El 28/06/2008, a las 0:23, Keary Suska escribió:
6/27/08 4:06 PM, also sprach [EMAIL PROTECTED]:
I am struck in what should be a simple task so I would appreciate any
help.
I have a menu item which I want to show a default on or off state, so
I set up a binding in IB to a BOOL "monitor" property in my
controller. This works ok and both the check mark in the menu item
and
the property are kept in sync whatever I change.
However, the menu item I am talking about is intended to trigger an
action that can fail, so I want to keep its ultimate state unchanged
in some cases. For this purpose I added an action method that checks
the original state of the menuState property and resets it
accordingly
depending on the success status of the performed accion.
The code looks as follows
- (BOOL)menuState { return menuState ; }
- (void)setMenuState:(BOOL)value
{
NSLog(@"setMenuState (%d) called",value);
menuState = value ;
}
- (IBAction) myAction:(id)sender
{
do something...
if ( fail ) [self setMenuState:NO] ;
}
I observed that when the user clicks on the menu item the action
method is called before any change is made to menuState, but then
setMenuState may be called twice: one from myAction (if it fails) and
one from the frameworks. The problem here is that after the second
call both menuState and the menuItem no longer shows the intended
state.
When using bindings always stick to MVC--i.e., don't touch the menu.
If you
have to change the state, change the "monitor" value to reflect the
correct
state. IN any case, you don't say how the menuState property enters
into the
picture, vs the "monitor" property.
In fact "monitor" is meant to be the same as "menuState", Sorry, it
was a typo since I was trying to use more understandable names for the
dev-list. In the real app I am using "monitor" as the name of the
variable but I thought "menuState" would be more a appropriate name
for discussion here. So let's forget "monitor" ;) "menuState" is the
model property that is binded to the menuItem value.
As you suggest, I actually do stick to MVC and KVC, so I only change
the menuItem state through the model "menuState" property as shown in
the "myAction" method.
The problem remains because when the user selects the menuItem the
following happens:
FIRST- myAction is executed (possibly setting menuState to an
appropiate value)
SECOND - setMenuState is executed with a value contrary to the last
one, so if I had set it to NO in myAction, it is called now with YES,
destroying completely the intended behaviour. The menu item then shows
the wrong state in the running app.
I thought that I could get rid of the myAction method and observe the
menuState property instead, but the whole problem still would remain
because I still want to be able to set "menuState" to an appropriate
state while observing it. Finally I could use some flag variable to
tell me whether the setMenuState call comes from the menuItem click or
from my own code, but that seems rather weird to me and I believe that
there should be a cleaner way.
Any help is appreciated.
Joan Lluch
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