GLKViewController Class Reference

Inherits from
Conforms to
Framework
/System/Library/Frameworks/GLKit.framework
Availability
Available in iOS 5.0 and later.
Declared in
GLKViewController.h
Related sample code

Overview

The GLKViewController class provides all of the standard view controller functionality, but additionally implements an OpenGL ES rendering loop. A GLKViewController object works in conjunction with a GLKView object to display frames of animation in the view.

To use this class, allocate and initialize a new GLKViewController subclass and set its view property to point to a GLKView object. Then, configure the view controller’s preferredFramesPerSecond property to the desired frame rate your application requires. You can set a delegate or configure other properties on the view controller, such as whether the animation loop is automatically paused or resumed when the application moves into the background.

When active, rendering loop automatically updates the view’s contents each time a new frame must be displayed. Each frame is rendered by the view controller using these steps:

  1. The view controller calls its delegate’s glkViewControllerUpdate: method. Your delegate should update frame data that does not involve rendering the results to the screen.

  2. The view controller calls its view’s display method. Your view should redraw the frame.

Subclassing Notes

Your application should subclass GLKViewController and override the viewDidLoad and viewDidUnload methods. Your viewDidLoad method should set up your context and any drawable properties and can perform other resource allocation and initialization. Similarly, your class’s viewDidUnload method should delete the drawable object and free any unneeded resources.

As an alternative to implementing a glkViewControllerUpdate: method in a delegate, your subclass can provide an update method instead. The method must have the following signature:

- (void)update;

Tasks

Configuring the Frame Rate

Configuring the Delegate

Controlling Frame Updates

Obtaining Information About View Updates

Properties

delegate

The view controller’s delegate.

@property(nonatomic, assign) id<GLKViewControllerDelegate> delegate
Discussion

The delegate is optional.

Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h

framesDisplayed

The number of frame updates that have been sent by the view controller since it was created. (read-only)

@property(nonatomic, readonly) NSInteger framesDisplayed
Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h

framesPerSecond

The actual rate that the view controller attempts to call the view to update its contents. (read-only)

@property(nonatomic, readonly) NSInteger framesPerSecond
Discussion

The view controller attempts to maintain this frame rate, but it may still drop frames if the per-frame processing performed by your application takes more time than the time between frames.

Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h

paused

A Boolean value that indicates whether the rendering loop is paused.

@property(nonatomic, getter=isPaused) BOOL paused
Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h

pauseOnWillResignActive

A Boolean value that indicates whether the view controller automatically pauses the rendering loop when the application resigns the active state.

@property(nonatomic) BOOL pauseOnWillResignActive
Discussion

The default value is YES. If your application sets this to NO, it must explicitly set the paused property to YES when the application resigns the active state.

Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h

preferredFramesPerSecond

The rate you want the view controller to call the view to update the contents of the view.

@property(nonatomic) NSInteger preferredFramesPerSecond
Discussion

When your application sets its preferred frame rate, the view controller chooses a frame rate as close to that as possible based on the capabilities of the screen the view is displayed on. The actual frame rate chosen is usually a factor of the maximum refresh rate of the screen to provide a consistent frame rate. For example, if the maximum refresh rate of the screen is 60 frames per second, that is also the highest frame rate the view controller sets as the actual frame rate. However, if you ask for a lower frame rate, it might choose 30, 20, 15 or some other factor to be the actual frame rate.

Your application should choose a frame rate that it can consistently maintain.

The default value is 30 frames per second.

Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h

resumeOnDidBecomeActive

A Boolean value that indicates whether the view controller automatically resumes the rendering loop when the application becomes active.

@property(nonatomic) BOOL resumeOnDidBecomeActive
Discussion

The default value is YES. If your application sets this to NO, it must explicitly set the paused property to NO when the application becomes active.

Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h

timeSinceFirstResume

The amount of time that has passed since first time the view controller resumed sending update events. (read-only)

@property(nonatomic, readonly) NSTimeInterval timeSinceFirstResume
Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h

timeSinceLastDraw

The amount of time that has passed since the last time the view controller called the view’s display method. (read-only)

@property(nonatomic, readonly) NSTimeInterval timeSinceLastDraw
Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h

timeSinceLastResume

The amount of time that has passed since the last time the view controller resumed sending update events. (read-only)

@property(nonatomic, readonly) NSTimeInterval timeSinceLastResume
Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h

timeSinceLastUpdate

The amount of time that has passed since the last time the view controller called the delegate’s glkViewControllerUpdate: method. (read-only)

@property(nonatomic, readonly) NSTimeInterval timeSinceLastUpdate
Availability
  • Available in iOS 5.0 and later.
Declared In
GLKViewController.h