iOS Swift3.0异步设置任意弧度高性能圆角图片

写一个UIImage的分类,方便调用

import UIKit

extension UIImage {

/// 异步设置圆角图片
///
/// - Parameters:
///   - size:       图片大小
///   - radius:     圆角值
///   - fillColor:  裁切区域填充颜色
///   - completion: 回调裁切结果图片
func cornerImage(size:CGSize, radius:CGFloat, fillColor: UIColor, completion:@escaping ((_ image: UIImage)->())) -> Void {

//异步绘制裁切
DispatchQueue.global().async {
//利用绘图建立上下文
UIGraphicsBeginImageContextWithOptions(size, true, 0)

let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)

//设置填充颜色
fillColor.setFill()
UIRectFill(rect)

//利用贝塞尔路径裁切
let path = UIBezierPath.init(roundedRect: rect, cornerRadius: radius)
path.addClip()

self.draw(in: rect)

//获取结果
let resultImage = UIGraphicsGetImageFromCurrentImageContext()

//关闭上下文
UIGraphicsEndImageContext()

//主队列回调
DispatchQueue.main.async {
completion(resultImage!)
}
}
}
}

调用绘制方法

let image = UIImage(named: "imageName")
image?.cornerImage(size: CGSize(width: 200, height: 200), radius:30, fillColor: UIColor.white) { (resultImage: UIImage) in
self.imageView.image = resultImage
}