Add preload banner to sample app

Samples/MobileBuyIntegration/MobileBuyIntegration.xcodeproj/project.pbxproj

@@ -22,6 +22,8 @@
 		4EF54F242A6F456B00F5E407 /* CartManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4EF54F232A6F456B00F5E407 /* CartManager.swift */; };
 		4EF54F272A6F4C4F00F5E407 /* CartViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4EF54F262A6F4C4F00F5E407 /* CartViewController.swift */; };
 		4EF54F312A6F63C000F5E407 /* CartViewController.xib in Resources */ = {isa = PBXBuildFile; fileRef = 4EF54F2F2A6F63C000F5E407 /* CartViewController.xib */; };
+		6A8D64D22AF2A10600FE4E4A /* ShopifyCheckout in Frameworks */ = {isa = PBXBuildFile; productRef = 6A8D64D12AF2A10600FE4E4A /* ShopifyCheckout */; };
+		6A8D64D42AF5635000FE4E4A /* PreloadBanner.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6A8D64D32AF5635000FE4E4A /* PreloadBanner.swift */; };
 		86250DE42AD5521C002E45C2 /* AppConfiguration.swift in Sources */ = {isa = PBXBuildFile; fileRef = 86250DE32AD5521C002E45C2 /* AppConfiguration.swift */; };
 /* End PBXBuildFile section */
 
@@ -43,6 +45,7 @@
 		4EF54F232A6F456B00F5E407 /* CartManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CartManager.swift; sourceTree = "<group>"; };
 		4EF54F262A6F4C4F00F5E407 /* CartViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CartViewController.swift; sourceTree = "<group>"; };
 		4EF54F2F2A6F63C000F5E407 /* CartViewController.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = CartViewController.xib; sourceTree = "<group>"; };
+		6A8D64D32AF5635000FE4E4A /* PreloadBanner.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PreloadBanner.swift; sourceTree = "<group>"; };
 		86250DE32AD5521C002E45C2 /* AppConfiguration.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppConfiguration.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -111,6 +114,7 @@
 				4EF54F262A6F4C4F00F5E407 /* CartViewController.swift */,
 				4EF54F2F2A6F63C000F5E407 /* CartViewController.xib */,
 				4EA7F9B42A9D2B9D003276A1 /* SettingsViewController.swift */,
+				6A8D64D32AF5635000FE4E4A /* PreloadBanner.swift */,
 			);
 			name = Application;
 			sourceTree = "<group>";
@@ -246,6 +250,7 @@
 				4EF54F242A6F456B00F5E407 /* CartManager.swift in Sources */,
 				4EBBA76F2A5F0CE200193E19 /* ProductViewController.swift in Sources */,
 				4EF54F272A6F4C4F00F5E407 /* CartViewController.swift in Sources */,
+				6A8D64D42AF5635000FE4E4A /* PreloadBanner.swift in Sources */,
 				4EBBA76B2A5F0CE200193E19 /* AppDelegate.swift in Sources */,
 				86250DE42AD5521C002E45C2 /* AppConfiguration.swift in Sources */,
 				4EBBA7AA2A5F124F00193E19 /* StorefrontClient.swift in Sources */,

Samples/MobileBuyIntegration/MobileBuyIntegration/PreloadBanner.swift

@@ -0,0 +1,84 @@
+/*
+MIT License
+
+Copyright 2023 - Present, Shopify Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+import UIKit
+
+class PreloadBanner {
+	static let shared = PreloadBanner()
+	private let bannerView: UIView
+	private let label: UILabel
+	private let height: CGFloat = 30
+	private let yVisible: CGFloat = UIScreen.main.bounds.height - 113
+	private let yHidden: CGFloat = UIScreen.main.bounds.height - 108
+
+	private init() {
+		bannerView = UIView(
+			frame: CGRect(
+				x: 0,
+				y: yHidden,
+				width: UIScreen.main.bounds.width,
+				height: height
+			)
+		)
+		bannerView.backgroundColor = .systemGreen
+		bannerView.isHidden = true
+		bannerView.alpha = 0
+
+		label = UILabel(frame: bannerView.bounds)
+		label.textAlignment = .center
+		label.textColor = .white
+		label.font = UIFont.systemFont(ofSize: 14)
+
+		bannerView.addSubview(label)
+
+		let firstConnectedScene = UIApplication.shared.connectedScenes.first
+
+		if let windowScene = firstConnectedScene as? UIWindowScene, let window = windowScene.windows.first {
+			window.addSubview(bannerView)
+		}
+	}
+
+	func showBanner(withText text: String) {
+		label.text = text
+
+		UIView.animate(withDuration: 0.3) {
+			self.bannerView.frame.origin.y = self.yVisible
+			self.bannerView.alpha = 1
+			self.bannerView.isHidden = false
+		}
+
+		// Schedule a timer to hide the banner after 3 seconds
+		DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
+			self.hideBanner()
+		}
+	}
+
+	func hideBanner() {
+		UIView.animate(withDuration: 0.3, animations: {
+			self.bannerView.frame.origin.y = self.yHidden
+			self.bannerView.alpha = 0
+		}, completion: {(_ completed) in
+			self.bannerView.isHidden = true
+		})
+	}
+}

