I've got a strange problem here.
I have a class that I'll call MainView. In MainView I have one NSImageView, which I'll call imageView. I've hooked this up to an image view through Interface Builder. I've also initialized an instance of MainView in Interface Builder, and have connected an outlet to that instance to another class with an ivar name of mainView. So then, I access the image view like this:
[mainView imageView]
So then, for a test I NSLog'd the imageView and it returned the address of the objet. So far so good.
Here's the problem: now I'm trying to get the origin of that imageView by doing this:
NSPoint point = [[mainView imageView] frame].origin;
This should work, right? I'm getting an EXC_BAD_ACCESS (also got a SIGABRT once) warning here with the error in console of: -[NSImage frame]: unrecognized selector sent to instance 0x1001d5fd0
The strange part is that this always used work just fine, but I changed some ivar names and it seemed to mess up the whole thing. I almost know for certain it's not a hookup issue with IB because I get a memory address when I log the object. Any ideas?
The error message
-[NSImage frame]: unrecognized selector sent to instance 0x1001d5fd0
means that imageView is pointing to an NSImage object instead of an NSImageView object. It looks like somewhere in your code you’re reassigning the imageView outlet, making it point to an NSImage instance.
Related
So I'm new to objective c, practically new to programming in general.
Anyway, in my simple program, I control-dragged my UITextField from the storyboard into my ViewController.m thinking it was a way to create a method to be invoked when the field was entered/tapped on. It wasn't long until I deleted the method.
When running the simulator, the keyboard would come up and the text field would already be focused on. If I tapped anywhere else on the screen, it resulted in a crash giving me the unrecognized selector error for the selector I already deleted.
There's nothing in my ViewController.h and the rest of the code seems fine. If I re-add the selector with no instructions, it behaves as intended and the keyboard resigns. My question is, why am I getting this error?
It would be more helpful to have the output of the crash. With that said I suspect your storyboard still has an outlet hooked up, referencing the function or outlet you created. From your storyboard click on your textfield and then navigate to the connections inspector (view -> utilities -> connections inspector). From there you should be able to see any connections you have made. Click the x to get rid of it.
The connection inspector is the icon in the upper right with the right facing arrow inside of a circle.
Edit:
I realized you asked why this is happening and not how to fix it. Unrecognized selector means just what it sounds like. Your code, in this case the storyboard is trying to call a method or access a variable on an object that doesn't implement that method. Normally the compiler catches these types of errors in your code but there are cases it can't catch, like the one your experiencing. For example it is ok to assign an NSArray object to a variable declared as something else, say an NSString as follows
id object = #[#"hello", #"world"];
NSString *notAString = object;
[notAString length];
Try running this and it will crash with a similar error because NSArray implement the length method, or in Objective-c speak, it doesn't respond to the selector "length".
Most typically it's this:
Select your UITextField in IB, go to the Connections inspector and remove the ghost connection to the removed method.
For some reason I'm having a very difficult time wiring my NSToolbarItem to an IBAction.
I'm using an NSWindowController with its own XIB. The NSToolbar is dropped into the XIB, and I added the NSToolbarItem without issue. This whole NSWindowController is created by a master NSViewController when an image is clicked.
The problem lies with the new button not sending. I unchecked "Autovalidates" and checked "Selectable" so that I could actually click the button.
However when pressed, I receive "unrecognized selector sent to instance".
I've wired this several times over through the XIB interface to make sure I wasn't messing up.
What's going on? Thank you.
Full error:
-[__NSCFType buttonPressed:]: unrecognized selector sent to instance 0x101915010
The delegate class does not know the selector you've wired. Either your delegate is wrong or you've got a typing error in your method.
Check the signature of the Method you've declared in your headerfile vs. its implementation in the class file. Perhaps you forgot to declare a parameter.
edit:
the class type where the selector is called looked weird, so I googled __nscftype unrecognized selector. here are some suggestions, it seems like your delegate is already disposed :
http://imlocation.wordpress.com/2007/09/13/strange-objects-nscftype-indicate-memory-management-bugs/
[__NSCFType searchKeyword:]: unrecognized selector sent to instance 0x6d8eb80
I've got a relatively simple problem that's been evading solution for some time. I have a view controller and an associated XIB. The view controller is called FooterViewController. FooterViewController's view is set as the footer view of a tableview.
FooterViewController's view includes a label for showing feedback to the user. I would like this label to persist until its value is changed by my application. Under normal circumstances, it does. However, I've just begun testing with memory warnings, and I've found that after the view is unloaded in response to a memory warning, the label is cleared.
Here's what I've tried so far to solve the problem: in FooterViewController's viewWillUnload method, I store the label's text in an instance variable called statusString:
- (void)viewWillUnload
{
statusString = [statusLabel text];
testInt = 5;
NSLog(#"View will unload; status string = %#; testInt = %d",
statusString, testInt);
[super viewWillUnload];
}
Note that I've also set another instance variable, declared as NSInteger testInt, to 5.
