ios – 如何截取UIView的部分截图？

因此,在Swift 2中：

extension UIView {

    /// Create snapshot
    ///
    /// - parameter rect: The `CGRect` of the portion of the view to return. If `nil` (or omitted),///                   return snapshot of the whole view.
    ///
    /// - returns: Returns `UIImage` of the specified portion of the view.

    func snapshot(of rect: CGRect? = nil) -> UIImage? {
        // snapshot entire view

        UIGraphicsBeginImageContextWithOptions(bounds.size,opaque,0)
        drawViewHierarchyInRect(bounds,afterScreenUpdates: true)
        let wholeImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        // if no `rect` provided,return image of whole view

        guard let rect = rect,let image = wholeImage else { return wholeImage }

        // otherwise,grab specified `rect` of image

        let scale = image.scale
        let scaledRect = CGRect(x: rect.origin.x * scale,y: rect.origin.y * scale,width: rect.size.width * scale,height: rect.size.height * scale)
        guard let cgImage = CGImageCreateWithImageInRect(image.CGImage!,scaledRect) else { return nil }
        return UIImage(CGImage: cgImage,scale: scale,orientation: .Up)
    }

}

在Swift 3中：

extension UIView {

    /// Create snapshot
    ///
    /// - parameter rect: The `CGRect` of the portion of the view to return. If `nil` (or omitted),isOpaque,0)
        drawHierarchy(in: bounds,return image of whole view

        guard let image = wholeImage,let rect = rect else { return wholeImage }

        // otherwise,height: rect.size.height * scale)
        guard let cgImage = image.cgImage?.cropping(to: scaledRect) else { return nil }
        return UIImage(cgImage: cgImage,orientation: .up)
    }

}

要使用它,您可以：

if let image = webView.snapshot(of: rect) {
    // do something with `image` here
}