I have a parent class with tableview and searchbar over it which is a subclass of tableview controller. Delegates for the searchBar and searchdisplaycontroller are set in a seperate class inherited from UISearchdisplaycontroller. The datasource and delegates for tableview and searchbar are handled in this class seperately. The classes are under ARC.
Hence, When a user taps on search, the control transfers from FilesListController (parent)class to this class. Now, When a user taps on cancel button, the searchbar delegate set in this class i.e.
- (void)searchBarCancelButtonClicked:(UISearchBar *) searchBar
is CALLED but DOESN'T serve the purpose of dismissing the full screen searchtableview and return to the parentviewcontroller. However, if I don't write this delegate in the search class, it works properly. I have set the searchbar delegates in xib and on calling:
- (BOOL)searchBarShouldBeginEditing:(UISearchBar *)searchBar
like this:
self.searchResultsTableView.delegate = self;
self.searchResultsTableView.dataSource = self;
[parentFileViewController.searchDisplayController setDelegate:self];
Where am I going wrong? Thanks in advance.
If you want to dismiss a UISearchBar with a SearchBarController, just use this Code:
[self.searchDisplayController setActive:NO animated:YES];
you should implement resign the responder in the delegate function i.e
- (void)searchBarCancelButtonClicked:(UISearchBar *) searchBar {
[searchBar resignFirstResponder];
}
Memory warnings can appear at any time during the application run time, you must assume a memory warning will happen and the view and disposable objects will have to be recreated.
We are handling such situation by setting to nil our arrays:
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
if([self isViewLoaded] && self.view.window == nil)
{
self.view = nil;
keys = nil;
names = nil;
errorDuringNetworkCall = nil;
}
}
And by dismissing the search bar tableview before performing the segue operation:
[self performSegueWithIdentifier:#"navigateToNextScreen" sender:self];
self.searchBar.text = #"";
[self.searchDisplayController setActive:NO animated:YES];
After a Memory warning is received the viewDidLoad method is called again and the arrays are populated, the search bar will continue to be useful.work without issues
Related
I've got two UIViewControllers. I'm using modal segue to the second one, when coming back I use dismissViewControllerAnimated. I want to fire a method when I come back to the first one. How can I do that?
I tried to fire a custom notification before dismissViewControllerAnimated and catching it in the first UIViewController, but it doesn't catch anything, because it's still on the second one when it's fired.
There are easy options I can see.
Use the viewDidDisappear: method in the view you're dismissing.
dismissViewControllerAnimated:completion: method accepts a block that actually executes after viewDidDisappear executes in the dismissing view.
To pass a reference from one view controller to the next:
In the second view controller's .h file, add a property:
#property (nonatomic,strong) FirstViewController *firstVC;
In your first view controller, add the following method:
- (void)prepareForSegue:(UIStoryboardSegue*)segue sender:(id)sender {
if([#"segue_YOUR_SEGUE_NAME" isEqualToString:[segue identifier]]) {
if([[segue destinationViewController] isKindOfClass:
[SecondViewController class]]) {
SecondViewController *dest = (SecondViewController*)[segue
destinationViewController];
dest.firstVC = self;
}
}
}
Now, in your second view controller, you can do two things, as I already stated:
[self dismissViewControllerAnimated:YES
completion:^{
[self.firstVC someMethod];
}];
OR...
- (void)viewDidDisappear:(BOOL)animated {
[super viewDidDisappear:animated];
[self.firstVC someMethod];
}
I have an app with a tab bar controller (2 tabs). In one tab view controller, a button leads to an alert window. I want one button of the alert window to call a table view containing possible answers. I want that table view to have a done button and a title. I think that means a navigation controller has to be used. But most everything I can find on navigation controllers assumes a much more complicated situation. Here's part of the alert window logic:
-(void) alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
if (buttonIndex == 2) {
AnswersViewController *aVC = [[AnswersViewController alloc] init];
[self presentViewController:aVC
animated:YES
completion:NULL];
}
}
And AnswersViewController looks like this:
#interface AnswersViewController : UITableViewController
#end
#implementation AnswersViewController
- (id) init
{
self = [super initWithStyle:UITableViewStylePlain];
return self;
}
- (id) initWithStyle:(UITableViewStyle)style
{
return [self init];
}
- (void)viewDidLoad
{
[super viewDidLoad];
[[self view] setBackgroundColor:[UIColor redColor]];
}
#end
This code all works as expected (an empty red UITableView appears).
Two questions I guess: 1. Is there a simple modification to what I have that can give me a done button and title in my table view? 2. If I have to go to a navigation controller (probably), how can I make a bare-bones navigation controller with a done button and title and embed the table view within it? Oh, and I want to do this programatically. And I think I prefer the done button and title to be in the navigation bar, no tool bar desired. Thanks!
To get what you are looking for, you do need to use a UINavigationController. That will provide the UINavigationBar where you can display a title and also buttons.
