Add backgroundColor to configuration (#41)

* Add backgroundColor to configuration

* Update README

README.md

@@ -98,7 +98,7 @@ ShopifyCheckout.configuration.colorScheme = .web
 ```
 
 #### `spinnerColor`
-If the checkout session is not ready and being initialized, a loading spinner is shown and can be customized via `spinnerColor` property:
+If the checkout session is not ready and being initialized, a loading spinner is shown and can be customized via the `spinnerColor` property:
 
 ```swift
 // Use a custom UI color
@@ -109,6 +109,17 @@ ShopifyCheckout.configuration.spinnerColor = .systemBlue
 ```
 _Note: use preloading to optimize and deliver an instant buyer experience._
 
+#### `backgroundColor`
+While the checkout session is being initialized, the background color of the view can be customized via the `backgroundColor` property:
+
+```swift
+// Use a custom UI color
+ShopifyCheckout.configuration.backgroundColor = UIColor(red: 0.09, green: 0.45, blue: 0.69, alpha: 1.00)
+
+// Use a system color
+ShopifyCheckout.configuration.backgroundColor = .systemBackground
+```
+
 ### Preloading
 Initializing a checkout session requires communicating with Shopify servers and, depending on the network weather and the quality of the buyer's connection, can result in undesirable waiting time for the buyer. To help optimize and deliver the best experience, the SDK provides a preloading hint that allows app developers to signal and initialize the checkout session in the background and ahead of time.
 

Samples/MobileBuyIntegration/MobileBuyIntegration/SettingsViewController.swift

@@ -155,6 +155,7 @@ class SettingsViewController: UITableViewController {
 			let newColorScheme = colorScheme(at: indexPath)
 			ShopifyCheckout.configuration.colorScheme = newColorScheme
 			ShopifyCheckout.configuration.spinnerColor = newColorScheme.spinnerColor
+			ShopifyCheckout.configuration.backgroundColor = newColorScheme.backgroundColor
 			view?.window?.overrideUserInterfaceStyle = newColorScheme.userInterfaceStyle
             tableView.reloadSections(IndexSet(integer: Section.colorScheme.rawValue), with: .automatic)
 		default:
@@ -237,11 +238,20 @@ extension Configuration.ColorScheme {
 	}
 
 	var spinnerColor: UIColor {
-		switch ShopifyCheckout.configuration.colorScheme {
+		switch self {
 		case .web:
 			return UIColor(red: 0.18, green: 0.16, blue: 0.22, alpha: 1.00)
 		default:
 			return UIColor(red: 0.09, green: 0.45, blue: 0.69, alpha: 1.00)
 		}
 	}
+
+	var backgroundColor: UIColor {
+		switch self {
+		case .web:
+			return UIColor(red: 0.94, green: 0.94, blue: 0.91, alpha: 1.00)
+		default:
+			return .systemBackground
+		}
+	}
 }

Sources/ShopifyCheckout/CheckoutViewController.swift

@@ -76,7 +76,7 @@ class CheckoutViewController: UIViewController, UIAdaptivePresentationController
 	override public func viewDidLoad() {
 		super.viewDidLoad()
 
-		view.backgroundColor = .systemBackground
+		view.backgroundColor = ShopifyCheckout.configuration.backgroundColor
 
 		view.addSubview(checkoutView)
 		NSLayoutConstraint.activate([

Sources/ShopifyCheckout/Configuration.swift

@@ -41,6 +41,8 @@ public struct Configuration {
 
 	public var spinnerColor: UIColor = UIColor(red: 0.09, green: 0.45, blue: 0.69, alpha: 1.00)
 
+	public var backgroundColor: UIColor = .systemBackground
+
 }
 
 extension Configuration {