Question

From what I can tell, my app should be firing accelerometer events while Im using the iPad simulator in XCode, but its not.

I have googled around and it somewhat seems that the accelerometer is not implemented in the simulator, is this correct? If so, why on earth would they have a “Hardware->Shake Gesture” menu option?

My code is as follows:

.h file:

@interface MyViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate, UIAccelerometerDelegate>{
    UIAccelerometer *accelerometer;
    //...other stuff
}
@property (nonatomic, retain) UIAccelerometer *accelerometer;
@end

then the .m file:

@implementation MyViewController
@synthesize accelerometer;
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {
    NSLog(@"%@", [NSString stringWithFormat:@"%@%f", @"X: ", acceleration.x]);
    NSLog(@"%@", [NSString stringWithFormat:@"%@%f", @"Y: ", acceleration.y]);
    NSLog(@"%@", [NSString stringWithFormat:@"%@%f", @"Z: ", acceleration.z]);
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.accelerometer = [UIAccelerometer sharedAccelerometer];
    self.accelerometer.updateInterval = .1;
    self.accelerometer.delegate = self;
}
@end

Does this look right?

Answer 1

There’s no accelerator in the simulator.

The “Hardware → Shake Gesture” is generated by directly sending a UIEvent to the active application.

Although Shake Gesture is implemented using the accelerator on the device, conceptually they are two different kind of user input — the gesture is an event, the acceleration is continuous variation. Thus the Shake Gesture menu item exists for the apps which only use such gesture (e.g. Shake to Undo) but do not need to know the exact acceleration vector.