Introspect for SwiftUI

  

Introspect allows you to get the underlying UIKit or AppKit element of a SwiftUI view.

For instance, with Introspect you can access UITableView to modify separators, or UINavigationController to customize the tab bar.

How it works

Introspect works by adding a custom IntrospectionView to the view hierarchy, then looking into the UIKit hierarchy to find the relevant view.

For instance, when introspecting a TextField, it will:

• Add IntrospectionView as an overlay of TextField
• Get the view host of the introspection view (which is alongside the view host of the UITextField)
• Get the previous sibling containing UITextField

Please note that this introspection method might break in future SwiftUI releases. Future implementations might not use the same hierarchy, or might not use UIKit elements that are being looked for. Though the library is unlikely to crash, the .introspect() method will not be called in those cases.

Usage in production

Introspect is meant to be used in production. It does not use any private API. It only inspects the view hierarchy using publicly available methods. The library takes a defensive approach to inspecting the view hierarchy: there is no hard assumption that elements are laid out a certain way, there is no force-cast to UIKit classes, and the introspect() methods are simply ignored if UIKit views cannot be found.

Install

SwiftPM

https://github.com/siteline/SwiftUI-Introspect.git

Cocoapods

pod 'Introspect'

Introspection

Implemented

SwiftUI	UIKit	AppKit	Introspect
NavigationView (StackNavigationViewStyle)	UINavigationController	N/A	.introspectNavigationController()
NavigationView (DoubleColumnNavigationViewStyle)	UISplitViewController	N/A	.introspectSplitViewController()
Any embedded view	UIViewController	N/A	.introspectViewController()
ScrollView	UIScrollView	NSScrollView	.introspectScrollView()
List	UITableView	NSTableView	.introspectTableView()
View in List	UITableViewCell	NSTableCellView	introspectTableViewCell()
TabView	UITabBarController	NSTabView	.introspectTabBarController() (iOS) .introspectTabView() (macOS)
TextField	UITextField	NSTextField	.introspectTextField()
Toggle	UISwitch	NSButton	.introspectSwitch() (iOS) .introspectButton() (macOS)
Slider	UISlider	NSSlider	.introspectSlider()
Stepper	UIStepper	NSStepper	.introspectStepper()
DatePicker	UIDatePicker	NSDatePicker	.introspectDatePicker()
Picker (SegmentedPickerStyle)	UISegmentedControl	NSSegmentedControl	.introspectSegmentedControl()
Button	N/A	NSButton	.introspectButton()
ColorPicker	UIColorWell	NSColorWell	.introspectColorWell()
TextEditor	UITextView	NSTextView	.introspectTextView()

Missing an element? Please create an issue. As a temporary solution, you can implement your own selector.

Cannot implement

SwiftUI	Affected Frameworks	Why
Text	UIKit, AppKit	Not a UILabel / NSLabel
Image	UIKit, AppKit	Not a UIImageView / NSImageView
Button	UIKit	Not a UIButton

Examples

List

List {
    Text("Item 1")
    Text("Item 2")
}
.introspectTableView { tableView in
    tableView.separatorStyle = .none
}
.introspectTableViewCell { cell in
    let backgroundView = UIView()
    backgroundView.backgroundColor = .clear
    cell.selectedBackgroundView = backgroundView
}

ScrollView

ScrollView {
    Text("Item 2")
}
.introspectScrollView { scrollView in
    scrollView.refreshControl = UIRefreshControl()
}

NavigationView

NavigationView {
    Text("Item 2")
    .introspectNavigationController { navigationController in
        navigationController.navigationBar.backgroundColor = .red
    }
}

TextField

TextField("Text Field", text: $textFieldValue)
.introspectTextField { textField in
    textField.layer.backgroundColor = UIColor.red.cgColor
}

Implement your own selector

Missing an element? Please create an issue.

In case Introspect doesn't support the SwiftUI element that you're looking for, you can implement your own selector. For example, to look for a UITextField:

extension View {
    public func introspectTextField(customize: @escaping (UITextField) -> ()) -> some View {
        return inject(UIKitIntrospectionView(
            selector: { introspectionView in
                guard let viewHost = Introspect.findViewHost(from: introspectionView) else {
                    return nil
                }
                return Introspect.previousSibling(containing: UITextField.self, from: viewHost)
            },
            customize: customize
        ))
    }
}

You can use any of the following methods to inspect the hierarchy:

• Introspect.findChild(ofType:in:)
• Introspect.findChildUsingFrame(ofType:in:from:)
• Introspect.previousSibling(containing:from:)
• Introspect.nextSibling(containing:from:)
• Introspect.findAncestor(ofType:from:)
• Introspect.findHostingView(from:)
• Introspect.findViewHost(from:)

Releasing

• Increment version number:

$ bundle exec fastlane run increment_version_number bump_type:minor # major|minor|patch

• Update changelog with new version
• Bump version in Introspect.podspec
• Commit and push changes
• Tag new version:

$ git tag -a <VERSION> -m "<MESSAGE>"
$ git push origin --tags

• Push to cocoapods trunk:

$ bundle exec pod trunk push .