What does the "Couldn't compile connection:" error mean?

Question

I'm getting the following error from Xcode:

Couldn't compile connection: <IBCocoaTouchOutletConnection:0x401538380 <IBProxyObject: 0x40154a260> => categoryPicker => <IBUIPickerView: 0x4016de1e0>> 

I've narrowed this down to a single outlet connection in storyboard. My code (about 30 views with lots of other connections) compiles and runs fine until I add a connection from a UIPicker to the view's categoryPicker property. The picker itself also works fine, I just can't reload it without getting this connection to work:

@interface FiltersTableViewController : UITableViewController <UIPickerViewDataSource, UIPickerViewDelegate> {     NSFetchedResultsController *fetchedResultsController;     FilterTableViewController *filterView;      AppDelegate *appDelegate;     NSManagedObjectContext *managedObjectContext;        }  @property (nonatomic, strong) FilterTableViewController *filterView; @property (nonatomic, strong) NSFetchedResultsController *fetchedResultsController; @property (nonatomic, strong) NSManagedObjectContext *managedObjectContext;  @property (nonatomic, weak) IBOutlet UIPickerView *categoryPicker;  - (void)configureCell:(FilterTableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath; - (void)performFetch;  @end 

The UIPickerView is in a UITableViewCell. Here's an image of the storyboard, the connection from "categoryPicker" to "FiltersTableViewController" causes the error:

Thanks for any ideas, or suggestions on how to debug it!

EDIT: I removed the connection and added one line to numberOfComponentsInPickerView:

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {      categoryPicker = pickerView;      return 1; 

}

This now works!, but I'd like to understand why the connection won't work and what that error message means. Right now this seems like a kludge to me since I use IB connections everywhere else to get object references.

EDIT 2: Connecting a prototype cell generates this error: Illegal Configuration: Connection "Cell" cannot have a prototype object as its destination. Not sure if this is new in Xcode 4.5.

Answer 1

SWIFT 2

I was creating a popover segue and I was getting the same error.

What I did was follow @matt's answer by not putting it on a cell, which is logical now that he explained it!

Instead, I put the TableView as the anchor and it worked fine.

Hope that helps those in the future.

Answer 2

The problem is that this is a prototype cell. It is meaningless to have an outlet to something in it, because it isn't a real cell: it's a model for what might be dozens or hundreds of cells, and which one would the outlet point to in that case?