I'm creating a UIPopoverController and setting "Editor1" as the content view controller.
When the caller receives the didDismissPopover I'm releasing the UIPopoverController.
This is the code:
- (IBAction)open1:(id)sender {
Editor1 *editor = [[Editor1 alloc] initWithNibName:#"Editor1" bundle:nil];
_popoverController = [[UIPopoverController alloc] initWithContentViewController:editor];
_popoverController.delegate = self;
[editor release];
[self.popOverController presentPopoverFromRect:self.open1Button.bounds inView:self.open1Button permittedArrowDirections:UIPopoverArrowDirectionAny animated:NO];
}
- (BOOL)popoverControllerShouldDismissPopover:(UIPopoverController *)popoverController{
NSLog(#"popoverControllerShouldDismissPopover");
return YES;
}
- (void)popoverControllerDidDismissPopover:(UIPopoverController *)popoverController{
NSLog(#"popvoerControllerDidDismissPopover");
[_popoverController release];
}
In my editor I have a UITextField where the user changes text and I save it when I get the message "editingDidEnd"
- (IBAction)editingDidEnd:(id)sender {
NSLog(#"Editing did End");
// SAVE PROCEDURE
}
My question regards the order in which the methods get called.
The order is:
2011-09-07 12:35:21.628 iosTest[1967:b603] popoverControllerShouldDismissPopover
2011-09-07 12:35:21.629 iosTest[1967:b603] popvoerControllerDidDismissPopover
2011-09-07 12:35:21.983 iosTest[1967:b603] Editing did End
2011-09-07 12:35:21.985 iosTest[1967:b603] viewWill Disappear
As you can see the popoverControllerDidDismissPopover gets called before editingDidEnd:, so this means I'm releasing the popover before I do my save procedure. This could bring me a crash problem.
Also, in my save procedure I need to ask the user for confirmation in some cases. I'm using a UIAlertView for this.
Do you have any recommendations?
Usually views are well-behaved and don't send events after they're off-screen. You can check for potential problems by enabling zombies (set the environment variable NSZombieEnabled=YES).
If there is a crash, the correct place to fix it is in -[Editor1 dealloc] (and possibly -viewDidUnload): just do textField.delegate = nil and you should stop receiving callbacks. This is not usually necessary except for web views and scroll views where it seems to be problematic (the scroll animation continues even if the VC is off-screen).
In your case, you can probably make saving happen in -popoverControllerShouldDismissPopover:, returning NO if you need to display a UIAlertView (and dismissing the popover when the button is pressed).
it seems, that _popoverController is the instance-property. in this case you can release it in viewDidUnload method of parent-controller.
Why don't you use UITextFieldDelegate protocol? Usage:
aTextField.delegate = self;
(...)
- (void)textFieldDidEndEditing:(UITextField *)textField {
NSLog(#"Editing did End");
// SAVE PROCEDURE
}
Read the documentation for more info.
Related
I have this piece of code to push a view controller:
// Setup the animation
[self.navigationController pushViewController:self.productView animated:YES];
self.productView.imageURL = [product imageURL];
// Set the title of the view to the product's name
self.productView.title = [product name];
// Set the label text of all the labels in the view
[self.productView.caloriesL setText:[product calories]];
[self.productView.fatL setText:[product fat]];
[self.productView.saturatesL setText:[product saturates]];
[self.productView.sugarL setText:[product sugar]];
[self.productView.fibreL setText:[product fibre]];
[self.productView.saltL setText:[product salt]];
But the delegate method viewDidAppear does not get called when the productView appears. I looked up the problem on google and theres a lot of different solutions, none of which I could apply to my problem.. I had a similar problem in a previous solution but I got around it by manually calling viewDidApear in the viewDidLoad method. Unfortunately in this case I can't do that as viewDidLoad is called only once (on the first push). Does anyone know how to fix this?
Thanks,
Jack Nutkins
EDIT:
Here is the viewDidAppear method in the productView (and selector):
- (void)viewDidAppear:(BOOL)animated{
//Start animating the activity indicator
[indicator startAnimating];
//Perform this method in background
[self performSelectorInBackground:#selector(loadImage) withObject:nil];
}
- (void) loadImage {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
// Load the animals image into a NSData boject and then assign it to the UIImageView
NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:imageURL]];
UIImage *image = [[UIImage alloc] initWithData:imageData];
self.imageView.image = image;
//Stop animating the activity indicator
[indicator stopAnimating];
[pool drain]; //see comment below
}
First: You definitely don't want to be calling any of the standard viewWillLoad, viewDidLoad, viewWillAppear, etc. methods manually. Let the OS do it for you.
Second: Can you show us how your viewDidAppear method is implemented in your self.productView instance? (Just a hunch, you're not expecting this method to be called on your navigation controller, right?) I just want to make sure your method signature is exactly correct. If it's not (due to a mispelling, improper args, etc.) then it definitely won't be called.
