Using a UIKit or AppKIt View in SwiftUI

When to Wrap a UIKit or AppKit View

There are two cases where you would wrap a UIKit or AppKit view in a SwiftUI app. The first case is your app needs a view that SwiftUI doesn’t have. If your app needs to show web content or a PDF file, you must use a WebKit web view or PDFKit’s PDF view. SwiftUI currently doesn’t have a native web view or PDF view.

The second case is your app needs to do something that a SwiftUI view can’t do. To let people edit rich text in your app, you must use UITextView or NSTextView. SwiftUI’s TextEditor view only allows plain text editing. Text views are a common control where you have to drop down to UIKit or AppKit because SwiftUI’s text editor is very limited currently.

Wrapping a UIKit or AppKit View

To wrap a UIKIt or AppKit view in a SwiftUI app, perform the following steps:

Create a struct that conforms to the UIViewRepresentable(iOS) or NSViewRepresentable(Mac) protocols.
Write a makeUIView or makeNSView function to create the UIKit or AppKit view.
Write a updateUIView or updateNSView view to handle view updates.

The following code creates a web view that displays HTML text:

import WebKit
import SwiftUI

struct WebView: UIViewRepresentable {
    var html: String
    
    init(html: String) {
        self.html = html
    }
    
    func makeUIView(context: Context) -> WKWebView {
        let webView = WKWebView()
        return webView
    }
    
    func updateUIView(_ uiView: WKWebView, context: Context) {
        uiView.loadHTMLString(html, baseURL: nil)
    }
}

import WebKit

import SwiftUI

struct WebView: UIViewRepresentable {

var html: String

init(html: String) {

self.html = html

}

func makeUIView(context: Context) -> WKWebView {

let webView = WKWebView()

return webView

}

func updateUIView(_ uiView: WKWebView, context: Context) {

uiView.loadHTMLString(html, baseURL: nil)

}

Notice that makeUIView returns the view type. The view type is also the type of the first argument to updateUIView.

After creating the view struct, you can add the view as part of the body of a SwiftUI view the same way you would add one of SwiftUI’s native views.

Examples and Further Reading

I have a demo project on GitHub that wraps a web view in a multi-platform SwiftUI app.

The CodeEditor package wraps a text view that supports syntax highlighting. It’s a more complex example than my demo project.

The following articles have additional information on using UIKit and AppKit views in SwiftUI: