iPad SDK : Popovers - The Font Name Popover (part 2)

2. The Back End

Now it's time to implement the portions of DudelViewController that will fire up the FontListController, dismiss its popover when the user makes a selection, and grab the selected value. Start with an import:

#import "FontListController.h"

Then fill in this previously empty method:

- (IBAction)popoverFontName:(id)sender {
  FontListController *flc = [[[FontListController alloc]
      initWithStyle:UITableViewStylePlain] autorelease];
  flc.selectedFontName = self.font.fontName;
  [self setupNewPopoverControllerForViewController:flc];
  flc.container = self.currentPopover;
  [[NSNotificationCenter defaultCenter] addObserver:self
      selector:@selector(fontListControllerDidSelect:)
      name:FontListControllerDidSelect
      object:flc];
  [self.currentPopover presentPopoverFromBarButtonItem:sender
      permittedArrowDirections:UIPopoverArrowDirectionAny
      animated:YES];
}

This method creates and configures a FontListController instance. Part of the configuration involves calling a method named setupNewPopoverControllerForViewController: (which we're going to create in just a minute). It also sets us up as an observer for a notification, which will tell us that the user selected something, and then displays a popover.

What's not really clear here is the final line, which contains self.currentPopover. We haven't set that, have we? Well, the following auxiliary method does! Insert this method somewhere above all the popover action methods:

- (void)setupNewPopoverControllerForViewController:(UIViewController *)vc {
  if (self.currentPopover) {
    [self.currentPopover dismissPopoverAnimated:YES];
    [self handleDismissedPopoverController:self.currentPopover];
  }
  self.currentPopover = [[[UIPopoverController alloc] initWithContentViewController:vc]
    autorelease];
  self.currentPopover.delegate = self;
}

					  

We'll use this method every time we're going to present a popover. By doing so, we save a few lines in each popover action method, and also ensure that we're doing things the same way each time. Now, I'm not going to pretend that this separate method sprang from my forehead in one piece.

Any time you find yourself doing cut-and-paste coding, consider chunking things off into separate methods, because someone is probably going to revisit your code someday. The mind you save may be your own.

So now we have code in place to fire up the popover, but we still need to handle the user selecting something. Begin by creating a method to be called when the notification we're observing is triggered:

- (void)fontListControllerDidSelect:(NSNotification *)notification {
  FontListController *flc = [notification object];
  UIPopoverController *popoverController = flc.container;
  [popoverController dismissPopoverAnimated:YES];
  [self handleDismissedPopoverController:popoverController];
  self.currentPopover = nil;
}

Here, you see the reason for putting the container property in FontListController. After the user makes a selection, FontListController shoots off a notification. DudelViewController picks it up, and uses the container property to dismiss the popover. This method also calls the main handler for all our popovers, which you should now revise to this:

- (void)handleDismissedPopoverController:(UIPopoverController*)popoverController {
  if ([popoverController.contentViewController isMemberOfClass:
       [FontListController class]]) {
      // this is the font list, grab the new selection
    FontListController *flc = (FontListController *)
      popoverController.contentViewController;
      self.font = [UIFont fontWithName:flc.selectedFontName size:self.font.pointSize];
  }
  self.currentPopover = nil;
}

					  

This is where the selection in the popover finally ends up having an effect. The font is now set according to what the user picked.

You should now be able to build and run the app, and then touch the font list button in the toolbar to see something like the popup shown in Figure 2.

Try selecting a different font, and then using the Text tool to create some text. Neat! You now have the full complement of fonts included with the iPad at your disposal. You're still stuck with just one size, so let's tackle that next.

Figure 2. Selecting a font