Overview

An SPViewController controls and displays a Sparrow display tree. It represents the main link between UIKit and Sparrow.

The class acts just like a conventional view controller of UIKit. It extends GLKViewController, setting up a GLKView object that Sparrow can render into.

To initialize the Sparrow display tree, call the ‘startWithRoot:’ method (or a variant) with the class that should act as the root object of your game. As soon as OpenGL is set up, an instance of that class will be created and your game will start. In this sample, Game is a subclass of SPSprite that sets up the display tree of your app:

[viewController startWithRoot:[Game class]];

If you need to pass certain information to your game, you can make use of the onRootCreated callback:

viewController.onRootCreated = ^(Game *game)
{
    // access your game instance here
};

Resolution Handling

Just like in other UIKit apps, the size of the visible area (in Sparrow, the stage size) is given in points. Those values will always equal the non-retina resolution of the current device.

Per default, Sparrow is started with support for retina displays, which means that it will automatically use the optimal available screen resolution and will load retina versions of your textures (files with the @2x prefix) on a suitable device.

To simplify the creation of universal apps, Sparrow can double the size of all objects on the iPad, effectively turning it into the retina version of an (imaginary) phone with a resolution of 384x512 pixels. That will be your stage size then, and iPads 1+2 will load @2x versions of your textures. Retina iPads will use a new suffix instead: @4x.

If you want this to happen (again: only useful for universal apps), enable the doubleOnPad parameter of the start: method. Otherwise, Sparrow will work just like other UIKit apps, using a stage size of 768x1024 on the iPad.

Render Settings

Some of the basic render settings are controlled by the base class, GLKViewController:

• Set the desired framerate through the preferredFramesPerSecond property
• Pause or restart Sparrow through the paused property

Accessing the current controller

As a convenience, you can access the view controller through a static method on the Sparrow class:

SPViewController *controller = Sparrow.currentController;

Since the view controller contains pointers to the stage, root, and juggler, you can easily access those objects that way.