My problem is that I cannot access any of the controls in a view defined using interface builder. This is the .h code for the Navigation bar (as an example):
#import <UIKit/UIKit.h>
#interface myController : UIViewController {
IBOutlet UINavigationBar *tTitle;
}
#property (nonatomic,retain) UINavigationBar *tTitle;
#end
The implementation (.m) is:
#import "myController.h"
#implementation myController
#synthesize tTitle;
- (void)dealloc {
[tTitle release];
[super dealloc];
}
- (void)viewDidLoad {
tTitle.topItem.title=#"This is my title";
}
In viewDidLoad tTitle (and my other outlets) are always 0x0. I have omitted the two text fields and the button for brevity.
This exact code works in another view in the app without issue. In IB I right click on the file owner icon and it shows my outlets correctly (and the single button action). Yet at run time - nada. I click the button and no response. The title is still the default title. I cannot set the text fields text property because the fields are all 0x0.
The view is linked to the view controller. As near as I can tell everything is identical between the two views that are doing the same thing. Obviously something is awry, but I can't figure it out. Any help would be appreciated.
Okay. I did the ROI and figured it would be easier to delete and recreate the view (one control at a time) in an attempt to see where it was going awry. The answer is the title bar title set worked from the get-go. I have no idea why the other class didn't work. But discretion is the better part of valor in this situation. The new class is working fine. Thanks for everyone's input.
Related
When I add new view, I always do same and boring work.
If I add UIWebView, I would do follows,
add codes to header file. ( declare, property )
add codes to source file. ( synthesize, viewDidUnload, dealloc )
add UIWebView in IB and connect to the outlet in File's Owner.
[ViewController.h]
#interface ViewController : UIViewController
{
UIWebView *_webView;
}
#property (nonatomic, retain) IBOutlet UIWebView *webView;
#end
[ViewController.m]
#synthesize webView = _webView;
- (void)viewDidUnload
{
[super viewDidUnload];
self.webView = nil;
}
- (void)dealloc
{
[_webView release];
[super dealloc];
}
What if I should add 3 labels and 2 buttons?
What if I have to add textview and some imageviews?
Don't you think it is boring? I would like to listen to your idea.
I hope there will be more easy and simple way to add outlet to the code.
Does anybody have a good idea? :)
When using Interface Builder, If you select an Object drag it's reference to your header, you'll see a popup where you can name it so theres less typing for you to do. As seen below:
This will automatically declare the IBOutlet UIButton *myButton for you, and insert the release and nil code into dealloc and viewDidUnload methods.
Same method also works for actions, as seen below.
Once you Connect it will automatically insert the new Action -(IBAction)cancelSelected:(id)sender into your #implementation class.
Point being, all that's boring for you to do can be done in 2 Reference connections, and inputting data into 2 fields. :)
Hope this helps!
In Xcode 4, you can simply control drag from a UI element to the .h/.m file. If you drag to the .h, Xcode will create a property for you and synthesize that in the corresponding .m, if you drag to the .m, Xcode will stub out an IBAction method for you.
Also, I would recommend switching to ARC, to avoid having to worry about memory management.
If you are having xcode 4.0 you can create outlet property by drag and drop.
Follow the steps:
open the xcode
open you nib file where you need to create an outlet.
Click on the middle tab of the Editor which at right up corner. It will open a new file adjacent to your nib.
Make sure it is the .h file of the controller where you want to create the outlet.
Now select the control, right click on it and drag to the .h file. Name the outlet. Thats it. It will create you a property and it will synthesize it automatically.
It will also insert the code for dealloc and viewDidUnload.
Hope this help.
I am trying to use storyboards in my application. I began well, I have added two view controllers with a button to go from the first to the second.
The problem is in this second view controller: the objects I add on it and link with the code do not work. When I set a breakpoint in the view controller code, the 'self.property' is set to nil, whereas it should be instantiated by the storyboard.
I have been looking for an answer for hours, and I really don't understand the problem, since all the rest seems to be good.
