iOS 5 Programming Cookbook

16.2. Detecting the Availability of a Gyroscope

Problem

You want to find out whether the current iOS device that is running your program has gyroscope hardware available.

Solution

Use the isGyroAvailable method of an instance of CMMotionManager to detect the gyroscope hardware. The isGyroActive method is also available if you want to detect whether the gyroscope hardware is currently sending updates to your program (in other words, whether it is active):

- (BOOL)            application:(UIApplication *)application
  didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{

  CMMotionManager *motionManager = [[CMMotionManager alloc] init];

  if ([motionManager isGyroAvailable]){
    NSLog(@"Gryro is available.");
  } else {
    NSLog(@"Gyro is not available.");
  }

  if ([motionManager isGyroActive]){
    NSLog(@"Gryo is active.");
  } else {
    NSLog(@"Gryo is not active.");
  }

  self.window = [[UIWindow alloc] initWithFrame:
                 [[UIScreen mainScreen] bounds]];

  self.window.backgroundColor = [UIColor whiteColor];
  [self.window makeKeyAndVisible];
  return YES;
}

iOS Simulator does not have gyroscope simulation in place. If you run this code on the simulator, you will receive results similar to these in the console window:

Gyro is not available.
Gyro is not active.

If you run the same code on the original iPad, you will get the same results as you get from iOS Simulator. However, if you run this code on an iOS device with a gyroscope, such as the iPhone 4 or iPad 2, the results could be different:

Gyro is available. Gyro is not active. ...