On Mar 24, 2009, at 3:54 AM, Michele Barboni wrote:
On Mar 19, 2009, at 10:11 AM, Michele Barboni wrote:
Hi,
I've a NSSegmentedControl, 7 segments (labeled with weekdays),
which has selectedIndex bound through a value transformer (NO
reverse transformation) to NSDates.
Now, one of my awakeFromNib do this:
[sedutaDays setTarget:self];
[sedutaDays setAction:@selector(setWeekDay:)];
[sedutaDays setContinuous:YES];
setWeekDay: essentially change the day of the NSDate which
NSSegmentedControl is bound to, by accessing the NSArrayController,
selectedObjects:, objectAtIndex:0, and so on..
The problem is that my setWeekDay: action is sent only if I click
the selected segment (set by binding), clicking on any of other 6
segments results in an attempt to reverse transform the value,
which obviously fail with "[NSCFNumber
timeIntervalSinceReferenceDate]: unrecognized selector sent to
instance 0x1019a40" since my value transformer doesn't reverse..
Any idea why it seems that only selected segments has setAction: ?
Passed two last days trying to understand why my NSSegmentedControl
has this behavior but nothing came out.. I'm very disappointed..
It is not the behavior of the NSSegmentedControl, but bindings that
you are not understanding. The binding is not trying to reverse
transform , or you would get a different error message--assuming that
your transformer is properly implemented, that is.
Refer to:
http://developer.apple.com/documentation/Cocoa/Conceptual/CocoaBindings/Concepts/MessageFlow.html#/
/apple_ref/doc/uid/TP40002149-186285
If your transformer does not support reverse transformations, then
your setter method must assume that it is receiving a transformed
value--in this case, an NSNumber. Does it make this assumption?
Note that the segment control would have sent your action method if
you didn't get the exception first. Selecting the currently selected
segment works because you are not changing the bound value, which is
precipitating the exception.
HTH,
Keary Suska
Esoteritech, Inc.
"Demystifying technology for your home or business"
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