I have tried to write the property in the code (strong/nonatomic, nonatomic/retain and even weak/nonatomic), to link the object directly to the code so that it creates the property automatically, but I never get anything else than "nil" with breakpoints.
viewController.h:
#interface NMLoadingViewController : UIViewController
{
__weak IBOutlet UIProgressView *imageProcessingProgressView;
}
#property (weak, nonatomic) IBOutlet UIProgressView *imageProcessingProgressView;
#end
.m:
#synthesize imageProcessingProgressView;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
// Custom initialization
NSLog(#"INIT.");
}
(amont other lines of irrelevant code)
If I set the breakpoint to the "INIT." line, my imageProcessingProgressView is nil. I can't see a reason for that, I guess I have missed a very little detail...
(Note that I have tried this with other objects, like a UILabel, but it did not work either. Stranger, when I had two objects, one of them had an adress which was not nil, but still it was corrupted and did not show the right object.)
Edit: It was a lot of trouble for nothing... The problem is about the Variable View in XCode, which show my variable to "nil", whereas a log shows me a correct object...
Remove this...
{
__weak IBOutlet UIProgressView *imageProcessingProgressView;
}
...and make the property strong.
Change your log message to...
NSLog(#"INIT: %#", self.imageProcessingProgressView);
...and see if you still have a problem. If you do, then take another look at your storyboard connections.
Make sure NMLoadingViewController is the class on your viewController
First try out the answer by #Eric because I do believe that is the real issue.
Also, make sure that you are actually using the interface builder to hook the controls back to the view controller. This is done by dragging a line from the control back to the property of the view controller.
UPDATE - Cause found!... please read below & suggest the solution:
While creating a video to show this issue, I have found why does that happen...
Any Control/Element that is defined between #imports & #implementation DetailViewController in .m file is lost by the original detVC when a new instance is created of VC.
Example:
I am including a video that re-creates this issue. As shown, all controls work except a UISegmentedControl & a UILabel.. both of which are defined in DetailViewController.m as:
#import "DetailViewController.h"
UISegmentedControl *sortcontrol;
UILabel *incrementLabel;
#implementation DetailViewController
Video Link - http://www.youtube.com/watch?v=2ABdK0LkGiA
I think we are pretty close.. Waiting for the answer!!
P.S.: I think this info is enough can lead us to the solution, but if needed I can share the code too.
EARLIER:
There's a detailViewController (detVC) in our app which is normally 'pushed' from a UITableViewController.
Now we are also implementing Push Notifications which would 'modally' present the same detVC whenever the notification arrives, which in turn can happen over any view controller.
It works all fine until the detVC through notification is presented while another instance of detVC was already the active view controller (pushed earlier through TableView).
The problem happens when the presented detVC is dismissed - the pushed detVC 'looses' control of about everything - It is not pointing to the same data as earlier & even the UISegmentedControl on Navigation Toolbar points to -1 index on pressing any index!
Why does such thing happen when we are creating a separate instance of detVC? Why does it affect the earlier detVC? How can it be resolved / What about Objective C needs to be learned here? (FYI, we are using ARC in the project)
Thanks
EDIT - Some code:
When Pushed:
ProductDetailViewController *detailViewController = [[ProductDetailViewController alloc] init];
detailViewController.hidesBottomBarWhenPushed = YES;
[self.navigationController pushViewController:detailViewController animated:YES];
detailViewController.serverOffset=serverOffset;
detailViewController.prdctIndex = indexPath.row;
When presented through Notification:
- (void)displaySingleProduct:(NSDictionary*)userInfo{
ProductDetailViewController *onePrdVC = [[ProductDetailViewController alloc] init];
UINavigationController *addNav = [[UINavigationController alloc] initWithRootViewController:onePrdVC];
onePrdVC.justOne=YES;
onePrdVC.onePrdIDtoLoad=[[[userInfo valueForKey:#"prd"] valueForKey:#"id"] intValue];
[self.navigationController presentModalViewController:addNav animated:YES];
}
There is a Product class in detVC which gets the data from the values stored at the prdctIndex row in the SQLite table.
After dismissing the presented detVC through notification, the Product class of the pushed detVC starts pointing to the row which was used for Product class in presented detVC. And there is no such code in viewDidAppear which would alter Product class.
So, this, UISegmentedControl issue mentioned above & some other problems are causing the pain! Basically, the whole detVC acts weird - which re-works if we just pop & re-push it!
EDIT 2
I have more info on it which could lead to the cause.
