I have a form in my Cocoa app that contains an NSSegmentedControl that I want to be controllable via the keyboard. It seems that NSSegmentedControl is very reluctant to become the first responder, however.
Setting the initial first responder of the window to the segmented control does nothing -- it will not have keyboard focus when the window is first loaded. It does receive focus if I manually set the first responder like this, however:
[segmentedControl.window makeFirstResponder: segmentedControl];
That will work fine if the only part of the form is the segmented control. If I add another field (say, an NSTextField), and I set the nextResponder of the segmented control to that field, the segmented control will never become first responder. Focus will immediately go to the text field, and pressing tab to switch back to the segmented control doesn't work.
I've tried subclassing NSSegmentedControl and overriding acceptsFirstResponder, becomeFirstResponder, etc. to no avail. The only one that makes any difference is resignFirstResponder -- if I return NO from that method then the segmented control will indeed retain focus, but obviously I don't want it to retain focus all the time.
Any ideas on how to get the control to behave like a normal responder?
It's behaving as intended. Not all controls participate in the "key view loop". Full keyboard navigation is turned on through Universal Access in System Preferences for all apps and it's not for individual apps to implement on their own.
It's best not to use a segmented control in a form intended for heavy keyboard entry. NSPopUpButton works more closely to what we all exepect in a web form so it's not as if it's necessarily the wrong choice in your app's UI.
Rather than answer exactly the question you asked (which someone else can do), I humbly suggest you choose on the side of functionality at the cost of a slightly prettier UI element since that prettier UI element wasn't intended to get along with the keyboard.