如何使用纸张的返回值来决定是否要关闭窗口？

Question

我想用windowShouldClose:在我的NSWindowController子类弹出一个表，询问用户是否希望与保存在关闭之前保存更改，取消，不保存按钮。

我运行到是beginSheetModalForWindow:...问题使用委托，而不是一个返回值的。

我可以在windowShouldClose:返回NO，但然后当我发送[self close]到面板中的委托没什么控制器发生。

有人能向我解释如何做到这一点或点我的一些示例代码的方向？

Answer 1

的基本解决方案是将一个布尔标志，指出该窗口是否已经警告未保存的更改在窗口上。主叫[自紧密]之前，该标志设置为真。

最后，在windowShouldClose方法，返回该标志的值。

Answer 2

这是我最后使用的代码。

windowShouldCloseAfterSaveSheet_是在我的控制器类的一个实例变量。

记住设置窗口出口，用于在IB控制器。

- (BOOL)windowShouldClose:(id)window {    
  if (windowShouldCloseAfterSaveSheet_) {
    // User has already gone through save sheet and choosen to close the window
    windowShouldCloseAfterSaveSheet_ = NO; // Reset value just in case
    return YES;
  }

  if ([properties_ settingsChanged]) {
    NSAlert *saveAlert = [[NSAlert alloc] init];
    [saveAlert addButtonWithTitle:@"OK"];
    [saveAlert addButtonWithTitle:@"Cancel"];
    [saveAlert addButtonWithTitle:@"Don't Save"];
    [saveAlert setMessageText:@"Save changes to preferences?"];
    [saveAlert setInformativeText:@"If you don't save the changes, they will be lost"];
    [saveAlert beginSheetModalForWindow:window
                                modalDelegate:self
                               didEndSelector:@selector(alertDidEnd:returnCode:contextInfo:) 
                                  contextInfo:nil];

    return NO;
  }

  // Settings haven't been changed.
  return YES;
}

// This is the method that gets called when a user selected a choice from the
// do you want to save preferences sheet.
- (void)alertDidEnd:(NSAlert *)alert 
         returnCode:(int)returnCode
        contextInfo:(void *)contextInfo {
  switch (returnCode) {
    case NSAlertFirstButtonReturn:
      // Save button
      if (![properties_ saveToFile]) {
        NSAlert *saveFailedAlert = [NSAlert alertWithMessageText:@"Save Failed"
                                                   defaultButton:@"OK"
                                                 alternateButton:nil
                                                     otherButton:nil
                                       informativeTextWithFormat:@"Failed to save preferences to disk"];
        [saveFailedAlert runModal];
      }
      [[alert window] orderOut:self];
      windowShouldCloseAfterSaveSheet_ = YES;
      [[self window] performClose:self];
      break;
    case NSAlertSecondButtonReturn:
      // Cancel button
      // Do nothing
      break;
    case NSAlertThirdButtonReturn:
      // Don't Save button
      [[alert window] orderOut:self];
      windowShouldCloseAfterSaveSheet_ = YES;
      [[self window] performClose:self];
      break;
    default:
      NSAssert1(NO, @"Unknown button return: %i", returnCode);
      break;
  }
}