实现重按一张图片，快速阅览图片。
1、注册View接受3D touch动作。
registerForPreviewing(with:self, sourceView: cell)
2. 写一个ViewController 里面有个 UIImageView 预览图片。
3. 实现 UIViewControllerPreviewingDelegate 协议。
extension ChoosePhotoCC : UIViewControllerPreviewingDelegate {
func previewingContext(_ previewingContext: UIViewControllerPreviewing, commit viewControllerToCommit: UIViewController) {
}
func previewingContext(_ previewingContext: UIViewControllerPreviewing, viewControllerForLocation location: CGPoint) -> UIViewController? {
if let vc = self.storyboard?.instantiateViewController(withIdentifier: "ImagePreviewVC") as? ImagePreviewVC{
vc.loadImage(asset: assets[previewingContext.sourceView.tag])
return vc
}
return nil
}
}