使用BCMeshTransformView時沒有任何顯示

我想將BCMeshTransformView庫用於我的swift項目。我創建了一個空的swift項目，並通過可可豆莢添加了該庫。使用BCMeshTransformView時沒有任何顯示

這裏是我的ViewController類：

import UIKit 
import BCMeshTransformView 

class ViewController: UIViewController { 

    var transformView:BCMeshTransformView! 
    var imageView:UIImageView! 
    var transform:BCMutableMeshTransform! 

    override func viewDidLoad() { 
     super.viewDidLoad() 
     // Do any additional setup after loading the view, typically from a nib. 

     transformView = BCMeshTransformView(frame: self.view.bounds) 
     transformView.autoresizingMask = [.flexibleWidth, .flexibleHeight] 

     imageView = UIImageView(image: UIImage(named: "picture.jpg")!) 
     imageView.center = CGPoint(x: transformView.contentView.bounds.midX, y: transformView.contentView.bounds.midY) 

     transformView.contentView.addSubview(imageView) 

     transformView.diffuseLightFactor = 0.0 

     transform = BCMutableMeshTransform.identityMeshTransform(withNumberOfRows: 20, numberOfColumns: 20) 

     transform.mapVertices { (vertex, vertexIndex) -> BCMeshVertex in 
      return BCMeshVertex(from: vertex.from, to: vertex.to) 
     } 

     transformView.meshTransform = transform 

     self.view.addSubview(transformView) 
    } 

}

當我運行的應用程序沒有被顯示。它完全是白色的。

刪除此代碼：

transform = BCMutableMeshTransform.identityMeshTransform(withNumberOfRows: 20, numberOfColumns: 20) 

transform.mapVertices { (vertex, vertexIndex) -> BCMeshVertex in 
    return BCMeshVertex(from: vertex.from, to: vertex.to) 
} 

transformView.meshTransform = transform

不會改變任何東西。

但是，當在Xcode我切換到「查看UI層次」我可以看到一個圖像：