How do I screenshot a uiview without adding it to the subview? - ios

Question

I have multiple subviews on a parent view, and I need to convert the uiview to a uiimage but of only certain subviews. So I added a tag to the views I needed to take a screenshot of and added it to its own view, but when I try to screenshot that I get a black screen. However, when I use the regular parent view I get a photo with all the subviews.
let viewPic = UIView()
for subview in self.view.subviews {
if(subview.tag == 6) {
viewPic.addSubview(subview)
}
if(subview.tag == 8) {
viewPic.addSubview(subview)
}
}
let picImage = viewPic.getSnapshotImage() //This is a black screen
getSnapshotImage
extension UIView {
public func getSnapshotImage() -> UIImage {
UIGraphicsBeginImageContextWithOptions(self.bounds.size, self.isOpaque, 0)
self.drawHierarchy(in: self.bounds, afterScreenUpdates: false)
let snapshotItem: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return snapshotItem
}
}

Answer 1

First of all, your viewPic doesn't set the frame size so the default will be zero frame which may cause the issue.
Secondly, I tried to use your getSanpshotImage() on my sample project, but I always get the blank image.
Have a look at the demo code, I can get what you want (see the screenshot):
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let viewPic = UIView()
viewPic.frame = self.view.frame
let view1 = UIView()
view1.frame = CGRect(x: 0, y: 0, width: 100, height: 100)
view1.backgroundColor = UIColor.red
viewPic.addSubview(view1)
let view2 = UIView()
view2.frame = CGRect(x: 0, y: 200, width: 100, height: 100)
view2.backgroundColor = UIColor.blue
viewPic.addSubview(view2)
let picImage = viewPic.convertToImage() //This is a black screen
print(picImage)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
extension UIView {
func convertToImage() -> UIImage {
let renderer = UIGraphicsImageRenderer(bounds: bounds)
return renderer.image { rendererContext in
layer.render(in: rendererContext.cgContext)
}
}
}