Re: previous value of NSControl

FROM : Jens Alfke
DATE : Sat Mar 15 06:27:10 2008

On 14 Mar '08, at 6:20 PM, norio ota wrote:

> I set an action to a NSDatePicker and I'd like to know if an input 
> value , especially year component, is different from the year of its 
> previous date in the action method, without having a placeholder for 
> the previous value.


Use key-value observing (KVO). You can configure it to tell you the 
old as well as the new value.
It's all described in great detail in the documentation; read it 
carefully, because it gets quite tricky, though. For just this one 
case, it might be simpler just to store the previous value in an 
instance variable...

—Jens