Toggle-style button : how to toggle title in this case?

I have a CoreData app presenting data with a TableView, textfields, buttons... It deals with people situations and one of the button is a toggle-style button with title "Close". When we consider the user's case closed, we press and it changes the state of a boolean-type attribute in the entity, representing the closed/open state of the case, using a simple binding to the attribute value. The button title also becomes "Reopen" as the case may be reopened in the future.

Then additional things had to be done with the data on pressing the button, so I had to create an IBAction method instead of simply use the former binding. Problem: when button is pressed, the action is done, but the button title is not toggled. It makes sense since nothing tells it to toggle anymore.

I decided to remove the action on the boolean from the IBAction and use again the value binding, so the boolean change is performed by the binding and the other operations are performed by the IBAction. Problem: it modifies the data unexpectedly, sometimes working fine, sometimes not doing all things in a coherent way as expected.

So I'm back with all changes handled by the IBAction and this time, I'm using the开发者_开发技巧 Title/Alternate title bindings instead of the value binding. Now the button title toggles, but instead of displaying the word "Close" and "Reopen", it displays the boolean values "0" and "1".

I should perhaps handle the button title change in the IBAction as well, using "setTitle", but then I see a new problem coming. On app start-up, how will it pick the appropriate entity record for reference? And what if the table is in a "No Selection" situation? Looks like a quite extensive piece of code to handle such a small issue...

Any advice on a short, more direct way of handling this is welcome. Thanks.

Sounds like you probably have a couple of different options.

This first option is a bit more involved than the others, but is still good to know for the record. This option basically would not use bindings for the close/re-open button, but instead, set the title, etc. programmatically. The basic game plan would be as follows:

• The close/re-open button's initial title when the document opens is set in the nib file (e.g. Close).

• Optionally, when the document opens, you could disable the button in -awakeFromNib, since the table view will have no initial selection.

• The only actions that would necessitate the button's title or enabled state to be changed is 1) when the tableview's selection is changed, and 2) when you've clicked the close/re-open button to toggle the case's state.

To achieve the desired result, you'd create an IBOutlet to the close/re-open button if you don't already have one. You'd then connect up the tableview's delegate outlet to your controller class, which will let your controller class know when the tableview's selection has been changed (via the - (void)tableViewSelectionDidChange:(NSNotification *)notification <NSTableViewDelegate> protocol method). You would also need to update the close/reopen IBAction method to make sure it switches the title on the button after being clicked (since the tableview selection wouldn't change during that operation). The controller class's code might look something like this:

// add this declaration to avoid compiler warnings:
@interface LHController (LHPrivate)
- (void)updateCloseReopenButtonTitle;
@end

- (void)awakeFromNib {
   [self updateCloseReopenButtonTitle];
}

- (void)tableViewSelectionDidChange:(NSNotification *)notification {
   [self updateCloseReopenButtonTitle];
}

- (IBAction)toggleCloseReopenButton:(id)sender {
    // do your existing code here and then add:
   [self updateCloseReopenButtonTitle];
}

- (void)updateCloseReopenButtonTitle {
    // assuming 'casesController' is an IBOutlet to your NSArrayController
    NSArray *selectedObjects = [casesController selectedObjects];
    // loop through the selected cases to determine whether
    // they're all closed, all open, or mixed to set
    // the title of the button appropriately
    BOOL allClosed = YES;
    for (LHCase *case in selectedCases) {
        if ([case isOpen]) {
           allClosed = NO;
           break;
        }
    }
    [closeReopenButton setTitle:(allClosed ? @"Reopen" : @"Close")];
    [closeReopenButton setEnabled:[selectedObjects count] > 0];
}

Before bindings came along, this is how we used to have to do things.

Another option might be reconsidering your user interface: maybe rather than a push/toggle button whose title you need to toggle, you could instead just have a checkbox titled Closed, which would signify whether the selected cases were closed or not. You could use bindings for the checkbox's state, like shown in the image below:

You could then have an IBAction method that handles the extra stuff that needs processing. You can ask the casesController for the -selectedObjects and then loop through them. As long as you make sure the checkbox Allows Mixed states, it has the added advantage of better representing mixed-case scenarios, in case of a selection of cases with mixed open/closed states (the checkbox a dash instead of a full check).

Another option if you want to stick with a toggle button is to create and specify a custom NSValueTransformer for the title and alternate title bindings. This value transformer would take in the boolean closed/open state of the case and turn it into a string more fitting than just 0 or 1 (which is what's being displayed now). It might look something like this:

+ (Class)transformedValueClass {
    return [NSString class];
}

+ (BOOL)allowsReverseTransformation {
    return NO;
}

- (id)transformedValue:(id)value {
    BOOL isClosed;

    if (value == nil) return nil;

    // Attempt to get a reasonable value from the
    // value object.
    if ([value respondsToSelector: @selector(boolValue)]) {
        isClosed = [value boolValue];
    } else {
        [NSException raise: NSInternalInconsistencyException
                    format: @"Value (%@) does not respond to -boolValue.",
        [value class]];
    }
    return (isClosed ? @"Reopen" : @"Close");
}