尝试创建一个彩色的圆形UIImage，但它总是以正方形结束。为什么？

import UIKit

func createCircularImage(color: UIColor, size: CGSize) -> UIImage? {
    UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
    guard let context = UIGraphicsGetCurrentContext() else {
        return nil
    }
    
    let rect = CGRect(origin: .zero, size: size)
    
    // 绘制圆形路径
    context.addEllipse(in: rect)
    context.clip()
    
    // 填充颜色
    context.setFillColor(color.cgColor)
    context.fill(rect)
    
    // 获取裁剪后的UIImage
    let circularImage = UIGraphicsGetImageFromCurrentImageContext()
    
    UIGraphicsEndImageContext()
    
    return circularImage
}

// 使用示例
let color = UIColor.red
let size = CGSize(width: 100, height: 100)
let circularImage = createCircularImage(color: color, size: size)