- (void)startUpdateAccelerometer
{
    /* 設(shè)置采樣的頻率，單位是秒 */
    NSTimeInterval updateInterval = 0.05; // 每秒采樣20次
    
    //    CGSize size = [self superview].frame.size;
    //    __block CGRect f = [self frame];
    __block int stepCount = 0; // 步數(shù)
    //在block中，只能使用weakSelf。
    /* 判斷是否加速度傳感器可用，如果可用則繼續(xù) */
    if ([motionManager isAccelerometerAvailable] == YES) {
        /* 給采樣頻率賦值，單位是秒 */
        [motionManager setAccelerometerUpdateInterval:updateInterval];
        
        /* 加速度傳感器開始采樣，每次采樣結(jié)果在block中處理 */
        [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);
            
             // 走路產(chǎn)生的震動率
             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;
             }
            
         }];
    }
    
}