I have a class with a viewDidLoad method and an artworkInfo method as follows:
-(void)viewDidLoad {
mainDelegate = (AppDelegate*)[[UIApplication sharedApplication]delegate];
[super viewDidLoad];
}
-(void)artworkInfo:(NSNumber *)pos{
mainDelegate = (AppDelegate*)[[UIApplication sharedApplication]delegate];
[self.image setImage:(UIImage *)[[mainDelegate.mapAnnotations objectAtIndex:0]image]];
}
the mainDelegate thing is to gain access to the appDelegate where an array is stored, but anyway, with the "[self.image setImage...]" command where it is, the image on the app does not appear, but when I copy that exact line of code into the viewDidLoad method, it shows up like it should. I know that the artworkInfo method is being called because I debugged it and it goes through, so I can't figure out why the command would not be doing anything it's current method while it will in the viewDidLoad...?
Also, here is where the method is called and this new view is loaded from another class:
infoPage *info = [[infoPage alloc] initWithNibName:#"infoPage" bundle:nil];
info.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self presentModalViewController:info animated:YES];
infoPage *myInfoPage = [[infoPage alloc] init];
[myInfoPage artworkInfo:position];
[info release];
OH, I see the problem. You're instantiating 2 different infoPage classes.
Change this:
infoPage *info = [[infoPage alloc] initWithNibName:#"infoPage" bundle:nil];
info.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self presentModalViewController:info animated:YES];
infoPage *myInfoPage = [[infoPage alloc] init];
[myInfoPage artworkInfo:position];
[info release];
to this:
infoPage *info = [[infoPage alloc] initWithNibName:#"infoPage" bundle:nil];
info.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self presentModalViewController:info animated:YES];
[info artworkInfo:position];
[info release];
Ok detailed answer. In order to understand why this image is not displaying properly you have to first look at how Runloops work in Objective C.
While viewDidLoad is the method that is called when a view is loaded and it is technically also called before a view is displayed and it's view objects initialized. Since presentModalViewController is an animation there is actually some threading going on in the works.
viewDidLoad gets called before the animation is created for the presentModalView. This initializes your objects. However, due to some of the inner workings of UI Kit some processes are loaded off into a thread. When they complete they run callback methods on the main UI thread.
Since presentModalViewController is a non-blocking method your artworkInfo method gets added to the mainRunLoop before the initializer form thread adds its callback methods to the main run loop. The best approach would be to have both a UIImage property of your viewController and a UIImageView.
set the value of UIImage by calling artworkInfo BEFORE the presentModalViewController method.
in your ViewDidLoad go ahead and set the value of your UIImageView
[self.imageView setImage:self.image];
Problem solved.
This seems pretty straight forward.
So you initialize your nib and try to call your method artwork before the nib is fully loaded. <-- This is not working for you.
Then you do additional initialization by overrider viewDidLoad per the doco where the nib is loaded <-- This is working for you
So the answer is, when you call setImage before your nib is loaded, then there is nothing to set the image to. When you call setImage in viewDidLoad your nib is loaded and then things should work just fine.
I hope this explains it a bit.
Related
I have created a custom UIViewController class that creates a ScrollView at runtime that it loads into the view. See code here in the constructor of my custom UIViewController.
initControl(id, canEdit);
_controllers = new NSMutableArray(0); //required to keep view controllers around
_scrollView = new UIScrollView();
_scrollView.BackgroundColor = UIColor.Green;
this.View = _scrollView;
ViewDidAppear and ViewWillAppear are called normally.
ViewDidLoad is not called which I am not sure why as the view is showing up on the screen just fine.
Any ideas?
The viewDidLoad method is being called when accessing self.view
Examples:
1)
- (id) init {
self = [super init];
if (self)
{
...
[self.view addSubview: self.toolbar];
}
}
2)
viewContrl = [[MyViewController alloc] init];
viewContrl.view = webTopView;
3)
viewContrl = [[MyViewController alloc] init];
[viewContrl.view addSubview: webTopView];
ViewDidLoad is called when you are allocating the view. So if you are allocating the view once & only adding every time using addSubview then it called first time only. If you want to called it every time when you are adding it, then you needs to allocate it every time. Also handle memory management by releasing the view before allocating it, if it is already allocated.
Another way is to create a method which contains the operations which you wants to perform & called it after addSubview.
It may solves your problem, if you have any doubt then feel free to ask me.
I am properly pushing viewController B from A using navigationController. However, I would like to do it once uiwebview from viewController B finishes its load and not immediately. I tried firstly init B and push A when load ends but with no success, controller is not viewed. How can it be done? thank you.
from controllerA,
self.controllerB = [[BViewController alloc] initWithNibName:#"BViewController" bundle:nil anUser:self.idUser aLang:self.lang];
//[[self navigationController] pushViewController:controllerB animated:NO]; working if pushed directly here
[self.controllerB view];
then, controllerB is initialized, viewDidLoad triggered and when webviewDidFinishLoad, B must be pushed now or viewed at front.