Third: I would move your pushViewController: call to after the rest of the code you provided. You don't want the view to be pushed on the screen (so the user can see it) and then have a bunch of on-screen values immediately change. Set your ivars and title property first, then push the view controller. This eliminates any weird flickering.
I solved it, though it doesn't seem conventional, can't believe I didn't try it earlier :
I put this line :
[self.productView viewDidAppear:YES];
Underneath :
// Setup the animation
[self.navigationController pushViewController:self.productView animated:YES];
I also moved the code to set the labels text to run before the above line. (As well as changing my code to send strings to the pushed controller rather that accessing its UI elements.)
Thanks for everyones help,
Jack
I'm trying to make a modal view which displays the champion of my app.
there's a NSMutableString variable called champ in modal view,
which is supposed to be updated by returnChamp function in main view.
the champ string is correctly set in main view,
but in modal view, the champ value appears as (null).
In fact, it seems it doesn't even go into the returnChamp function.
so apparently something wrong with my calling or implementing returnChamp,
but I have another function that does the similar, and that works fine.
could anyone please help me?
-(void) mainView{
.....
champ = [[currentPlayers objectAtIndex:playerIndex] retain];
NSLog(#"%#",champ);
modalWinner = [[winner alloc] init];
modalWinner.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self presentModalViewController:modalWinner animated:YES];
}
- (NSMutableString *) returnChamp{
NSLog(#"returnChamp");
return champ;
}
//in modalWinner
-(void) modalView{
..............
champName = [[NSMutableString alloc] init];
NSLog(#"%#", [(MainViewController *)self.parentViewController returnChamp]);
champName = [(MainViewController *)self.parentViewController returnChamp];
UIImage *champImage = [UIImage imageNamed:champName];
}
self.parentViewController is probably not actually a reference to your object. For some reason, it seems that the framework always insists on setting a UINavigationController as self.parentViewController - even for modals, and to the extent that it will create one if there isn't already one. This is probably going unnoticed because you're casting it to your MainViewController type.
You'll need to find a different way of making your original object available to be communicated with, or perhaps pass the appropriate value to the newly-instantiated controller before you present it.
For example, if you add a champName property to the modal class, you can do:
modalWinner = [[ModalWinnerViewController alloc] init];
modalWinner.champName = myValue; /* Set value before presenting controller */
[self presentModalViewController:modalWinner animated:YES];
There will probably be some code needed to update the UI with this value. The viewWillAppear method of the modal view controller is a good place for this as it is called by the framework immediately before the view is presented.
Note that this property-based approach could be used to keep a reference to your intended parent object, as well. And see here for a different approach to solving a similar problem.
I'm pretty new to the objective-c language (less than three months) but it is something that i really need to understand.
Suppose there is a controller (in a iOS environment) that manages a table view for input data from the user. The table must have editable cells and some features to make the value selection easier, for example a button that shows a popover with the possible values for a field.
Suppose there is a field to store country names. The popover first shows a list of continents; when the user selects a continent, the controller of the popover must show the countries of the previews selected continent.
Now, this popover appears in many places in the app so it will be nice if I can encapsulate it for later use. What i will expect for this popover is something like this:
...
#protocol MyPopoverDelegate<NSObject> {
-(void)didSelectCountry:(NSString *)countryName;
{
...
MyPopoverController *dataSelector = [[MyPopoverController] alloc] init];
dataSelector.dataType = CountryDataType;
dataSelector.delegate = self;
[dataSelector show];
[dataSelector release];
...
The problem here is the line [dataSelector release] because the code for managing the popover must stay alive until the country is selected. That's means the dataSelector variable must be a property of the caller class and that sucks.
The question then is:
How can i organize situations like this to have a reusable controller?
Thanks
Edited after vodkhang answer:
Ok, that's a good one, but dataSelector still is a property.
What if i do:
#implementation MyPopoverController
- (id)init {
...
[self retain];
...
}
- (void)popoverControllerDidDismissPopover: (UIPopoverController *)popoverController {
...
[delegate didFinishSelectingCountry:countryName];
[self release];
}
#end
I never see this behavior in objective-c, i feel that this is not the idea.
Why is it wrong?.
One of the way you can do for delegate method is to have:
MyPopOverDelegate
- (void)didFinishSelectingCountry:(NSString *)countryName popOver:(MyPopOver *)popOver;
Caller.m
// the caller
- (void)viewDidLoad {
MyPopoverController *dataSelector = [[MyPopoverController] alloc] init];
dataSelector.dataType = CountryDataType;
dataSelector.delegate = self;
[dataSelector show];
}
- (void)didFinishSelectingCountry:(NSString *)countryName popOver:(MyPopOver *)popOver {
// finish stuff
[popOver release];
}
This way is used a lot like NSUrlConnection, UIImagePickerController
If you want some unique object reusable across an entire app from anywhere in the view hierarchy, you can make it a property of the app delegate, and let the app delegate own it (retain it when live, release it during memory warnings, etc.).
