Swift 为什么动画和水平运动效果之间会发生这种奇怪的行为？

我测试了一些代码，最后得到了以下代码：

import UIKit

class ViewController: UIViewController {

 @IBOutlet var backgroundImageView: UIImageView!

 override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(true)
    hideAndShow()
 }

 func hideAndShow(){
    self.backgroundImageView.alpha = 0
    UIView.animateWithDuration(1.0, delay: 0, options: .Repeat | .AllowUserInteraction | .Autoreverse | UIViewAnimationOptions.CurveEaseOut, animations: { [weak self] in
        self?.backgroundImageView.alpha = 1
        }, completion: nil)
 }

 override func viewDidLoad() {
    super.viewDidLoad()

    self.backgroundImageView.contentMode = UIViewContentMode.Center;
    self.backgroundImageView.backgroundColor = UIColor(patternImage: UIImage(named: "640x1136launch")!)
    self.addParallaxEffectToView(self.backgroundImageView)
    self.backgroundImageView.frame = CGRectInset(self.backgroundImageView.frame, -50, -50);
 }

 func addParallaxEffectToView(view: UIView ) {
    // Set vertical effect
    var verticalMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.y", type: UIInterpolatingMotionEffectType.TiltAlongVerticalAxis)
    verticalMotionEffect.minimumRelativeValue = -50
    verticalMotionEffect.maximumRelativeValue = 50

    // Set horizontal effect
    var horizontalMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.x", type: UIInterpolatingMotionEffectType.TiltAlongHorizontalAxis)
    horizontalMotionEffect.minimumRelativeValue = -50
    horizontalMotionEffect.maximumRelativeValue = -50

    // Create group to combine both
    var group = UIMotionEffectGroup.new()
    group.motionEffects = [horizontalMotionEffect, verticalMotionEffect]

    // Add both effects to your view
    view.addMotionEffect(group);
 }
}

这段代码的作用是在我的

UIViewController

上的

UIImage

上产生闪烁效果

此图像还具有UIMotionEffect（在本例中为tilt）效果，在垂直倾斜设备时效果非常理想，但由于某些原因，在水平倾斜设备时效果不理想

尽管如此，关键是当我调用我的

hideandShow（）

函数时，我的视图开始闪烁，但同时，…开始水平移动

为什么会这样？我没有主意了