Then, in FooterViewController's viewDidLoad method, I try to set the label's text to statusString:
- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(#"Just before setting label, statusString: %#; testInt: %d",
statusString, testInt);
[statusLabel setText:statusString];
NSLog(#"View did load.");
}
However, this does not work. Further, in the log after simulating a memory warning, I see:
View will unload; status string = Invalid IP address Error code: 113; testInt = 5
(Note that "Invalid IP address Error code: 113" is the correct value for statusString)
Then, after navigating to FooterViewController again, I see:
Just before setting label, statusString: (null); testInt: 0
This indicates to me that for some reason, the instance variables of FooterViewController are being reinitialized when the view loads again. A final note: the method initWithNibName:bundle: is being called each time the view must reload, though I expect this; after all, the view must be reloaded from the NIB.
So, my questions are these:
Why do these instance variables appear to be nullified or zeroed in the process of unloading and reloading the view?
If I'm doing something incorrectly that's causing this nullification, what is it?
If I'm not doing anything incorrectly, and this is normal behavior, how should I handle maintaining state between loads of the view?
Thanks,
Riley
The statusString looks like a weak reference, not a strong property. It can not retain the labels's text, which gets deallocated with the label when the view is unloaded. That's why you get first a correct value (before the label is deallocated), and null later (after the label has been deallocated, and the weak ref nullified). Turn your statusString into a strong property, and that ARC magic won't bite you any longer.
It looks like you need to be using didRecieveMemoryWarning instead of viewDidUnload, since viewDidUnload is not guaranteed to be called in the event of a memory warning. If the crash is exiting the app completely then you need to be writing the data to disk using something like coreData. Save your data here and then call the super so the view will still be released. Hope that helps.
I figured out what was going on, finally. The issue was that I called the allocation and initialization methods for FooterViewController in its parent view controller's viewDidLoad method. When the views were dumped and subsequently reloaded, my view controller was re-initialized! This destroyed the original FooterViewController, which maintained the instance variables I needed, and replaced it with a brand-new VC.
The solution was to move [[FooterViewController alloc] init] to the init method of FooterViewController's parent VC, so that the initialization was only performed once per run cycle.
I've learned my lesson: don't reinitialize your view controllers unless you really mean to do so. As such, be very careful where you put your calls to the initializer in parent view controllers.
Thanks for the help I got from the two answerers.
Warning: complete newbie Xcode question.
In MainViewController.h I have the following line:
IBOutlet WorkItem *m_WIone;
I have created a class called WorkItem which is inherited from UILabel. The line above is so that I can use m_WIone (which will eventually become an array of such objects) as a member variable throughout MainViewController.
I have tried various ways to call WorkItem methods and finally settled on:
[m_WIone Reset];
where Reset is a WorkItem method. The method is declared in WorkItem.h as:
-(void) Reset;
and in WorkItem.m as:
-(void) Reset {}
With or without contents in this method, the app always crashes with:
Thread 1: Program received signal: "SIGABRT".
In the logging, I read:
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UILabel Reset]: unrecognized selector sent to instance 0x6a5f9f0'
How can I solve this? Am I even declaring this member variable correctly? (Despite trawling through StackOverflow, I cannot find the solution.)
Did you specify your custom class for the NIB? It seems like you want a widget in XCode's Interface Builder to use your custom class. Only the default class (UILabel) would be instantiated instead of your custom class.
Click on the UILabel you're using as the outlet and change the class (the screenshot here is for UITableView, but it should work the same for UILabel).
With that being said, there are alternatives to what you're trying to do. Instead of just using UILabel (which you eventually plan to make an array of them). Why not use a UITableView and customize cells to what you see fit (since UITableViews optimal for displaying lists of items)?
I'm having trouble with a cocoa project. I'm displaying a keyboard composed of NSButtons, and I'd like that when I click on one of the keys, the label is added to a NSTextField. I have a controller that I use as a singleton, so each key "knows" how to access the controller. In the controller, I have an outlet linked to the NSTextField. When I click on a key, nothing happens. So I used something like NSLog(#"%#", [[[OakController] sharedInstance] textarea]) on a mouseDown event, and in the console output, I get (null).
Long story short, my outlet is set to nil, and I don't know why it is that way, or how to solve that...
Here's the code of the controller : https://gist.github.com/1090564. Sorry for the lack of syntax coloring.
Thanks for reading guys!
My guess is that you actually have multiple instances of OakController instead of one like you expect. Did you drag a blue cube into your IB document and change its custom class to OakController? That will allocate and initialize a new object each time. I'd guess that your sharedInstance method also allocates and initializes an instance.
Try adding an awakeFromNib method to OakController, and add a break point. Log self's pointer value. In your second case were the outlet is unexpectedly nil, also log self's pointer address.