有没有办法得到震动的强度？

Question

我正在做POC，看看是否能找到震动的强度。

class ViewController: UIViewController {
    override func motionBegan(motion: UIEventSubtype, withEvent event: UIEvent) {
        println("started shaking!")
    }

    override func motionEnded(motion: UIEventSubtype, withEvent event: UIEvent) {
        println("ended shaking!")
    }
}

我看不出有什么东西能告诉我摇晃有多强烈。在我的例子中，这种震动可能是持续几秒钟的事件。

Answer 1

这是我在didAccelerate回调中使用的一些类变量和常量的代码：

UIAccelerationValue accelX, accelY, accelZ;
#define  kAccelerometerFrequency 25 //Hz
#define  kFilteringFactor 0.1
#define  kMinShakeInterval 0.1
#define  kShakeAccelerationThreshold 0.2
-(CMMotionManager*) motionManager{
    if (_motionManager==nil) {
        _motionManager=[[CMMotionManager alloc] init];
        _motionManager.accelerometerUpdateInterval=1.0/25;
        _motionManager.gyroUpdateInterval=1.0/25;
    }
    return _motionManager;
}
-(void) viewDidLoad{
   [...]
   [[self motionManager] startAccelerometerUpdatesToQueue:[NSOperationQueue currentQueue]
                                           withHandler:^(CMAccelerometerData  *accelerometerData, NSError *error) {
                                               [self didAccelerate:accelerometerData.acceleration];
                                               if(error){
                                                   NSLog(@"%@", error);
                                               }
                                           }];
    [...]
}

- (void)didAccelerate:(CMAcceleration)acceleration{
    UIAccelerationValue lenght, x, y, z;
    accelX=acceleration.x*kFilteringFactor + accelX * (1.0 - kFilteringFactor);
    accelY=acceleration.y*kFilteringFactor + accelY * (1.0 - kFilteringFactor);
    accelZ=acceleration.z*kFilteringFactor + accelZ * (1.0 - kFilteringFactor);

    x=acceleration.x - accelX;
    y=acceleration.y - accelY;
    z=acceleration.z - accelZ;

    lenght=sqrt(x*x + y*y + z*z);
    if (lenght>=kShakeAccelerationThreshold && (CFAbsoluteTimeGetCurrent()>lastTime + kMinShakeInterval)){
    //execute shaking actions on main thread
    }
}

Answer 2

您可以使用CoreMotion框架读取加速度计值的原始流。