Samples/MobileBuyIntegration/MobileBuyIntegration/ProductViewController.swift

@@ -25,8 +25,7 @@ import Buy
 import UIKit
 import ShopifyCheckout
 
-class ProductViewController: UIViewController {
-
+class ProductViewController: UIViewController, CheckoutEventListener {
 	// MARK: Properties
 
 	@IBOutlet private var image: UIImageView!
@@ -55,6 +54,12 @@ class ProductViewController: UIViewController {
 		title = "Browse"
 
 		tabBarItem.image = UIImage(systemName: "books.vertical")
+
+		ShopifyCheckout.events.addEventListener(self, for: .load)
+	}
+
+	deinit {
+		ShopifyCheckout.events.removeEventListener(self, for: .load)
 	}
 
 	// MARK: UIViewController Lifecycle
@@ -74,6 +79,15 @@ class ProductViewController: UIViewController {
 		reloadProduct()
 	}
 
+	func handleCheckoutEvent(_ event: CheckoutEvent, message: String? = nil) {
+		switch event {
+		case .load:
+			if ShopifyCheckout.configuration.preloading.enabled {
+				PreloadBanner.shared.showBanner(withText: "\(message ?? "")")
+			}
+		}
+	}
+
 	// MARK: Actions
 
 	@IBAction func addToCart() {

Samples/MobileBuyIntegration/MobileBuyIntegration/SceneDelegate.swift

@@ -27,6 +27,8 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
 
 	var window: UIWindow?
 
+	var preloadBanner: PreloadBanner?
+
 	func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options: UIScene.ConnectionOptions) {
 		guard let windowScene = (scene as? UIWindowScene) else { return }
 
@@ -47,6 +49,8 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
 		window.rootViewController = tabBarController
 		window.makeKeyAndVisible()
 
+		preloadBanner = PreloadBanner.shared
+
 		self.window = window
 	}
 }

Sources/ShopifyCheckout/CheckoutView.swift

@@ -116,6 +116,8 @@ extension CheckoutView: WKScriptMessageHandler {
 	}
 }
 
+private var timer: Date?
+
 extension CheckoutView: WKNavigationDelegate {
 	func webView(_ webView: WKWebView, decidePolicyFor action: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
 
@@ -161,18 +163,32 @@ extension CheckoutView: WKNavigationDelegate {
 		return .allow
 	}
 
-    func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
-        viewDelegate?.checkoutViewDidStartNavigation()
-    }
+	func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
+		timer = Date()
+		viewDelegate?.checkoutViewDidStartNavigation()
+	}
 
-    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
-        viewDelegate?.checkoutViewDidFinishNavigation()
+	func webView(_ webView: WKWebView, didFailProvisionalNavigation navigation: WKNavigation!, withError error: Error) {
+		timer = nil
 	}
 
-    func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {
-        CheckoutView.cache = nil
-        viewDelegate?.checkoutViewDidFailWithError(error: .sdkError(underlying: error))
-    }
+	func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
+		viewDelegate?.checkoutViewDidFinishNavigation()
+
+		if let startTime = timer {
+			let endTime = Date()
+			let diff = endTime.timeIntervalSince(startTime)
+			ShopifyCheckout.events.triggerEvent(.load, message: "Preloaded checkout in \(String(format: "%.2f", diff))s")
+		}
+
+		timer = nil
+	}
+
+	func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {
+		timer = nil
+		CheckoutView.cache = nil
+		viewDelegate?.checkoutViewDidFailWithError(error: .sdkError(underlying: error))
+	}
 
 	private func isExternalLink(_ action: WKNavigationAction) -> Bool {
 		if action.navigationType == .linkActivated && action.targetFrame == nil { return true }

Sources/ShopifyCheckout/ShopifyCheckout.swift

@@ -51,3 +51,37 @@ public func present(checkout url: URL, from: UIViewController, delegate: Checkou
 	viewController.presentationController?.delegate = rootViewController
 	from.present(viewController, animated: true)
 }
+
+public enum CheckoutEvent: Hashable {
+	case load
+}
+
+public protocol CheckoutEventListener: AnyObject {
+	func handleCheckoutEvent(_ event: CheckoutEvent, message: String?)
+}
+
+public var events = Events()
+
+public struct Events {
+	private var eventListeners = [CheckoutEvent: [CheckoutEventListener]]()
+
+	public mutating func addEventListener(_ listener: CheckoutEventListener, for event: CheckoutEvent) {
+		if eventListeners[event] == nil {
+			eventListeners[event] = [CheckoutEventListener]()
+		}
+		eventListeners[event]?.append(listener)
+	}
+
+	public mutating func removeEventListener(_ listener: CheckoutEventListener, for event: CheckoutEvent) {
+		eventListeners[event]?.removeAll { $0 === listener }
+	}
+
+	func triggerEvent(_ event: CheckoutEvent, message: String?) {
+		guard let listeners = eventListeners[event] else {
+			return
+		}
+		for listener in listeners {
+			listener.handleCheckoutEvent(event, message: message)
+		}
+	}
+}