iOS裁切一个圆形图片-swift

// 图片裁切
let orgImag = UIImage(named: "2.jpg")
// 1 开启位图上下文  跟图片的尺寸一样大
UIGraphicsBeginImageContextWithOptions((orgImag?.size)!, false, 0)

// 2 设置原型裁剪区域， 正切与图片
let path = UIBezierPath(ovalInRect: CGRectMake(0, 0, (orgImag?.size.height)!, (orgImag?.size.height)!))

// 2.1 把路径设置为裁切区域
path.addClip()

// 3 绘制图片
orgImag?.drawAtPoint(CGPointZero)

// 4 从上下文中获取图片
let ovrWater = UIGraphicsGetImageFromCurrentImageContext()

// 5 关闭上下文
UIGraphicsEndImageContext()

let imageView = UIImageView(frame: CGRectMake(0, 0, 250, 250))
imageView.image = ovrWater
imageView.backgroundColor = UIColor.clearColor()
imageView.contentMode = UIViewContentMode.ScaleAspectFit

view.addSubview(imageView)