A self retained object may eventually run into problems if you ever port your code to a garbage collected environment.
I'm trying to add a «loader-view» to my app which shows a spinner while doing stuff.
This works fine the first time, but it doesn't work a second time.
here's what I do:
I have a viewController for the spinner (spinnerViewController) and a nib-file which I made in IB (spinner.xib).
I load the nib in the viewDidLoad-event:
spinnerView = [[spinnerViewController alloc] initWithNibName:#"spinner" bundle:nil];
[spinnerView retain];
spinnerView is declared in the .h-file (spinnerViewController *spinnerView;)
next, I show the spinner-view:
[self.view addSubview:spinnerView.view];
[self.view bringSubviewToFront:spinnerView.view];
which works fine...
And now the trouble starts. No matter what I do, I can't show the spinner view again.
I tried just hiding it (self.view sendSubViewToBack: spinnerView.view) which works for hiding, but when I try to bring it to the front again (self.view bringSubViewToFront: spinnerView.view) it doesn't work.
I also tried removing the spinner-view and add it again with no success (within the spinnerViewController: [self.view removeFromSuperview] and to show it again [self.view addSubview... )
[EDIT]
I changed the whole setup a little and just made the spinner-view a subview in IB - again, hiding works, but showing again fails.
What I found out: After the bringSubViewToFront-command, I call some web-service to get some data. When I comment the following code out and just show the spinnerView, it works. So now I'm trying to figure out how to determine when the spinner-view appeared and then continue with the code - but naturally, this doesn't work (yet) :)
Any ideas what I'm doing wrong??? ;)
Problem solved.
This page gave the answer: http://urenjoy.blogspot.com/2009/05/uiactivityindicatorview.html
Apparently, the update has to happen in a separate thread, as the web-stuff blocks the current one, hence the view did not appear.
[NSThread detachNewThreadSelector:#selector(doWork) toTarget:self withObject:nil];
- (void) doWork {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
.....Time Consuming Code here .....
[pool release];
}
I might be not exactly on your question, but in general creating a ViewController class in order to show a spinner on the screen is a huge overkill ... just try to discover the logic behind what you do : you create a viewcontroller, but you never use it, you use the view.
So in short I believe you need only a UIView (the view property of the UIViewController)
Why don't you try something like :
... in your class interface...
UIActivityIndicator* activity;
... when the activity needs to happen ...
activity = [[UIActivityIndicator alloc] initWithActivityIndicatorStyle: ....
[activity startAnimating];
[self.view addSubview:activity];
[activity release]
... when the activity is finished
[activity removeFromSuperview]; //this will also decrease the retain count
I want to change an image on a view, from a popup dialog of 4-6 icons (imagine like changing your image on a messenger application).
The way I implement this modal popup is by creating a new view at IB, with opacity on the background, and then I load this as a subview:
IconsViewController *iconsViewController = [[IconsViewController alloc] initWithNibName:#"IconsView" bundle:nil];
[self.view addSubview:iconsViewController.view];
So, when the user touches an icon, I have
- (IBAction)iconIsSelected:(id)sender {
switch ([sender tag]) {
case 1:
[(ParentViewController*)[self superview] changeIcon];
break;
case 2:
// same here..
break;
default:
break;
}
[self.view removeFromSuperview];
[self release];
}
The changeIcon just sets the image to a corresponding icon.
As you can guess, this is not working - the changeIcon message never works.
I can't understand what am I doing wrong, any help much appreciated!
You have a few choices here...
First one is create a property on your IconsViewController of type ParentViewController*, for example:
#property (readwrite,nonatomic,assign) ParentViewController* parentController; // weak reference
To break this down further:
readwrite because we want to be able to access the value via [self parentController] but also change it via [iconsViewController setParentController:self]
nonatomic because I'm not too worried about threading
assign to make it a "weak reference" where the parent will not be retained by the child. If they each retain the other, it could lead to memory leaks later because unless explicitly released you'd end up with a retain circle causing neither object to hit a zero retain count.
When you load from nib, set the property:
IconsViewController *iconsViewController = [[IconsViewController alloc] initWithNibName:#"IconsView" bundle:nil];
iconsViewController.parentController = self;
Then, call to it from inside of iconIsSelected like this:
[[self parentController] changeIcon];
Alternatively, you can create a delegate protocol:
#protocol IconViewSelectedDelegate (NSObject)
- (void) changeIcon;
#end
And use that protocol as a property, instead of the parent view controller type. This is more abstract, but it keeps the design cleaner. The parent view controller would then implement that delegate protocol, as one of many others.
Another option is to use NSNotificationCenter and publish/subscribe to events from your dynamic view. This is the "loosest" coupling between the two objects, but it might be overkill for this scenario.
The superview of a view is a view, not a view controller, yet you cast the superview to be of class ParentViewController. If the view has no superview, it returns nil, and message to nil are no-ops (which explains why you don't crash there).
BTW, that [self release] at the end is highly suspicious.