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 UIKitextension 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}