Hi list,
I'm setting up a binding using an NSController, which I want to connect the
currently selected row in a table to the values of some UI controls. Put
another way, whenever the table's selected row changes, the binding should
cause some controls to display new information pulled from the row.
It's not working, but the error I'm seeing makes no sense. I've switched to
using tableViewSelectionDidChange in a delegate, and that works perfectly. I'm
not desperate to solve this problem since my delegate does what I want; I'm
more curious about why it might be happening.
The key for the binding is my view controller .currentTweet. That property is
computed, and I've marked it as dynamic and implemented keyPathsForValues. Yet,
when I run it with the binding in place: "fatal error: unexpectedly got nil
while unwrapping an optional value." The weird part: nowhere on the line in
question do I use an optional. Here are two declarations. The first is where
the second gets its value; the second is what my controller is bound to. Both
of these happen in my ViewController subclass, outside of any methods.
dynamic var currentTweet:Tweet? {
get {
return currentTab.tweetsList[tweetsTable.selectedRow]
//Xcode points to this line as the problem
}
}
dynamic var currentTweetID:String? {
get {
if let tempTweet=currentTweet, tempID =
tempTweet.idAsString {
return tempID
}
return nil
}
}
Yes, both properties are optional, but the line Xcode is complaining about has
no optionals at all. My only thought is that this binding is happening before
the table is created, thus tweetsTable.selectedRow has no value? I thought
about putting the tweetsTable.selectedRow bit in an 'if let', but that won't
work because it's not optional so Swift won't let it in an 'if let'.
As I said, I'm just curious about this, not desperate to fix it and totally
lost like a couple weeks back. :) My delegate does a fine job doing what I
want, and I might never use a binding for this job at all. The error is just
such an odd one, considering there are no optionals on that line.
--
Have a great day,
Alex Hall
mehg...@icloud.com
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