Consolidate PayPal ViewControllers (#1102)

* Consolidate PayPal Checkout, Vault and Pay Later ViewControllers into a single ViewController with all 3 buttons
* Update settings drop down to PayPal - Web Checkout

Demo/Application/Base/Settings/Settings.bundle/Root.plist

@@ -18,9 +18,7 @@
 			<key>Titles</key>
 			<array>
 				<string>PayPal - Native Checkout</string>
-				<string>PayPal - Vault</string>
-				<string>PayPal - Checkout</string>
-				<string>PayPal - Pay Later</string>
+				<string>PayPal - Web Checkout</string>
 				<string>Credit Card Tokenization</string>
 				<string>Venmo - Custom Button</string>
 				<string>Apple Pay - PassKit</string>
@@ -33,9 +31,7 @@
 			<key>Values</key>
 			<array>
 				<string>BraintreeDemoPayPalNativeCheckoutViewController</string>
-				<string>BraintreeDemoPayPalVaultViewController</string>
-				<string>BraintreeDemoPayPalCheckoutViewController</string>
-				<string>BraintreeDemoPayPalPayLaterViewController</string>
+				<string>BraintreeDemoPayPalWebCheckoutViewController</string>
 				<string>BraintreeDemoCardTokenizationViewController</string>
 				<string>BraintreeDemoVenmoViewController</string>
 				<string>BraintreeDemoApplePayPassKitViewController</string>

Demo/Application/Features/PayPal - Web Checkout/BraintreeDemoPayPalWebCheckoutViewController.swift

@@ -0,0 +1,93 @@
+import Foundation
+import UIKit
+import BraintreePayPal
+
+class BraintreeDemoPayPalWebCheckoutViewController: BraintreeDemoPaymentButtonBaseViewController {
+
+    lazy var payPalClient = BTPayPalClient(apiClient: apiClient)
+
+    override func createPaymentButton() -> UIView! {
+        let payPalCheckoutButton = paymentButton(title: "PayPal Checkout", action: #selector(tappedPayPalCheckout))
+        let payPalVaultButton = paymentButton(title: "PayPal Vault", action: #selector(tappedPayPalVault))
+        let payPalPayLaterButton = paymentButton(title: "PayPal with Pay Later Offered", action: #selector(tappedPayPalPayLater))
+
+        let buttons = [payPalCheckoutButton, payPalVaultButton, payPalPayLaterButton]
+        let stackView = UIStackView(arrangedSubviews: buttons)
+        stackView.axis = .vertical
+        stackView.alignment = .center
+        stackView.distribution = .fillEqually
+        stackView.translatesAutoresizingMaskIntoConstraints = false
+
+        return stackView
+    }
+
+    @objc func tappedPayPalCheckout(_ sender: UIButton) {
+        progressBlock("Tapped PayPal - Checkout using BTPayPalClient")
+        sender.setTitle("Processing...", for: .disabled)
+        sender.isEnabled = false
+
+        let request = BTPayPalCheckoutRequest(amount: "4.30")
+
+        payPalClient.tokenize(request) { nonce, error in
+            sender.isEnabled = true
+
+            guard let nonce else {
+                self.progressBlock(error?.localizedDescription)
+                return
+            }
+
+            self.completionBlock(nonce)
+        }
+    }
+
+    @objc func tappedPayPalVault(_ sender: UIButton) {
+        progressBlock("Tapped PayPal - Vault using BTPayPalClient")
+        sender.setTitle("Processing...", for: .disabled)
+        sender.isEnabled = false
+
+        let request = BTPayPalVaultRequest()
+
+        payPalClient.tokenize(request) { nonce, error in
+            sender.isEnabled = true
+
+            guard let nonce else {
+                self.progressBlock(error?.localizedDescription)
+                return
+            }
+
+            self.completionBlock(nonce)
+        }
+    }
+
+    @objc func tappedPayPalPayLater(_ sender: UIButton) {
+        progressBlock("Tapped PayPal - initiating with Pay Later offered")
+        sender.setTitle("Processing...", for: .disabled)
+        sender.isEnabled = false
+
+        let request = BTPayPalCheckoutRequest(amount: "4.30")
+        request.offerPayLater = true
+
+        payPalClient.tokenize(request) { nonce, error in
+            sender.isEnabled = true
+
+            guard let nonce else {
+                self.progressBlock(error?.localizedDescription)
+                return
+            }
+
+            self.completionBlock(nonce)
+        }
+    }
+
+    // TODO: move into a shared class once the base ViewControllers are converted to Swift
+    func paymentButton(title: String, action: Selector) -> UIButton {
+        let button = UIButton(type: .system)
+        button.setTitle(title, for: .normal)
+        button.setTitleColor(.blue, for: .normal)
+        button.setTitleColor(.lightGray, for: .highlighted)
+        button.setTitleColor(.lightGray, for: .disabled)
+        button.translatesAutoresizingMaskIntoConstraints = false
+        button.addTarget(self, action: action, for: .touchUpInside)
+        return button
+    }
+}