Re: Using alerts with Preference Panes

FROM : Pete Gontier
DATE : Thu Dec 16 18:22:38 2004

circa Thu, 8 May 2003 18:54:23 +0200 (MEST), Andreas Schempp wrote:

>> I'm creating a preference pane, and I need an alert to show up if user
>> information was incorrectly supplied. I tried using the NSBeginAlertSheet
>> with my sample application and it worked fine, but when I moved the code over
>> to my preference pane, the compiler did not seem to recognize my NSWindow
>> (_window or a new outlet for window).


> You can't attach the alert panel to your window, because System
> Preferences.app takes the view from your window and attaches it to it's own.
> Use [NSApp mainWindow]. This works.


Unfortunately, it did not make any difference for me. I too am attempting to
post sheets onto the System Preferences window. I have a view in the window
which I keep track of only so that I can call its window method to get a
value I can pass to sheet-oriented methods. When I pass this value to the
beginSheetForDirectory method of NSSavePanel or NSOpenPanel, everything
works fine. However, when I pass this value to NSBeginAlertSheet, some truly
weird stuff happens. I get a stand-alone alert instead of a sheet, and the
System Preferences window disappears. I think the window is being hidden;
selecting it from the Windows menu shows it again. Below please find an
excerpt from the code. Note the first GOTTEN/USED sequence works but the
second does not.

- (void) onNotificationSavePresetIntoFile : (NSDictionary *) messageEnvelope
{
    // blah blah blah

    NSWindow * window = [fTabs window];                    // ***** GOTTEN
    Assert (window);

    NSSavePanel * savePanel = [NSSavePanel savePanel];
    Assert (savePanel);

    // blah blah blah

    [savePanel  beginSheetForDirectory : nil
                file                  : presetName
                modalForWindow        : window            // ***** USED
                modalDelegate          : self
                didEndSelector        :
                    @selector (savePreset:returnCode:contextInfo:)
                contextInfo            : [presetData retain]        ];
};

- (void) savePreset    : (NSSavePanel *) sheet
        returnCode    : (int) returnCode
        contextInfo    : (NSData *) contextInfo
{
    @try
    {
        // blah blah blah
    }
    @catch (NSException * exception)
    {
        [exception spawnAlertSheetInto : [fTabs window]    // ***** GOTTEN
            modalDelegate : self];
    }
}

- (void) spawnAlertSheetInto    : (NSWindow *) parentWindow
        modalDelegate          : (id) modalDelegate
{
    // blah blah blah

    SpawnLocalizedAlertSheet
        (parentWindow,modalDelegate,name,reason,nil,nil,nil,nil);
}

static void SpawnLocalizedAlertSheet (  NSWindow *    window,
                                        id            modalDelegate,
                                        NSString *    title,
                                        NSString *    message,
                                        NSString *    defaultButton,
                                        NSString *    alternateButton,
                                        NSString *    otherButton,
                                        SEL            actionSelector    )
{
    // blah blah blah

    NSBeginAlertSheet (    localizedTitle,
                            localizedButtonDefault,
                            localizedButtonAlternate,
                            localizedButtonOther,
                            window,                        // ***** USED
                            modalDelegate,
                            nil,
                            actionSelector,
                            nil,
                            localizedMessage        );
}

  --

    Pete Gontier
    http://www.m-audio.com/