In my UIViewController named MainViewController, I have a reference to another UIViewController named SubViewController. It is defined as follows:
#class SubViewController;
#interface MainViewController : UIViewController <UIScrollViewDelegate> {
SubViewController * _subViewController;
}
In the initWithNibName:bundle: method of my MainViewController, I initialize my SubViewController as follows:
#pragma mark - Init
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil; {
if((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])){
_subViewController = [[SubViewController alloc] initWithNibName:#"SubViewController" bundle:nil[;
// Forces the view to load, in an attempt to speed up the adding of the subview.
UIView * view = _subViewController.view;
view.alpha = 1.0f;
}
return self;
}
The viewDidLoad method of the SubViewController does get called, and everything seems to be loaded, but when I add the SubViewController as a subview:
- (IBAction)showButtonPressed:(UIButton *)aButton; {
[self.view addSubview:_subViewController.view];
}
The app slows down for a couple of seconds, and then the subview is added and everything is fine. The strange thing is, when I remove the subview and try to re-add it again, there is no delay!
I assume the issue is a loading one, but I can't find any documentation on how to solve this.
Can anyone explain what is causing this slow down? Thanks!
your code its not complete !!
i try to take your code and make new project -ARC- and its fain to me no delay at all
try to use Instruments to find whats happen
I never had issues like that. since you are saying if you don't load the second view it works faster. check to see what is in the viewWillAppear and viewDidAppear for the secondViewController
Related
I've done this many times with code that is exactly the same, but for some reason it isn't working today.
ExampleViewController1 *exampleView = [[ExampleViewController1 alloc] initWithNibName:#"ExampleViewController1" bundle:nil];
[exampleView setProjectName:[[self.projectListArray objectAtIndex:indexPath.row] objectForKey:#"name"]];
NSLog(#"%#", [[self.projectListArray objectAtIndex:indexPath.row] objectForKey:#"name"]);
XAppDelegate.stackController pushViewController:exampleView fromViewController:nil animated:YES]
My NSLog prints out appropriately.
My ExampleViewController1.h file declared like:
#property(nonatomic, strong) NSString *projectName;
I then do this code in ExampleViewController1.m's
-(void)viewDidLoad {
NSLog(#"%#", self.projectName);
self.projectNameLabel.text = self.projectName;
[super viewDidLoad];
}
The results of my NSLogs are curious. The NSLog from my viewDidLoad appears to be getting called before my other one:
2012-04-22 10:59:41.462 StackedViewKit[43799:f803] (null)
2012-04-22 10:59:41.463 StackedViewKit[43799:f803] NewTest
I have confirmed that the (null) value there is from NSLog(#"%#", self.projectName);, but that should be the second NSLog called...I can't figure out why it is coming through first.
Someone requested this code:
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) {
// random color
self.view.backgroundColor = [UIColor colorWithRed:((float)rand())/RAND_MAX green:((float)rand())/RAND_MAX blue:((float)rand())/RAND_MAX alpha:1.0];
}
return self;
}
As I expected, the problem is that you are trying to access self.view inside the initialization method. So move the line self.view.backgroundColor = ... to the viewDidLoad method:
- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(#"%#", self.projectName);
self.projectNameLabel.text = self.projectName;
self.view.backgroundColor = [UIColor colorWithRed:((float)rand())/RAND_MAX green:((float)rand())/RAND_MAX blue:((float)rand())/RAND_MAX alpha:1.0];
}
In fact, the documentation of the view property says:
If you access this property and its value is currently nil, the view controller automatically calls the loadView method and returns the resulting view.
So when you call self.view in the initialization method, the view controller will have to load the view (from the nib or using the loadView method). And that's why viewDidLoad is called.
viewDidLoad is called before a view controller is displayed for the
first time, not immediately after initWithNibName.
> viewDidLoad method is called after the view controller has loaded its view
hierarchy into memory. This method is called regardless of whether the
view hierarchy was loaded from a nib file or created programmatically
in the loadView method.
> initWithNibName The nib file you specify is not loaded right away. It
is loaded the first time the view controller’s view is accessed. If
you want to perform additional initialization after the nib file is
loaded, override the viewDidLoad method and perform your tasks there.
You can use App delegate to pass the data from one to another, that is another alternate solution.
you do in initWithNibName method itself. or in viewDidAppear.
Your initWithNibName method should be like this as per as #sch comments;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil] //just set it here first and then check
if (self) {
// do something here;
}
return self;
}
We just need to be smart enough to think about what do we need to in constructor and what do we need to at viewDidLoad (once it had loaded into memory)
I have created a new project in XCode and used the new Storyboard-feature to create two different View Controllers.
The first View Controller is attached to the main files (ViewController.h, Viewcontroller.m). The second View Controller is attached to it's own set of .h/.m files (NewUserController.m/.h)
Now for the problem which I havent been able to find a solution for in the last hours;
I have added a button the second view controller and attached the button to an IBAction (verifyNumber). When I attach the 'Touched Up Inside' event the IBAction is never fired. However, when I attach the 'Touch Down' everything works fine..
