用MotionManager iOS替换sharedAccelerometer

Question

I've tried several method but I cannot find a working method to replace my

[[UIAccelerometer sharedAccelerometer] setUpdateInterval:(1.0 / kAccelerometerFrequency)];
[[UIAccelerometer sharedAccelerometer] setDelegate:self];

most recently i've tried to replace that with

motionManager = [[CMMotionManager alloc] init];
motionManager.accelerometerUpdateInterval = (1.0 / kAccelerometerFrequency);

But it does not seem to work with my void

- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {
    CGPoint pt = theCar.center;
    CGFloat accel = acceleration.x * kAccelerationSpeed;

float halfCarWidth = theCar.frame.size.width / 2;
    if(pt.x - halfCarWidth + accel > 0 && pt.x + halfCarWidth + accel < 320) {
        pt.x += accel;
    }

    [theCar setCenter:pt];
}

So what do I replace the sharedAccelerometer with since it was depreciated in iOS 5

Answer 1

There is no delegate message with motion manager. Use a timer (NSTimer) and poll the motion manager for its values, at intervals.

self.motman = [CMMotionManager new];
if (!self.motman.accelerometerAvailable) {
    // report error or whatever
    return;
}
self.motman.accelerometerUpdateInterval = 1.0 / 30.0;
[self.motman startAccelerometerUpdates];
self.timer =
    [NSTimer
        scheduledTimerWithTimeInterval:self.motman.accelerometerUpdateInterval
        target:self selector:@selector(pollAccel:) userInfo:nil repeats:YES];

Now pollAccel: is called repeatedly. Pull out the accelerometer info:

CMAccelerometerData* dat = self.motman.accelerometerData;
CMAcceleration acc = dat.acceleration;