Hello, I'm new to SwiftUI and right now I'm trying to create one simple Application by using @State, @ObservedObject, and @Environment. For some reason, I got error "Cannot preview in this file" after I tried to add Environment object. The canvas is not working, but I can actually run the application in a simulator and actual device without any problem. Here is how I added my environment object. SceneDelegate:func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
// Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
// If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
// This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
let channelData = ChannelData()
// Create the SwiftUI view that provides the window contents.
let contentView = ContentView().environmentObject(channelData)
// Use a UIHostingController as window root view controller.
if let windowScene = scene as? UIWindowScene {
let window = UIWindow(windowScene: windowScene)
window.rootViewController = UIHostingController(rootView: contentView)
self.window = window
window.makeKeyAndVisible(
}
}ChannelData class:import Combine
final class ChannelData: ObservableObject{
@Published var channelName = "YouTube Channel"
}ContentView:import SwiftUI
struct ContentView: View {
@State private var showingSecondVC = false
@ObservedObject var videoIdea = VideoIdea()
@EnvironmentObject var channelData: ChannelData
var body: some View {
NavigationView{
VStack(alignment: .leading){
Text(videoIdea.title)
.font(.title)
Text(videoIdea.contentIdea)
.font(.subheadline)
Divider()
NavigationLink(destination: ChannelView()){
Text("Add Channel")
}
Button(action: {
self.showingSecondVC.toggle()
}){
Text("Add New Idea")
}.sheet(isPresented: $showingSecondVC){
SecondView(videoTitle: self.$videoIdea.title, videoContent: self.$videoIdea.contentIdea).environmentObject(self.channelData)
}
Spacer()
}.padding()
.navigationBarTitle(channelData.channelName)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}SecondView:import SwiftUI
struct SecondView: View {
@Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
@Binding var videoTitle: String
@Binding var videoContent: String
@EnvironmentObject var channelData:ChannelData
var body: some View {
NavigationView {
VStack(alignment: .leading){
TextField("Video title", text: $videoTitle)
TextField("Video Content", text: $videoContent)
Divider()
Button(action: {
self.presentationMode.wrappedValue.dismiss()
}){
Text("Dismiss this VC")
}
Spacer()
}.padding()
.navigationBarTitle(channelData.channelName)
}
}
}ChannelView:import SwiftUI
struct ChannelView: View {
@Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
@State private var channelName = "My Channel"
@EnvironmentObject var channelData: ChannelData
var body: some View {
NavigationView{
VStack(alignment: .leading){
TextField("Channel Name", text: $channelName)
Divider()
Button(action: {
self.presentationMode.wrappedValue.dismiss()
}){
Text("Dismiss this VS")
}
Spacer()
}.padding()
.navigationBarTitle(channelData.channelName)
}
}
}
www0488
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I'm trying to display one embedded content by using the WKWebView and I can not click some of these links. Is there anything I did wrong?Here is the Link which I get the embedded content from:https://publish.twitter.com Here is the embedded content:<a class="twitter-timeline" href="https://twitter.com/Google?ref_src=twsrc%5Etfw">Tweets by Google</a><script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>Here is my code:import UIKit
import WebKit
class ViewController: UIViewController {
private var mWebView: WKWebView!
let embeddedTwittContent = "<a class='twitter-timeline' href='https://twitter.com/Google?ref_src=twsrc%5Etfw'>Tweets by Google</a>" // let embeddedTwittContent = "<a class=\"twitter-timeline\" href=\"https://twitter.com/Smaforetagarna?ref_src=twsrc%5Etfw\">Tweets by Smaforetagarna</a>"
let scriptValue = "<script async src=\"https://platform.twitter.com/widgets.js\" charset=\"utf-8\"></script>"
let redirectLink = "https://twitter.com/Smaforetagarna/status/"
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
let preferences = WKPreferences()
preferences.javaScriptEnabled = true
let configuration = WKWebViewConfiguration()
configuration.websiteDataStore = WKWebsiteDataStore.nonPersistent()
configuration.preferences = preferences
self.mWebView = WKWebView(frame: CGRect.zero, configuration: configuration)
self.mWebView.translatesAutoresizingMaskIntoConstraints = false
self.mWebView.allowsLinkPreview = true
self.mWebView.allowsBackForwardNavigationGestures = true
self.mWebView.navigationDelegate = self
self.view.addSubview(self.mWebView)
// Add Constraints
self.mWebView.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 100).isActive = true
self.mWebView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: 0).isActive = true
self.mWebView.rightAnchor.constraint(equalTo: self.view.rightAnchor, constant: 0).isActive = true
self.mWebView.leftAnchor.constraint(equalTo: self.view.leftAnchor, constant: 0).isActive = true
loadTweetNews()
}
func loadTweetNews(){
let htmlHeader = "<!DOCTYPE html> <html><meta name=\'viewport\' content=\'initial-scale=1.0\'/> <head> \(scriptValue) </head> <body>"
let htmlFooter = "</body> </html>"
let orderHtml = htmlHeader + embeddedTwittContent + htmlFooter
let url: URL = URL(string: "https:")!
self.mWebView.loadHTMLString(orderHtml, baseURL: url)
}
}
extension ViewController: WKNavigationDelegate{
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
print("page finished load")
}
func webView(_ webView: WKWebView, didReceiveServerRedirectForProvisionalNavigation navigation: WKNavigation!) {
print("didReceiveServerRedirectForProvisionalNavigation: \(navigation.debugDescription)")
}
func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
print("didStartProvisionalNavigation")
}
func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
if navigationAction.navigationType == .linkActivated {
if let url = navigationAction.request.url,
UIApplication.shared.canOpenURL(url) {
UIApplication.shared.open(url)
print(url)
decisionHandler(.cancel)
} else {
decisionHandler(.allow)
}
} else {
decisionHandler(.allow)
}
}