Swift CATransformLayer

CATransformLayer不同于普通的CALayer，因为它不能显示她自己的内容，只有当存在了一个能作用域子图层的变换它才真正存在。CATransformLayer并不平面化它的子图层，所以它能够用于构造一个层级的3D结构。
下面我们代码演示CATransformLayer的基本使用，创建立方体放置在一个CATransformLayer中，然后将两个这样的立方体放进容器中。
<pre>import UIKit

class ViewController: UIViewController {

var containerView: UIView!

override func viewDidLoad() {
    super.viewDidLoad()
   
    self.containerView = UIView()
    self.containerView.frame = self.view.bounds
    self.containerView.backgroundColor = UIColor.groupTableViewBackground
    self.view.addSubview(self.containerView)
    
    var pt = CATransform3DIdentity
    pt.m34 = -1.0 / 500.0
    self.containerView.layer.sublayerTransform = pt
    
    var c1t = CATransform3DIdentity
    c1t = CATransform3DTranslate(c1t, -100, 0, 0)
    let cube1 = self.cubeWithTransform(transform: c1t)
    self.containerView.layer.addSublayer(cube1)
    
    var c2t = CATransform3DIdentity
    c2t = CATransform3DTranslate(c2t, 100, 0, 0)
    c2t = CATransform3DRotate(c2t, -(CGFloat)(M_PI_4), 1, 0, 0)
    c2t = CATransform3DRotate(c2t, -(CGFloat)(M_PI_4), 0, 1, 0)
    let cube2 = self.cubeWithTransform(transform: c2t)
    self.containerView.layer.addSublayer(cube2)
}

func faceWithTransform(transform: CATransform3D) -> CALayer
{
    let face = CALayer()
    face.frame = CGRect(x: -50, y: -50, width: 100, height: 100)
    
    let red = arc4random() % 256
    let green = arc4random() % 256
    let blue = arc4random() % 256
    
    face.backgroundColor = UIColor(red: CGFloat(red) / 255, green: CGFloat(green) / 255, blue: CGFloat(blue) / 255, alpha: 1).cgColor
    face.transform = transform
    
    return face
}

func cubeWithTransform(transform: CATransform3D) -> CALayer
{
    let cube = CATransformLayer()
    // 1
    var ct = CATransform3DMakeTranslation(0, 0, 50)
    cube.addSublayer(self.faceWithTransform(transform: ct))
    // 2
    ct = CATransform3DMakeTranslation(50, 0, 0)
    ct = CATransform3DRotate(ct, CGFloat(M_PI_2), 0, 1, 0)
    cube.addSublayer(self.faceWithTransform(transform: ct))
    // 3
    ct = CATransform3DMakeTranslation(0, -50, 0)
    ct = CATransform3DRotate(ct, CGFloat(M_PI_2), 1, 0, 0)
    cube.addSublayer(self.faceWithTransform(transform: ct))
    // 4
    ct = CATransform3DMakeTranslation(0, 50, 0)
    ct = CATransform3DRotate(ct, CGFloat(-M_PI_2), 1, 0, 0)
    cube.addSublayer(self.faceWithTransform(transform: ct))
    // 5
    ct = CATransform3DMakeTranslation(-50, 0, 0)
    ct = CATransform3DRotate(ct, CGFloat(-M_PI_2), 0, 1, 0)
    cube.addSublayer(self.faceWithTransform(transform: ct))
    // 6
    ct = CATransform3DMakeTranslation(0, 0, -50)
    ct = CATransform3DRotate(ct, CGFloat(M_PI), 0, 1, 0)
    cube.addSublayer(self.faceWithTransform(transform: ct))
    
    let containerSize = self.containerView.bounds.size
    cube.position = CGPoint(x: containerSize.width / 2, y: containerSize.height / 2)
    cube.transform = transform
    
    return cube
}

}
</pre>

效果图

1.png