Both View Controller's have got the 'user interaction enabled' selected and apart from the button the second view controller doesn't contain any other elements. Also, my manual performSegueWithIdentifier is working (switch from view1 to view2).
Can anyone spot where it has gone wrong?
The code:
ViewController.m
- (void)firstStartup {
// Future use for getting userID
// Switch to loginview
[self performSegueWithIdentifier:#"segueLogin" sender:self];
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
// Fire firstStartup
[self firstStartup];
}
NewUserController.h
#import <UIKit/UIKit.h>
#interface NewUserController : UIViewController
#property (weak, nonatomic) IBOutlet UITextField *inputNumber;
- (IBAction)backgroundTap;
//- (IBAction)verifyNumber;
- (IBAction)verifyNumber:(id)sender;
#end
NewUserController.m
#import "NewUserController.h"
#implementation NewUserController
#synthesize inputNumber;
// Collect User data & Start Request
- (IBAction)verifyNumber:(id)sender; {
inputNumber.text = #"testing";
}
- (IBAction)backgroundTap {
[inputNumber resignFirstResponder];
}
UPDATE
Because of the response of NJones I have tested some more and deleted the gesturerecognizer I had present on the second view. After deleting this recognizer the UIButton works with all events (Touched Up Inside).
Does the recognizer somehow block any 'tap' events to overlaying objects (such as the UIButton)?
I have a few thoughts,
1) Why do you have:
- (IBAction)backgroundTap;
//- (IBAction)verifyNumber;
- (IBAction)verifyNumber:(id)sender;
There is a difference between verifyNumber and verifyNumber:(id)sender and they can both exist at the same time, and both can be connected in the nib.
2) Are you using any UIGestureRecoginzers on the view at all?
3) Is this button a custom button or subclass of UIButton?
4) (I truly don't think this will help solve your problem it's just good practice, and I'm already typing :)) Using a view property to check if a method was called is inconclusive at best. Try putting a log statement in the IBAction method like So:
- (IBAction)verifyNumber:(id)sender; {
NSLog(#"verifyNumber:");
inputNumber.text = #"testing";
}
I have the relatively common setup of a TabBarController whose tabs contain NavigationControllers which have TableViewControllers as their roots. I'm trying to perform some logic on initialization of one of these TableViewControllers but can't seem to find what init function gets called.
My goal is to add a listener in the TableViewController (that I have subclassed) which can respond to events by updating the navigationController.tabBarItem.badgeVluew property.
I've tried putting code into initWithStyle: as well as init but neither of them end up getting called. I've also tried putting it in viewDidLoad, but that only gets called once the controller actually appears (I need to have it happen as soon as the controller is loaded / as soon as the tab bar item shows up).
Does anyone know where I would put this code for it to happen on initialization of the controller?
Also, this is all set up through interface builder / NIBs. I'm not adding the nav controller or tableviewcontroller manually, which is why it's not clear what init function I need to override.
If you select one of your UITabBarItems in IB, you will see 'View loaded from "YourView"'. Click into this "gray" View. In the Inspector window you will see in the Attributes Tab (the tab on the left) the title and the NIB name which will be loaded (lets call it "YourNibName").
Now select the right tab of the inspector (Identity) and change the Classname (Combo next to Class) to your "YourViewController" class, which you must create in xcode. Don't use the standard ViewController, which is already selected. The InterfaceBuilder loads your nib and attaches it to your ViewController.
Open YourNibName and change FilesOwner's Class (Inspector, right Tab) to "YourViewController", too.
Your TabBar's NIB contains a FilesOwner, too. Create a ViewController for this FilesOwner and set its Class to this Controller (i.e. TabBarController)
In "TabBarController" you can find out which Tab was selected by using this code:
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController{
if ([viewController.nibName isEqualToString:#"NIBName1"]){
// Do something here, if you like. (i.e. Save the state in a string or int)
}
if ([viewController.nibName isEqualToString:#"NIBNAme2"]){
// Do something here, if you like. (i.e. Save the state in a string or int)
}
...
}
Here you can do something "global" or preinitialize something. This is ONE thing you can do.
INIT OF YOUR VIEWS:
If you select a Tab and the view (which is handled by YourViewController) will be shown for the first time, "viewDidLoad" will be called in "YourViewController"
- (void)viewDidLoad {
// Here you can add views programatically
[self.view addSubview:myNavigationController.view];
[self.view bringSubviewToFront:myNavigationController.view];
// And if you like, do some INIT here
[super viewDidLoad];
}
I hope this is what your question was about.
Now something about the badge. It's a hack, but works fine for me.
Header file:
Add an outlet to your controller, which is representing your TabBarController:
#interface yourController : UIViewController <UITabBarControllerDelegate> {
UITabBarController *tabBarController;
}
#property (nonatomic, retain) IBOutlet UITabBarController *tabBarController;
#end
Connect this outlet in IB with your TabBar.