To implement this with a UINavigationController, you want to do smoothing like this (assuming you are using ARC, so you don't need to worry about memory management):
-(void) alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
if (buttonIndex == 2) {
AnswersViewController *aVC = [[AnswersViewController alloc] init];
//Make our done button
//Target is this same class, tapping the button will call dismissAnswersViewController:
aVC.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:#selector(dismissAnswersViewController:)];
//Set the title of the view controller
aVC.title = #"Answers";
UINavigationController *aNavigationController = [[UINavigationController alloc] initWithRootViewController:aVC];
[self presentViewController:aNavigationController
animated:YES
completion:NULL];
}
}
Then you would also implement - (void)dismissAnswersViewController:(id)sender in the same class as the UIAlertView delegate method (based on the implementation I have here).
Hope this helps!
I have a weird problem where a UIPopovercontroller is immediately deallocating its content view controller after loading the popover, and then reinitializing it.
My goal is to read a textField when the popover is being dismissed.
My impression was that I create a UIViewController and set it as the content view controller for the popover. The PopoverViewController will then retain the content view controller and I can (auto)release it.
Later, when the popover is being dismissed, it will release the popover (and with it the content view controller). But that's not working. This is my relevant code:
- (IBAction)popoverButton:(id)sender {
// Create & Initialize content view controller
ContentViewController* cvc = [[[ContentViewController alloc] initWithNibName:#"ContentViewController" bundle:nil] autorelease];
// Create, initialize and load popover
popoverController = [[UIPopoverController alloc] initWithContentViewController:cvc];
[popoverController setDelegate:self];
[popoverController presentPopoverFromBarButtonItem:sender permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
NSLog(#"popoverButton: %#, retainCount: %d", cvc, [cvc retainCount]);
}
- (BOOL)popoverControllerShouldDismissPopover:(UIPopoverController *)senderPopoverController
{
NSLog(#"popover should dismiss");
ContentViewController *dvc = (ContentViewController *)([popoverController contentViewController]);
NSLog(#"%# %# %#", dvc, [dvc testTextfield], [[[dvc testTextfield] text] description]);
return YES;
}
ContentViewController.m
- (void)viewDidLoad
{
[super viewDidLoad];
[[self testTextfield] setText:#"Bla"];
NSLog(#"viewDidLoad: %#", testTextfield);
}
- (void)dealloc {
NSLog(#"dealloc: %#", testTextfield);
[testTextfield release];
[super dealloc];
}
When I open the popover, the Log would be (I think the order of the output does not represent the order when it is actually called):
Popover Test[2363:707] viewDidLoad: <UITextField: 0x185750; ...>
Popover Test[2363:707] viewDidLoad: (null)
Popover Test[2363:707] popoverButton: <ContentViewController: 0x1844e0>, retainCount: 4
Popover Test[2363:707] dealloc: <UITextField: 0x185750; ...>
And when I dismiss it:
Popover Test[2363:707] popover should dismiss
Popover Test[2363:707] <ContentViewController: 0x1844e0> (null) (null)
Popover Test[2363:707] popover did dismiss
Popover Test[2363:707] <UIPopoverController: 0x184860>
Popover Test[2363:707] dealloc: (null)
So my questions would be:
Why is the ContentViewController deallocated and initialized a second time?
Why do the outlets (textField) not work anymore when its loaded the second time?
If I could solve this, I would be able to read from the textField in popoverControllershouldDismissPopover
Since ContentViewController is your class, implement the appropriate init* method (if you haven't already), set a break point and the debugger will stop on it at each allocation, answering your question as to why it is being recreated.
Note that retainCount is useless; don't call it.
Ah -- OK -- so, you are creating one instance when you are loading the nib file and a second instance directly in your code. Instead, you want an outlet somewhere that is connected to the instance in the nib file.
As for retainCount; Calling -retainCount Considered Harmful and When to use -retainCount?
I use the method performSegueWithIdentifier:sender: to open a new ViewController from a storyboard-file programmatically. This works like a charm.
But on every time when this method is being called, a new ViewController would be created. Is it possible to use the existing ViewController, if it exista? I don't find anything about this issue (apple-doc, Stack Overflow, ...).
The Problem is:
On the created ViewController the user set some form-Elements and if the ViewController would be called again, the form-elements has the initial settings :(
Any help would be appreciated.
Edit:
I appreciate the many responses. Meanwhile, I'm not familiar with the project and can not check your answers.
Use shouldPerforSegueWithIdentifier to either allow the segue to perform or to cancel the segue and manually add your ViewController. Retain a pointer in the prepareForSegue.
... header
#property (strong, nonatomic) MyViewController *myVC;
... implementation
-(BOOL) shouldPerformSegueWithIdentifier:(NSString *)identifier sender:(id)sender{
if([identifier isEqualToString:#"MySegueIdentifier"]){
if(self.myVC){
// push on the viewController
[self.navigationController pushViewController:self.myVC animated:YES];
// cancel segue
return NO;
}
}
// allow the segue to perform
return YES;
}
-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if([segue.identifier isEqualToString:#"MySegueIdentifier"]){
// this will only be called the first time the segue fires for this identifier
// retian a pointer to the view controller
self.myVC = segue.destinationViewController;
}
}
To reuse an existing UIViewController instance with a segue create the segue from scratch and provide your own (existing) destination (UIViewController). Do not forget to call prepareForSegue: if needed.