If I run viewDidLoad on viewDidAppear like this:
if (!justOne) {
aProduct = [allProducts getProduct:(prdctIndex+1) one:NO];
[self viewDidLoad];
[self populateDetails];
}
the pushed detVC regains the control & every element/control starts re-working as expected (but not in the ideal way). So, it is quite clear that the separate instance of presented detVC does messes up the earlier pushed detVC & a re-setting up of all the controls / pointers is required through viewDidLoad.
Can any helpful conclusion can be derived from this info?
When in your code you write:
#import "DetailViewController.h"
UISegmentedControl *sortcontrol;
UILabel *incrementLabel;
#implementation DetailViewController
You are not defining these variables as instance variables (ivars), so they are not individual for each instance. There are three ways to define ivars.
1) The traditional way, in your .h file.
#interface DetailViewController{
UISegmentedControl *sortcontrol;
UILabel *incrementLabel;
}
2) Some additions to objective-C have added support for the next two ways. Like declaring them in your .m file.
#implementation DetailViewController{
UISegmentedControl *sortcontrol;
UILabel *incrementLabel;
}
3) If these ivars use properties to expose them, then you can simply leave out the explicit definition of them. So in .h:
#interface DetailViewController
#property (strong, nonatomic) IBOutlet UISegmentedControl *sortcontrol;
#property (strong, nonatomic) IBOutlet UILabel *incrementLabel;
and then in the .m file:
#implementation DetailViewController
#synthesize sortcontrol;
#synthesize incrementLabel;
Are you loading the view controller from a NIB? If so, it may be that the same instance of the view controller is used each time. You can log the address of your view controller in viewDidLoad and see if this is the case.
It actually depends on how your apps architecture has been created. If you are using TabBarController based application, here is the proper way to do so.
If two instances of the same class are interfering with each other, that strongly suggests that you are not storing all your state in instance variables. I would suspect that something in ProductDetailViewController stores its state in global or class data, and that your problem lives in there.
It's possible that you have done something silly like making ProductDetailViewController a forced singleton (overriding +alloc, which you should almost never do), but generally people remember when they've done that.
Never call viewDidLoad directly. That's only for the system to call. (I know you were just testing, but don't leave that in.)
But are you calling [super viewDidAppear:animated] in your viewDidAppear:? You have to call your superclass in that method.
The context: I have three views. One Introductory view, an Upload view and the Main view. As classes (With their respective headers) I have the rootViewController (SwitchViewController), IntroViewController and UploadViewController. The first view to be shown is IntroView. The user presses a button (declared in SwitchViewController) that takes them to the UploadView, then in the UploadView they get to choose an image and press the button again to go back to IntroView.
The thing is that while the user gets to pick the image with UIImagePickerController the button to switch views won't hide nor a UIImageView I have with a logo on top of the view(screen). The UIImageView and the UIButton are both declared in SwitchViewController's header.
The code used:
UploadViewController.h
#import [...] //Imports
#class SwitchViewController;
#interface UploadViewController :
UIViewController <UIImagePickerControllerDelegate,
UINavigationControllerDelegate,UIActionSheetDelegate> {
UITextField *imageTextField;
UIImageView *uploadedImage;
SwitchViewController *switchViewController;
[...]
}
#property (nonatomic, retain) SwitchViewController *switchViewController;
#property (nonatomic, retain) IBOutlet UITextField *imageTextField;
#property (nonatomic, retain) IBOutlet UIImageView *uploadedImage;
[...]
#end
UploadViewController.m
[...]
- (IBAction) selectImageButtonPressed {
self.switchViewController.submitButton.hidden = YES;
self.switchViewController.imageLogo.hidden = YES;
[...] //continues
I just begun recently programming in objective-c so please forgive me if the question is very essential. I have looked and am following "Beginning iPhone 3 Development" of APRESS. But even if it helps to greatly understand the basics sometimes I get lost.
PS: If it is clearer to answer the question the SwitchViewController.h and .m snippet codes can be provided if asked. But I thought this text is big as it is.
#Joze i think I may have understood your problem switchViewController is a variable of the class UploadViewController so if you do anything with that variable it wont affect the switchViewController view. so when you are calling the switchViewController view at that time you have to do initWithNibName: bundle: and then hide the button and imageView and also you need to do something like switchViewController.delegate = self; and then call the view modally or what ever way you want it.
