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updated sequence diagrams
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mmroz committed Aug 14, 2024
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92 changes: 70 additions & 22 deletions docs/src/getting-started/cash-app-pay-v3.md
Original file line number Diff line number Diff line change
@@ -1,13 +1,16 @@
---
layout: default
title: Cash App Pay
title: Cash App Pay with Checkout V3
parent: Getting Started
nav_order: 4
nav_order: 5
---

# Cash App Pay
{: .d-inline-block .no_toc }
NEW (v5.3.0)
{: .label .label-green }


<details markdown="block">
<summary>
Table of contents
Expand All @@ -16,47 +19,71 @@ NEW (v5.3.0)
- TOC
{:toc}
</details>


{: .alert }
> Cash App Pay is currently available in the following region(s): US
With our latest enhancements, you can now support taking Cash App Pay payments using your Afterpay merchant account. To do this, you must generate a token by sending a server-to-server call to the [Afterpay API Create Checkout endpoint][afterpay-create-checkout-endpoint]{:target="_blank"} with a parameter of `isCashAppPay` set to `true`. This method requires importing and implementing the Cash App PayKit SDK.
This method requires importing and implementing the Cash App PayKit SDK.

{: .info }
> When creating a checkout token, you must set both `redirectConfirmUrl` and `redirectCancelUrl`. If they are not set, an error will be returned from the server and the SDK will ouput a malformed JSON error. The SDK’s example merchant server sets the parameters [here][example-server-props]{:target='_blank'}. See more details at [Redirect Method][api-reference-props]{:target='_blank'} in the Standard Checkout API.
>, you must set both `redirectConfirmUrl` and `redirectCancelUrl`. If they are not set, an error is returned from the server and the SDK will outputs a malformed JSON error.
## Step 1: Install the Cash App Pay Kit SDK

### Installation (Option One): SPM
You can install Pay Kit via SPM. Create a new Xcode project and navigate to `File > Swift Packages > Add Package Dependency`. Enter the URL `https://github.com/cashapp/cash-app-pay-ios-sdk` and tap **Next**. Choose the `main` branch, and on the next screen, download the required packages.

### Installation (Option Two): Cocoapods
Add Cocoapods to your project. Open the `Podfile` and add `pod 'CashAppPayKit'` and/or `pod 'CashAppPayKitUI'` and save your changes. Run `pod update` and Pay Kit will now be included through Cocoapods.

## Step 2: Implement the Cash App Pay Observer Protocol

To receive updates from Pay Kit, you’ll need to implement the Cash App Pay Observer protocol. Your checkout view controller can conform to this protocol, or you can create a dedicated observer class.

The `CashAppPayObserver` protocol contains only one method:

``` swift
func stateDidChange(to state: CashAppPaySDKState) {
// handle state changes
}
```

### States

Your implementation should switch on the `state` parameter and handle the appropriate state changes. Some of these possible states are for information only, but most drive the logic of your integration. The most critical states to handle are listed in the table below:

| State | Description |
|:------|:------------|
| `ReadyToAuthorize` | Show a Cash App Pay button in your UI and call `authorizeCustomerRequest()` when it is tapped. |
| `Approved` | Grants are ready for your backend to use to create a payment. |
| `Declined` | Customer has declined the Cash App Pay authorization and must start the flow over or choose a new payment method. |

### Error States

| State | Description |
|:------|:------------|
| `.integrationError` | A fixable bug in your integration. |
| `.apiError` | A degradation of Cash App Pay server APIs. Your app should temporarily hide Cash App Pay functionality. |
| `.unexpectedError` | A bug outside the normal flow. Report this bug (and what caused it) to Cash App Developer Support. |

{: .info }
> You must update your UI in response to these state changes.
## Step 3: Implement URL handling
To use Pay Kit iOS, Cash App must be able to call a URL that will redirect back to your app. The simplest way to accomplish this is via [Custom URL Schemes][custom-url-schemes], but if your app supports [Universal Links][universal-links] you may use those URLs as well.

To use PayKit iOS, Cash App must be able to call a URL that will redirect back to your app. The simplest way to accomplish this is via [Custom URL Schemes][custom-url-schemes], but if your app supports [Universal Links][universal-links] you may use those URLs as well.

Choose a unique scheme for your application and register it in Xcode from the **Info** tab of your application’s Target.

You’ll pass a URL that uses this scheme (or a Universal Link your app handles) into the `createCustomerRequest()` method that starts the authorization process.

When your app is called back by Cash App, simply post the `CashAppPay.RedirectNotification` from your `AppDelegate` or `SceneDelegate`, and the SDK will handle the rest:

``` swift
import UIKit
import PayKit

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
if let url = URLContexts.first?.url {
Expand All @@ -69,8 +96,11 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
}
}
```

To set the v3 Configuration, use the settings in the code examples below.

1. Set the configuration as follows:

```swift
Afterpay.setV3Configuration(
CheckoutV3Configuration(
Expand All @@ -80,7 +110,9 @@ Afterpay.setV3Configuration(
)
)
```

2. Call "begin the checkout" and store the results:

```swift
Afterpay.checkoutV3WithCashAppPay(
consumer: Consumer(email: "[email protected]"),
Expand All @@ -98,14 +130,20 @@ Afterpay.checkoutV3WithCashAppPay(
}
}
```

## Step 4: Instantiate Pay Kit iOS

When you’re ready to authorize a payment using Cash App Pay,

1. Instantiate the SDK with the Afterpay Pay Kit Client ID via `Afterpay.cashAppClientId`.
2. The SDK defaults to point to the production endpoint; for development, set the endpoint to `.sandbox`.
3. Add your observer to the Pay Kit SDK.