Implementation:
In your TabBarControllerClass you can overwrite 'initWithNibName':
#synthesize tabBarController;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {
// Do some init here
// select your desired item (it will be loaded)
// then you can assign the badge
tabBarController.selectedIndex = 1;
tabBarController.selectedViewController.tabBarItem.badgeValue = #"222";
// and select the item you will start with
tabBarController.selectedIndex = 0;
// if you like you can add a notification, which you can activate from anywhere else
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(itemBadgeChanged:)
name:#"itemBadgeChangedNotification"
object:nil];
}
return self;
}
if you don't use nib, use '- (void)loadView { ... }' instead.
You are using a subclass of the TabBar controller, maybe you can use 'self.selectedIndex = 1;' instead of 'tabBarController.selectedIndex = 1;', and so on. Just try this out
Hope this helps!
I need to create my own UIView class and it is not something I have had to do. I created the class, then laid out the small view in IB (it's just a few labels that i will later need to add data to ). but now im stuck on how to actually put an instance of it in my main view. Can someone point me in the direction of a good tutorial? The closest thing I have done to this is creating a custom tableViewCell.
DataTagViewController.m:
- (id)initWithNibNamed:(NSString *)DataTagViewController bundle:bundle {
if ((self = [super initWithNibName:DataTagViewController bundle: bundle])) {
// Custom initialization
}
return self;
}
MapView.m:
DataTagViewController *dataTag = [[DataTagViewController alloc] initWithNibNamed:#"DataTagViewController" bundle:nil];
[theMap addSubView: dataTag.view]; <<< this line causes the crash (theMap is a UIView)
I now get this runtime error when adding the subview:-[UIView addSubView:]: unrecognized selector sent to instance 0x470f070'
2010-06-06 21:22:08.931
UIViewController is not a view, but controls a view. If your DataTagViewController class extends UIViewController, then you'll want to add it's view, not the class itself:
[theMap addSubView:dataTag.view];
Also, do you have a DataTagViewController.xib file created that has your view in it? If you don't, you'll need to create one and use the UIViewController's initWithNibName:bundle method. Otherwise, you'll have to implement the loadView method instead to provide your own view via code.
Edit
Your init function is using the name of your class as a variable. That probably won't work. Use the default sigature:
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])
{
}
}
If you aren't doing anything beyond the init function, you don't need to implement this method. Your alloc/init statement is enough.
For a good tutorial, read the View Controller Programming guide in the docs.
What is the parent class of DataTagViewController? You say you need to create "my own UIView class", but your example suggests that you actually want to create UIViewController subclass. initWithNibNamed: is UIViewController method. If your parent is UIView, then "unrecognized selector" makes sense.
I am having difficulty geting a very simple view to display. This view has a custom view controller that is manages by a switching view controller. The XIB has one UIViewController component on it with its Image property set. The view controller is as follows:
InstructionsViewController.h
#import <UIKit/UIKit.h>
#interface InstructionsViewController : UIViewController {
}
#end
InstructionsViewController.m
#import "InstructionsViewController.h"
#implementation InstructionsViewController
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationLandscapeRight);
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview
// Release anything that's not essential, such as cached data
}
- (void)dealloc {
[super dealloc];
}
#end
I have also set the class property for the XIB's File's Owner to InstructionsViewController, and Ctrl+Dragged File's Owner to the View icon and selected View from the popup menu.
The code to display the view is:
- (void) showInstructions
{
//Lazy load the instruction view.
if (self.instructionsViewController == nil)
{
InstructionsViewController *viewController = [[InstructionsViewController alloc]
initWithNibName:#"InstructionsView"
bundle:nil];
self.instructionsViewController = viewController;
[viewController release];
}
[self.view insertSubview:viewController.view atIndex:0];
}
My view controller that animates different views when they are switched, has no problems loading and displaying three other views. It just doesn't like this one.
I'm sure I've missed something simple, but for the life of me I can't get it to work for some reason. Does anyone have any pointers?
Thanks,
Steve
I just had the same thing. Ended up deleting the UIImageView, placing a new one then relinked and it worked. Seems like some corruption somewhere.
Not even really sure how this is compiling. You are inserting the subview outside of your nil check, where viewController is out of scope.
You probably want to do
[self.view insertSubview:self.instructionsViewController.view atIndex:0];
Have you verified that showInstructions is being called by setting a breakpoint there? One other thing to check is that you are inserting the Instructions view at the bottom of your z-order, so it will be behind all other items. Try using:
[self.view addSubview:self.instructionsViewController.view];
This will add it to the top of the z-order. If that doesn't work, also try:
[self.view setNeedsLayout];
and/or:
[self.instructionsViewController.view setNeedsLayout];
Ok, I've finally solved it!
The problem was something in XCode or Interface Builder was not agreeing with the PNG file I specified for the Image View control in IB. I tried re-naming, and re-specifying, etc. to no avail.
I finally had to delete the graphic and re-copy it from it's source location. Then I re-specified it in Image View, build and ran. Now it works.
Everything is good in the world again.
Thanks to those who took the time to read and offer help. I appreciate it very much!
Steve