would be a cleaner design than going down the stack checking controllers' classes. Each controller already knows how to push a child controller in response to user input; why not reuse that on app restart?
I'm not having any trouble getting the controllers to show up; they're just being laid out strangely.
Have you considered having each view controller push its child during viewWillAppear:? I would just set an isRestoringState property in your appDelegate and check that during viewWillAppear:, if it's set, run your restore for that view, including pushing any visible child view. Something like:
- (void)viewWillAppear:(BOOL)animated {
if ([[UIApplication sharedApplication] isRestoringState]) {
// restore local state, set myChildController if a child is visible
if (myChildController) {
[self.navigationController pushViewController:myChildController animated:NO];
}
}
}
You can call pushViewController:animated: multiple times. Please post the code for -restoreNextViewController. It's confusing why this code is as complex as it is. Have you read the section of the View Controller Guide on Creating a Nav Controller? They cover pushing view controllers on the stack at startup.
I agree with Rob, I would look at implementing UINavigationController when your application is loaded. Then you would push each of your controllers onto UINavigtionController in the sequence you want them layered.
- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
So if you know what state you want to bring your application back to you could load the appropriate ViewController in the series to be latered and push them onto the NavigationController.
UIViewController *myViewController = [[UIViewController alloc] initWithNibName:#"myView" bundle:nil];
[navigationController pushViewController:myViewController animated:NO];
Then if you want to "pop" back to the UIViewController either the user can press the "Back" button on navigationbar for free. Or you can control the navigation with
- (UIViewController *)popViewControllerAnimated:(BOOL)animated
eg [[self navigationController] popViewControllerAnimated:NO];
You can also control whether you want the NavigationBar to show or not if you want to control the push/pop yourself. I hope I've explained this well enough I've just traveled this road recently myself.
I ended up manually resetting each table view's content inset during its controller's viewWillAppear:.
I have a viewController (Planner) that loads two view controllers (InfoEditor and MonthlyPlan) when the application starts. MonthlyPlan is hidden behind InfoEditor (on load).
So my question is when I exchange InfoEditor for MonthlyPlan (MonthlyPlan gets brought to the top) how can I have data on the MonthlyPlan view be updated. An NSLog in viewDidLoad is being called when the application starts (which makes sense.) NSLogs in viewDidAppear and viewWillAppear aren't doing anything.
Any ideas?
Thanks!
-- Adding more details --
I'm creating the view hierarchy myself. A simple viewController that is just loading two other viewControllers. The two child viewControllers are loaded at the same time (on launch of application.) To exchange the two views I'm using this code:
[self.view exchangeSubviewAtIndex:1 withSubviewAtIndex:0];
The exchanging of the views is fine. The part that is missing is just some way of telling the subview, you're in front, update some properties.
There's a lack of details here. How are you "exchanging" the two views?
If you were using a UINavigationController as the container then viewWillAppear/viewDidAppear would be called whenever you push/pop a new viewController. These calls are made by the UINavigationController itself. If you ARE using a UINavigationController then make sure you have the prototypes correct for these functions.
- (void)viewWillAppear:(BOOL)animated
If you are trying to implement a view hierarchy yourself then you may need to make these calls yourself as part of activating/deactivating the views. From the SDK page of viewWillAppear;
If the view belonging to a view
controller is added to a view
hierarchy directly, the view
controller will not receive this
message. If you insert or add a view
to the view hierarchy, and it has a
view controller, you should send the
associated view controller this
message directly.
Update:
With the new details the problem is clear: This is a situation where you must send the disappear/appear messages yourself as suggested by the SDK. These functions are not called automagically when views are directly inserted/removed/changed, they are used by higher-level code (such as UINavigationController) that provides hierarchy support.
If you think about your example of using exchangeSubView then nothing is disappearing, one view just happens to cover the other wholly or partially depending on their regions and opacity.
I would suggest that if you wish to swap views then you really do remove/add as needed, and manually send the viewWillAppear / viewWillDisappear notifications to their controllers.
E.g.
// your top level view controller
-(void) switchActiveView:(UIViewController*)controller animated:(BOOL)animated
{
UIController* removedController = nil;
// tell the current controller it'll disappear and remove it
if (currentController)
{
[currentController viewWillDisapear:animated];
[currentController.view removeFromSuperView];
removedController = currentController;
}
// tell the new controller it'll appear and add its view
if (controller)
{
[controller viewWillAppear:animated];
[self.view addSubView:controller.view];
currentController = [controller retain];
}
// now tell them they did disappear/appear
[removedController viewDidDisappear: animated];
[currentController viewDidAppear: animated];
[removedController release];
}
I would just add an updataData method to each subview and call it at the same time you bring it to the front. You would need to add a variable to your root view controller to track the active subView:
[self.view exchangeSubviewAtIndex:1 withSubviewAtIndex:0];
if (subView1IsActive) [subView1Controller updateData];
else [subView2Controller updateData];