iOS使用CoreMotion实现摇一摇功能

//ViewController 加入以下两方法 
-(BOOL)canBecomeFirstResponder 
{ 
//让当前controller可以成为firstResponder，这很重要 
  return YES; 
} 
-(void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event 
{ 
  if (event.subtype==UIEventSubtypeMotionShake) { 
    //做你想做的事 
  } 
} 
//在viewDidView中调用以下消息，主动让当前controller成为firstResponder 
[self becomeFirstResponder]; 
//已经不需要其它多余代码了 

#import <CoreMotion/CoreMotion.h> 

@property (strong,nonatomic) CMMotionManager *motionManager; 

self.motionManager = [[CMMotionManager alloc] init];//一般在viewDidLoad中进行 
self.motionManager.accelerometerUpdateInterval = .1;//加速仪更新频率，以秒为单位 

-(void)viewDidAppear:(BOOL)animated 
{ 
  [self startAccelerometer]; 
} 
-(void)startAccelerometer 
{ 
  //以push的方式更新并在block中接收加速度 
  [self.motionManager startAccelerometerUpdatesToQueue:[[NSOperationQueue alloc]init] 
     withHandler:^(CMAccelerometerData *accelerometerData, NSError *error) { 
    [self outputAccelertionData:accelerometerData.acceleration]; 
    if (error) { 
      NSLog(@"motion error:%@",error); 
    } 
  }]; 
} 
-(void)outputAccelertionData:(CMAcceleration)acceleration 
{ 
  //综合3个方向的加速度 
  double accelerameter =sqrt( pow( acceleration.x , 2 ) + pow( acceleration.y , 2 ) 
     + pow( acceleration.z , 2) ); 
  //当综合加速度大于2.3时，就激活效果（此数值根据需求可以调整，数据越小，用户摇动的动作就越小，越容易激活，反之加大难度，但不容易误触发） 
  if (accelerameter>2.3f) { 
 //立即停止更新加速仪（很重要！） 
    [self.motionManager stopAccelerometerUpdates]; 
     
    dispatch_async(dispatch_get_main_queue(), ^{ 
      //UI线程必须在此block内执行，例如摇一摇动画、UIAlertView之类 
    }); 
  }   
} 
-(void)viewDidDisappear:(BOOL)animated 
{ 
  //停止加速仪更新（很重要！） 
  [self.motionManager stopAccelerometerUpdates]; 
} 

//viewDidAppear中加入 
[[NSNotificationCenter defaultCenter] addObserver:self 
     selector:@selector(receiveNotification:) 
     name:UIApplicationDidEnterBackgroundNotification object:nil]; 
[[NSNotificationCenter defaultCenter] addObserver:self 
     selector:@selector(receiveNotification:) 
     name:UIApplicationWillEnterForegroundNotification object:nil]; 

//viewDidDisappear中取消监听 
[[NSNotificationCenter defaultCenter] removeObserver:self 
     name:UIApplicationDidEnterBackgroundNotification object:nil]; 
[[NSNotificationCenter defaultCenter] removeObserver:self 
     name:UIApplicationWillEnterForegroundNotification object:nil]; 

//对应上面的通知中心回调的消息接收 
-(void)receiveNotification:(NSNotification *)notification 
{ 
  if ([notification.name  
    isEqualToString:UIApplicationDidEnterBackgroundNotification]) 
  { 
    [self.motionManager stopAccelerometerUpdates]; 
  }else{ 
    [self startAccelerometer]; 
 }}