PS. i m not sure the that spelling is correct. i dont have xcode at my home.
I hope your problem solves with this.
I solved my problem after refactoring the whole code and changing the general structure of the program itself. Now I have 3 views and each with a viewController to control it. All the switching of views occurs in the Delegate since he has access to everyone. That way I can control every property with every controller, without much difficulty. Changing the property of one of the objects present in one view from another view is difficult and rather inconvenient if not sometimes impossible.
The approach I took when asking this question was short sighted for the application that had to be done. I thank all those who tried to help.
I am new to the iPhone SDK and am trying to create 3 views and switch between them. Data will come from a server and I will basically be showing 1 view and caching the other two. So far I am just trying to create a view and display it at run-time. My code is listed below. It shows only a blank screen and I think I am missing a key concept. Any Help?
#import <UIKit/UIKit.h>
#import "ImageViewController.h"
#interface Test5ViewController : UIViewController
{
IBOutlet UIView *rootView;
ImageViewController *curImage;
ImageViewController *nextImage;
ImageViewController *prevImage;
}
#property(nonatomic,retain) IBOutlet UIView *rootView;
#property(nonatomic,retain) ImageViewController *curImage;
#property(nonatomic,retain) ImageViewController *nextImage;
#property(nonatomic,retain) ImageViewController *prevImage;
#end
and
- (void)loadView
{
self.curImage = [[ImageViewController alloc]initWithNibName:#"ImageView" bundle:[NSBundle mainBundle]];
UIImage *pic = [UIImage imageNamed:#"baby-gorilla.jpg"];
[self.curImage assignImage:pic];
self.rootView = self.curImage.view;
}
and
#import <UIKit/UIKit.h>
#interface ImageViewController : UIViewController
{
IBOutlet UIImageView *image;
}
-(void)assignImage:(UIImage *)screenShotToSet;
#property(nonatomic,retain) IBOutlet UIImageView *image;
#end
Welcome to the iPhone SDK!
In general, there are two ways to get any view displayed.
First, and most commonly, you use a NIB file created by the Interface Builder. This is usually the easiest way to get started and I would recommend it for what you're trying to do here. It's too lengthy to describe all the steps you need to do for what you have here, but basically start in xcode by creating a new file and selecting "user interfaces" and choose View XIB. This will create a basic NIB file (they're called NIBs rather than XIBs for historical reasons). The first step in interface builder is to change the class name of the "File's Owner" to your UIViewController subclass (Test5ViewController). You can then drop anything that IB will allow into the view window or even replace the pre-supplied view object with one of your own. And here's the trick: make sure the view outlet (supplied by the UIViewController superclass) is connected to a view. Once this is done, this view will be automatically loaded when your NIB is loaded. You can then just put your UIViewController subclass (Test5ViewController) in your MainWindow.xib NIB file to get it automatically loaded, and you're in business.
Now, the way you're doing it here is the second way. Some people like to code this way all the time and not user interface builder. And while it's definitely necessary sometimes and always more flexible, it makes you understand what is happening a bit better. There may be other things, but the main thing you're missing is that in your code above, you have nothing that is adding your view into the view hierarchy. You need to check first that you have an UIApplicationDelegate subclass and it needs to load your "root" UIViewController class. All initial project creation types in xcode do this (except Window-based application). It is code like:
[window addSubview:rootController.view];
Once this is done, if your view controller wasn't loaded by the NIB (described briefly above), your loadView method will be called, expecting you to build your own view hierarchy. Above, you created the view(s), but failed to put them in a hierarchy. You need something like:
[self.view addSubview:curImage.view];
No view will be rendered until added to the view hierarchy. Make sure to look up the UIView class in the documentation and understand the variety of ways to add and remove views to the view hierarchy.
A couple things I should warn you about:
* your code above is leaking. You need to review how objective-C properties work. There's lots on this site about it. More than I have time to write about here.
* don't create a rootView property in the case you have here. There already is one in the superclass (UIViewController). It's just 'view'. Use that for saving your root view.
I hope this helps you get started. It can be bewildering at first, but you'll soon get it going! I recommend building and rewriting and rebuilding a lot of sample code before you do your "real" application. The SDK has many great samples.