Draw All PDF Annotations as Overlays in Swift for iOS

1
//
2
//  Copyright © 2021-2025 PSPDFKit GmbH. All rights reserved.
3
//
4
//  The Nutrient sample applications are licensed with a modified BSD license.
5
//  Please see License for details. This notice may not be removed from this file.
6
//
7

8
import PSPDFKit
9
import PSPDFKitUI
10

11
/// This is an example showing how to modify all annotations to render as overlays.
12
/// Note that this is a corner case and isn't as well tested.
13
/// This helps in case you want to add custom subviews but still have drawings on top of everything.
14
class DrawAnnotationsAsOverlayExample: Example, PDFViewControllerDelegate {
15

16
    override init() {
17
        super.init()
18

19
        title = "Draw all annotations as overlay"
20
        contentDescription = "Allows annotations to render on top of custom subviews of the page view."
21
        category = .subclassing
22
        priority = 150
23
    }
24

25
    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController? {
26
        let document = AssetLoader.document(for: .annualReport)
27

28
        // Register our custom annotation provider as subclass before the view controller is initialized.
29
        document.overrideClass(PDFFileAnnotationProvider.self, with: OverlayFileAnnotationProvider.self)
30

31
        let pdfViewController = PDFViewController(document: document)
32
        pdfViewController.navigationItem.setRightBarButtonItems([pdfViewController.thumbnailsButtonItem, pdfViewController.annotationButtonItem], for: .document, animated: false)
33
        pdfViewController.delegate = self
34

35
        return pdfViewController
36
    }
37

38
    // MARK: PDFViewControllerDelegate
39

40
    func pdfViewController(_ pdfController: PDFViewController, didConfigurePageView pageView: PDFPageView, forPageAt pageIndex: Int) {
41
        // Add a custom view on every page to demonstrate that the annotations will render ABOVE that view.
42
        let customView = CustomView(frame: CGRect(x: 100, y: 100, width: 300, height: 300))
43
        customView.backgroundColor = UIColor(red: 1, green: 0.846, blue: 0.088, alpha: 0.9)
44
        customView.layer.cornerRadius = 10
45
        customView.layer.borderColor = UIColor(red: 1, green: 0.846, blue: 0.088, alpha: 1).cgColor
46
        customView.layer.borderWidth = 2
47
        customView.alpha = 0.5
48

49
        pageView.insertSubview(customView, belowSubview: pageView.annotationContainerView)
50
    }
51

52
    func pdfViewController(_ pdfController: PDFViewController, didCleanupPageView pageView: PDFPageView, forPageAt pageIndex: Int) {
53
        pageView.subviews.first { $0 is CustomView }?.removeFromSuperview()
54
    }
55
}
56

57
private class CustomView: UIView {
58
}
59

60
private class OverlayFileAnnotationProvider: PDFFileAnnotationProvider {
61

62
    override func annotationsForPage(at pageIndex: PageIndex) -> [Annotation]? {
63
        let annotations = super.annotationsForPage(at: pageIndex) ?? []
64

65
        // Make annotations overlay annotations so they will be rendered in their own views instead of within the page image.
66
        // Making highlights as overlay really really doesn't look good. (Since they are multiplied into the page content this is not possible with regular UIView composition, so you would need to completely overlap the text unless you make them semi-transparent.)
67
        for annotation in annotations where annotation is TextMarkupAnnotation == false {
68
            annotation.isOverlay = true
69
        }
70

71
        return annotations
72
    }
73

74
    override func add(_ annotations: [Annotation], options: [AnnotationManager.ChangeBehaviorKey: Any]? = nil) -> [Annotation]? {
75
        // Set annotations to render as overlays right after they are inserted.
76
        for annotation in annotations where annotation is TextMarkupAnnotation == false {
77
            annotation.isOverlay = true
78
        }
79

80
        return super.add(annotations, options: options)
81
    }
82
}