Capture snapshot of unselected UITabBarItem? - swift

Question

I am writing some tutorial code for app, and would like to make screen shot of unselected tab bar item. Here is the code I have written so far:
extension UIView {
var globalFrame: CGRect {
superview?.convert(frame, to: nil) ?? .zero
}
}
extension UIView {
var snapshot: UIImage {
UIGraphicsImageRenderer(size: bounds.size).image { _ in
drawHierarchy(in: frame, afterScreenUpdates: false)
}
}
}
extension UITabBar {
func snapshotDataForTab(atIndex index: Int) -> (UIImage, CGRect) {
var tabs = subviews.compactMap { (view: UIView) -> UIControl? in
if let view = view as? UIControl {
return view
}
return nil
}
tabs.sort(by: { $0.frame.origin.x < $1.frame.origin.x })
return (tabs[index].snapshot, tabs[index].globalFrame)
}
}
Main controller:
class MainTabBarController: UITabBarController {
override func viewDidLoad() {
super.viewDidLoad()
selectedIndex = 0
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
self.presentTooltip(forTabAtIndex: 0)
}
}
private func presentTooltip(forTabAtIndex index: Int) {
let dimView = UIView(frame: view.frame)
dimView.backgroundColor = .red
view.addSubview(dimView)
let (image, frame) = tabBar.snapshotDataForTab(atIndex: index)
let imageView = UIImageView(image: image)
imageView.frame = frame
dimView.addSubview(imageView)
}
}
Interestingly enough everything works as expected when selectedIndex is 0 and I call presentTooltip for value 0. However if I call presentTooltip with 1, nothing is rendered. If I switch selectedIndex to 1, then it's reversed, and nothing gets rendered for presentTooltip with 0.
It seems I am unable to capture snapshot of inactive tab?

Answer 1

The snapshot function is buggy. I'm able to take snapshot of the unselected UITabbar item.
Below is the correct snapshot function:
var snapshot: UIImage {
let renderer = UIGraphicsImageRenderer(bounds: self.bounds)
return renderer.image { (context) in
self.layer.render(in: context.cgContext)
}
}
Check the project here Github Repo
This is the screenshot showing a snapshot of unselected UITabbaritem.