The best way to apply a theme to an iPhone application

Question

Hi, I am trying to write an application for the iPhone using a theme switcher where users can select a theme to change the background color, alpha, image and some buttons and appearance (size, image or even location).

What would be the best way to apply the theme?

Thanks Tim

Answer 1

This is how I implemented the ability to change themes in FemCal. I have included some details in the form of code snippets.

• Create a singleton ThemeMgr class that stores colors, images, etc. Choose a singleton if necessary.

   @interface ThemeMgr : NSObject { // selected color and image NSString * selectedColor; NSString * selectedPicture; // dictionaries for color and image NSDictionary * colorData; NSDictionary * imageData; NSDictionary * backgroundData; // names NSArray * colors; NSArray * images; // themes UIColor * tintColor; UIImageView * panelTheme; UIColor * tableBackground; } 

• Use notifications to broadcast theme changes. As a notification, I used @ThemeChange.

   - (void)fireTimer:(NSTimer *)timer { NSNotification * themeChange = [NSNotification notificationWithName:@"ThemeChange" object:nil]; [[NSNotificationQueue defaultQueue] enqueueNotification:themeChange postingStyle:NSPostWhenIdle]; } 

  Obviously, you will have some user interface to select the theme you want. In this case, the user selects a theme, and fireTimer starts after 0.5 seconds. This gives a good delay for updating another user interface before I force the user interface to redraw itself.

• Listen to notifications wherever you need to act when a topic changes.

   // listen for change notification [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(updateAppearance:) name:@"ThemeChange" object:nil]; 

  I only have a few views, so I wrote the code in every controller that I use, but you can use the objective-C power to mix the code to better control this way.

• Embed the code to actually redraw your presentation based on the theme.

   - (void)updateAppearance:(NSNotification *)notification { // background for grouped table view ThemeMgr * themeMgr = [ThemeMgr defaultMgr]; // change color and reload [self.tableView setBackgroundColor:[themeMgr tableBackground]]; [self.tableView reloadData]; self.navigationController.navigationBar.tintColor = [themeMgr tintColor]; } 

Do not forget to cancel any notifications when necessary, and you will have to write code in viewDidLoad or similarly apply any themes before the view is displayed.

Answer 2

I have no answers. I implemented it using events and singleton. Basically, the singleton installation object sends changes to observers who update the GUI on events. I remember that there is a way in which you can listen to the change of the instance variable, but forgot how to do it. My current way works for me very well.