- (void)webViewDidFinishLoad:(UIWebView*)theWebView
{
AViewController *theInstance = [[AViewController alloc] init];
[theInstance pushBcontroller]; }
on AViewController,
-(void)pushBcontroller{
[[self navigationController] pushViewController:self.controllerB animated:NO];
}
not working...
The line AViewController *theInstance = [[AViewController alloc] init]; creates a new instance of a AViewController. Since it's new it isn't part of the view controller hierarchy and is therefore not connected to the navigation controller.
Give your BViewController a reference to the previous controller and use that instead of creating a different one. Or, perhaps better, send a notification when loading is done that the original AViewController uses to know when to change the display.
I apologize in advance for the n00b question. I am just getting started w/ iOS!
I am trying to push a webViewController onto a navigation controller.
mudWebViewController *webViewController = [[mudWebViewController alloc] initWithNibName:nil bundle:nil];
[[webViewController webView] setDelegate:webViewController];
[[self navigationController] pushViewController:webViewController animated:YES];
But this doesn't seem to work, as I don't see any of the logs in the delegate messages.
If I set the delegate in the viewDidLoad: method, it works fine.
I guess the webView doesn't actually exist at that point, but why? If I initialize the controller, shouldn't the webView be initialized too?
Is viewDidLoad: the right place to be setting up this stuff?
initWithNibName should be not nil, since you obviously are using a nib file to build the view, else you have to create the view in code, which you don't
mudWebViewController *webViewController = [[mudWebViewController alloc] initWithNibName:#"webViewController" bundle:nil];
[[self navigationController] pushViewController:webViewController animated:YES];
Also any delegates should be set either from the Interface builder or from the view itself in the viewDidLoad delegate and not from the previous class, as the object might not been yet initialized in the code so it can fail to set the delegate properly.
I dont want to add a sub view, but instead change the "self.view" to another view eg (A warning view) then after the user suppresses the warning I would like to switch back. When ever i try to switch back to the original view i just get a blank screen for reasons i cant understand.
Here is what i currently have in one of my UITableViewControllers
//Show warning view controller
self.warningViewControler = [[[WarningViewController alloc] init] autorelease];
self.view = self.warningViewController.view;
//Then later
self.view = self.tableView; //<< Dosnt work
If you want to change your view, and if the original view is defined/linked into XCode, you must retain it before changing self.view to another view. If not, the original view is released and using it back can cause bad things to happen.
Warning :
self.warningViewControler = [[[WarningViewController alloc] init] autorelease];
self.view = self.warningViewController.view
is a bad bad call. Because you autorelease the controller but you use its view. So you get a view retained with a released controller after some time. Retain the controller and release it yourself when its view is not needed anymore.
Here's the better way to do what I think you're trying to do:
WarningViewController *warningViewController = [[WarningViewController alloc] initWithNibName:#"theRightNiborNil" bundle:nil];
[self presentModalViewController:warningViewController animated:YES];
// or if you don't need to support iOS4 any more:
[self presentViewController:warningViewController animated:YES completion:nil]
// and if you aren't using ARC yet, then [warningViewController release];
Then in your WarningViewController you want some action that calls:
[self dismissModalViewControllerAnimated:YES];
// or again if this is iOS5..
[self dismissModalViewControllerAnimated:YES completion:nil];
Hope that helps.
I am new at Objective C. I am just trying to build an iphone app. I have created some NIB file, and i have gone to other NIB file by creating an object and using this code:
scoreViewController *sviewController = [[scoreViewController alloc] initWithNibName:#"scoreViewController" bundle:nil];
self.scoreView = sviewController;
[sviewController release];
// Setup the animation
[self.navigationController pushViewController:self.scoreView animated:YES];
Now I want to come back to the same page. For this case I have done the same work, but it does not work when I add the previous page header file name.
mainViewController *mainviewController = [[mainViewController alloc] initWithNibName:#"mainViewController" bundle:nil];
self.mcoreView = mainviewController;
[mainviewController release];
// Setup the animation
[self.navigationController pushViewController:self.mcoreView animated:YES];
So, I will be most grateful if you were so nice to post your comment.
I am not 100% sure what you are asking, but I think you want to go back from the the second controller to the first. What you are doing here is instantiating a second instance of the first controller (so you now have 3 controllers), and pushing it onto the stack. Assuming I have this correct, then if you want to move back to the first controller you should be popping the second controller off the stack, not adding a 3rd:
//mainViewController *mainviewController = [[mainViewController alloc] initWithNibName:#"mainViewController" bundle:nil];
//self.mcoreView = mainviewController;
//[mainviewController release];
// Setup the animation
[self.navigationController popViewControllerAnimated:YES];