For example:
UIStoryboardSegue* aSegue = [[UIStoryboardSegue alloc] initWithIdentifier:#"yourSegueIdentifier" source:self destination:self.existingViewController]
[self prepareForSegue:aSegue sender:self];
[aSegue perform];
Following code makes singleton view controller.
Add them to your destination view controller implementation, then segue will reuse the same vc.
static id s_singleton = nil;
+ (id) alloc {
if(s_singleton != nil)
return s_singleton;
return [super alloc];
}
- (id) initWithCoder:(NSCoder *)aDecoder {
if(s_singleton != nil)
return s_singleton;
self = [super initWithCoder:aDecoder];
if(self) {
s_singleton = self;
}
return self;
}
I faced this problem today and what I have done is to create the view controller manually and store it's reference.
Then every time I need the controller, check first if exists.
Something like this:
MyController *controller = [storedControllers valueForKey:#"controllerName"];
if (!controller)
{
controller = [[UIStoryboard storyboardWithName:#"MainStoryboard_iPhone" bundle:NULL] instantiateViewControllerWithIdentifier:#"MyControllerIdentifierOnTheStoryboard"];
[storedControllers setValue:controller forKey:#"controllerName"];
}
[self.navigationController pushViewController:controller animated:YES];
Hope it helps.
Create a property for the controller.
#property (nonatomic, weak) MyController controller;
And use some kind of lazy initialization in performSegueWithIdentifier:sender
if (self.controller == nil)
{
self.controller = [MyController alloc] init]
...
}
In this case, if controller was already created, it will be reused.
Firstly you would be going against Apple's design in Using Segues: "A segue always presents a new view controller".
To understand why it might help to know that what a segue does is create a new view controller and then the perform calls either showViewController or showDetailViewController depending on what kind of segue it is. So if you have an existing view controller just call those methods! e.g.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
Event *object = [self.fetchedResultsController objectAtIndexPath:indexPath];
self.detailViewController.detailItem = object;
[self showDetailViewController:self.detailViewController.navigationController sender:self];
}
You would need to make the Viewcontroller into a singleton class.
I'm adding a button in the middle of my initWithNibName:bundle:, when i add the button view to self.view, the view goes to start to initialize before it add's the button. So the Code in viewDidLoad gets fires before the initWithNibName:bundle: is finished. There is code below the addSubview that is relied on in the viewDidLoad and causes it to crash/not work since the init code has not run.
I've had the same experience when I added the button code to the viewDidLoad method. There is a UITableView in the .xib and the table gets inited before the rest of the viewDidLoad gets run and caused the tableView to get bad Data.
What is the best practice for adding a view to a view when you are initing and loading the view? just put all the addSubViews before the Return?
Thanks!
Here is my initWithNibName:bundle:
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{
self = [super initWithNibName:nibNameOrNil bundle:nil];
[self setIoUIDebug:(IoUIDebugSelectorNames)];
if (IoUIDebug & IoUIDebugSelectorNames) {
NSLog(#"%# - %#", [self description], NSStringFromSelector(_cmd) );
}
CGRect frame = CGRectMake(20, 521, 500, 37);
saveButton = [UIButton newButtonWithTitle:NSLocalizedStringFromTable(#"Save Animation Label",#"ScreenEditor",#"Save Animation Label")
target:self
selector:#selector(saveButtonPressedAction:)
frame:frame
image:[UIImage imageNamed:#"BlueButtonSmall.png"]
imagePressed:[UIImage imageNamed:#"BlueButtonSmallPressed.png"]
darkTextColor:NO];
[self.view addSubview:saveButton]; // <- Right here I'll hit breakpoints in other parts of viewDidLoad and cellForRowAtIndexPath, before the lined below get executed.
[saveButton setEnabled: NO];
[saveButton setUserInteractionEnabled: NO];
newAnimation = nil;
selectedSysCDAnimation = nil;
selectedIoCDTag = nil;
animationSaved = NO;
return self;
}
You should add the subviews inside viewDidLoad this will mean that the views are added when the main view is loaded into memory. I would reserve your initWithNibName:bundle: call for custom initialization and not interacting with the UI as this what viewDidLoad is designed for.
In regards to your tableView, you should put a call to load the tables datasource inside of viewDidLoad. Once the datasource is loaded, you can simply call reloadData on the tableview to load the data into the tableview.
For Example:
- (void)viewDidLoad
{
[super viewDidLoad];
[self.view addSubview:saveButton];
[self loadDataSource];
}
- (void)loadDataSource {
// load datasource here
[self.tableView reloadData];
}
Any access to the view property of the view controller will lazily initialize the view. This will trigger a call to viewDidLoad which will execute before the access to the view property returns in initWithNibName:. You should add the sub view in viewDidLoad or using interface builder.