iOS 截图

public extension UIView {
    // 截取全图
    func snapshotImage(afterUpdates: Bool) -> UIImage? {
        UIGraphicsBeginImageContextWithOptions(bounds.size, isOpaque, 0)
        drawHierarchy(in: bounds, afterScreenUpdates: afterUpdates)
        let snap = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return snap
    }
    
    // 截取指定区域图
    func snapshotImage(in rect: CGRect, afterUpdates: Bool, scale: CGFloat = UIScreen.main.scale) -> UIImage? {
        let realRect = CGRect(x: rect.minX*scale, y: rect.minY*scale, width: rect.width*scale, height: rect.height*scale)
        
        let image = snapshotImage(afterUpdates: afterUpdates)
        guard let cgImage = image?.cgImage?.cropping(to: realRect) else { return nil }
        return UIImage(cgImage: cgImage)
    }
}