iOS CoreMotion 纪录步数

- (void)startUpdateAccelerometer
{
    /* 设置采样的频率，单位是秒 */
    NSTimeInterval updateInterval = 0.05; // 每秒采样20次
    
    //    CGSize size = [self superview].frame.size;
    //    __block CGRect f = [self frame];
    __block int stepCount = 0; // 步数
    //在block中，只能使用weakSelf。
    /* 判断是否加速度传感器可用，如果可用则继续 */
    if ([motionManager isAccelerometerAvailable] == YES) {
        /* 给采样频率赋值，单位是秒 */
        [motionManager setAccelerometerUpdateInterval:updateInterval];
        
        /* 加速度传感器开始采样，每次采样结果在block中处理 */
        [motionManager startAccelerometerUpdatesToQueue:[NSOperationQueue currentQueue] withHandler:^(CMAccelerometerData *accelerometerData, NSError *error)
         {
             
             CGFloat sqrtValue =sqrt(accelerometerData.acceleration.x*accelerometerData.acceleration.x+accelerometerData.acceleration.y*accelerometerData.acceleration.y+accelerometerData.acceleration.z*accelerometerData.acceleration.z);
             
             // 走路产生的震动率
             if (sqrtValue > 1.552188 && valiadCountStep)
             {
                 displayLink.paused = NO;
                 [Database save:TableLocalFoot entity:[NSDictionary dictionaryWithObjectsAndKeys:@"1",@"footid",[[NSUserDefaults standardUserDefaults] valueForKey:@"token"],@"userid",[NSDate date],@"time", nil]];
                 
//                 [self.delegate totleNum:stepCount];
                 stepCount +=1;
                 valiadCountStep = NO;
             }
             
         }];
    }
    
}