{: .note }
> Ensure that the Afterpay SDK is configured per the [instructions][afterpay-configuration] before attempting to access `Afterpay.cashAppClientId`.
For example, from your checkout view controller that implements the `PayKitObserver` protocol, you might instantiate the SDK to be:

``` swift
private let sandboxClientID = Afterpay.cashAppClientId
private lazy var sdk: CashAppPay = {
Expand All @@ -115,9 +153,13 @@ private lazy var sdk: CashAppPay = {
}()
```
## Step 5: Create a Customer Request

You can create a customer request as soon as you know the amount you’d like to charge or if you'd like to create an on-file payment request. You must create this request as soon as your checkout view controller loads, so that your customer can authorize the request without delay.

### Step 5A: Sign the Order Token

After retrieving the token from your server-to-server call, the order must be signed, so that you can retrieve the JWT and associated data. This might look like the following example:

``` swift
let token = retrieveTokenFromServerToServerCall()
Afterpay.signCashAppOrderToken(token) { result in
Expand All @@ -130,8 +172,11 @@ Afterpay.signCashAppOrderToken(token) { result in
}
}
```

### Step 5B: Create a Pay Kit Customer Request

To charge a one-time payment, your **Create Request** call might look like this (in the following example, `cashData` is the response object that is returned in the `didCommenceCheckout` parameter from step 5A):

``` swift
paykit.createCustomerRequest(
params: CreateCustomerRequestParams(
Expand All @@ -151,21 +196,32 @@ paykit.createCustomerRequest(
)
)
```

Your Observer’s state will change to `.creatingCustomerRequest`, then `.readyToAuthorize` with the created `CustomerRequest` struct as an associated value.

## Step 6: Authorize the Customer Request

### Step 6A: Add an Authorize Request Event to Cash App Pay button

Once the SDK is in the `.readyToAuthorize` state, you can store the associated `CustomerRequest` and display a Cash App Pay button. When the Customer taps the button, you can authorize the customer request. See [CashAppPayButton][cash-button]{:target='_blank'} to learn more about the Cash App Pay button component.

**Example**

``` swift
@objc func cashAppPayButtonTapped() {
sdk.authorizeCustomerRequest(request)
}
```

Your app will redirect to Cash App for authorization. When the authorization is completed, your redirect URL will be called and the `RedirectNotification` will post. Then, the SDK will fetch your authorized request and return it to your Observer, as part of the change to the `.approved` state.

### Step 6B: Validate the Cash App Pay Order

{: .alert }
This step must not be skipped

Back in Afterpay, confirm the order and confirm the payment:

```swift
Afterpay.checkoutV3ConfirmForCashAppPay(
token: checkoutV3.token,
Expand All @@ -182,8 +238,12 @@ Afterpay.checkoutV3ConfirmForCashAppPay(
}
}
```


## Sequence Diagram

The below diagram describes the happy path.

``` mermaid
%%{
init: {
Expand All @@ -199,11 +259,11 @@ The below diagram describes the happy path.
}
}
}%%
sequenceDiagram
participant App
participant Afterpay SDK
participant Cash App Pay SDK
participant Proxy Server
participant Afterpay API
Note over App,Afterpay API: Setup
App->>Afterpay SDK: Configure the SDK
Expand All @@ -212,27 +272,15 @@ sequenceDiagram
Note over App,Cash App Pay SDK: Ensure same environment<br>as Afterpay SDK config
App->>App: Implement<br>deep linking
App->>Cash App Pay SDK: Register for state updates
App->>Afterpay SDK: Create a Checkout
Afterpay SDK->>Afterpay API: Creates a Vistual Card
Afterpay API-->>App: Checkout result with <br> Single Use Payment Card
Note over App,Afterpay API: Create Customer Request and Capture
App->>Proxy Server: Get Token Request
Proxy Server->>Afterpay API: Create Checkout Request
Note over Proxy Server,Afterpay API: Ensure same environment<br>as Afterpay SDK config<br><br>Request body should<br>contain `isCashAppPay: true`
Afterpay API-->>Proxy Server: Create Checkout Response
Note over Afterpay API,Proxy Server: Body contains a token
Proxy Server-->>App: Get Token Response
App->>Afterpay SDK: Sign the token
Afterpay SDK->>Afterpay API: Token signing request
Afterpay API-->>Afterpay SDK: Token signing response
Afterpay SDK-->>App: Decoded token data
App->>Cash App Pay SDK: Create a customer request
App->>Cash App Pay SDK: Authorize the customer request
App->>Afterpay SDK: Validate the order
App->>Proxy Server: Upon approved state send capture request
Note over App,Proxy Server: Pass the Grant Id (from the approved state)<br>and token in the body
Proxy Server->>Afterpay API: Capture Payment Request
Afterpay API-->>Proxy Server: Capture Payment Response
Proxy Server-->>App: Capture Payment Respnse
App->>App: Handle payment<br>capture response
```

[custom-url-schemes]: https://developer.apple.com/documentation/xcode/defining-a-custom-url-scheme-for-your-app
[universal-links]: https://developer.apple.com/ios/universal-links/
[afterpay-configuration]: ../configuration
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