iOS 7 Programming Cookbook

21.1. Detecting the Availability of an Accelerometer

Problem

In your program, you want to detect whether the accelerometer hardware is available.

Solution

Use the isAccelerometerAvailable method of CMMotionManager to detect the accelerometer hardware. The isAccelerometerActive method can also be used to detect whether the accelerometer hardware is currently sending updates to the program.

Let’s first make sure we have imported the required header files:

#import "AppDelegate.h"
#import <CoreMotion/CoreMotion.h>

@implementation AppDelegate

Next, go on to detect the availability of an accelerometer in the implementation file of our app delegate:

- (BOOL)            application:(UIApplication *)application
  didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{
    
    CMMotionManager *motionManager = [[CMMotionManager alloc] init];
    
    if ([motionManager isAccelerometerAvailable]){
        NSLog(@"Accelerometer is available.");
    } else{
        NSLog(@"Accelerometer is not available.");
    }
    
    if ([motionManager isAccelerometerActive]){
        NSLog(@"Accelerometer is active.");
    } else {
        NSLog(@"Accelerometer is not active.");
    }
    
    self.window = [[UIWindow alloc] initWithFrame:
                   [[UIScreen mainScreen] bounds]];
    
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}

Accelerometer hardware might be available on the iOS device running your program. This, however, does not mean the accelerometer hardware is sending updates to your program. If the accelerometer or gyroscope is sending updates to your ...