NSComboBox action selector fires when setHidden:YES

Question

I have an NSComboBox. I've set an action selector. When the box gets hidden the selector fires, even if the user never touched it. Yes, I need to hide it.

IBOutlet NSComboBox *comboBox;

[comboBox setAction:@selector(onComboBoxSelection:)];

- (void)onComboBoxSelection:(id)sender
{
   NSLog(@"Why does this fire twice");
   //My code doesn't actually set hidden here, it's just for proof while debugging the issue.
   [comboBox setHidden:YES];
}

Why would hiding an NSControl fire it's selector? What's the best way to fix it?

Update: I've fixed it by wrapping the method. But I'd still like to understand why, or other ways to fix it.

- (void)onComboBoxSelection:(id)sender
{
   if(![sender isHidden]{
     NSLog(@"Now only fires once");
     //My code doesn't actually set hidden here, it's just for proof while debugging the issue.
     [comboBox setHidden:YES];
   }
}

Answer 1

Set a breakpoint in onComboBoxSelection: and look at the backtrace when it's called the second time (type bt in the debugger to see the backtrace). That will explain what's going.

A combo box is both a text field and a popup, and it will fire actions for both. The text field action is fired when editing ends, either by hitting the Return key or when it resigns first responder (e.g., tabbing out to another field).

When you hide the combo box, the text field resigns first responder and fires its action.

What you probably want to do is check if combo box value has actually changed, and only then proceed with hiding the combo box, etc.

Another option is to use data bindings to observe changes to the combo box. Bind the combo box value to a property on your controller. Then implement the property setter in your controller.

Answer 2

try this [comboBox setHidden:1];