在其X轴(水平轴)上旋转UIView

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        let myView = UIView(frame: CGRect(x: 50, y: 50, width: 100, height: 100))
        myView.backgroundColor = .red
        self.view.addSubview(myView)

        // 在X轴上旋转45度
        let rotationAngle = CGFloat(45 * Double.pi / 180)
        let xTransform = CATransform3DMakeRotation(rotationAngle, 1, 0, 0)
        myView.layer.transform = xTransform
    }
}