> For the complete documentation index, see [llms.txt](https://docs.payments.thalescloud.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.payments.thalescloud.io/nfc-wallet-sdk-ios/implement-nfc-wallet/make-payments/implement-contactless-payment.md).

# Implement contactless payment

## Overview

The NFC Wallet SDK supports multiple contactless payment entry points on iOS:

* **Double-click**: The end user double-clicks the device side button to open the default digital wallet application.
* **Field detect**: The end user brings the device close to a point-of-sale (POS) terminal. When iOS detects an NFC field, it opens the default digital wallet application.
* **Manual mode**: The end user opens your digital wallet application and starts a payment from the in-app UI.

Choose the experience that matches your digital wallet application UX.

## User experience

### Double-click

<div align="center"><figure><img src="/files/DVeWIg8tobbMzFsVNK3V" alt="" width="563"><figcaption><p>Double-click experience (side / lock button).</p></figcaption></figure></div>

The end user presses the device side / lock button twice. The OS then launches the default digital wallet application. The application displays the default digital card for payment.

{% hint style="info" %}
To support **double-click**, the end user must set your digital wallet application as the default contactless payment application in iOS Settings.
{% endhint %}

### Field detect

<div align="center"><figure><img src="/files/6YSXhUzNm6X93RPG9tzb" alt="" width="563"><figcaption><p>Field detect experience (NFC field detection).</p></figcaption></figure></div>

The end user brings the device near a POS terminal. When the NFC field is detected, the OS launches the default digital wallet application. The application displays the default digital card for payment.

{% hint style="info" %}
To support **field detect**, the end user must set your digital wallet application as the default contactless payment application in iOS Settings.
{% endhint %}

### Manual mode

<figure><img src="/files/7sBTg0jUIwigCtBTFKba" alt=""><figcaption><p>Manual mode experience (in-app payment start).</p></figcaption></figure>

In this experience, the end user starts the payment from within your digital wallet application. You implement the UI and the action that triggers the payment flow.

### Common payment flow

<figure><img src="/files/QfNsAYHKbeA0e8xca3AF" alt=""><figcaption><p>Common contactless payment flow.</p></figcaption></figure>

Whatever triggers the payment, the flow is typically:

1. The end user initiates a payment (select pay button).
2. The end user authenticates (**CDCVM**).
3. iOS presents the **NFC modal UI** inviting end user to TAP.
4. The end user taps the device on the POS terminal.
5. After a successful tap:
   * iOS shows a success state.
   * Your digital wallet application can display the **transaction context**.
6. Your digital wallet application receives the authorization result (approved/declined) and displays it to the end user (**transaction notification**)

## Implementation guides

After you choose the contactless payment experience for your digital wallet application, implement contactless payment in this order:

1. [Check prerequisites](/nfc-wallet-sdk-ios/implement-nfc-wallet/make-payments/implement-contactless-payment/1.-check-prerequisites.md)

   including the Apple HCE entitlement
2. [Manage the default payment application](/nfc-wallet-sdk-ios/implement-nfc-wallet/make-payments/implement-contactless-payment/2.-manage-the-default-payment-application.md)
3. [Manage `NFCPresentmentIntentAssertion`](/nfc-wallet-sdk-ios/implement-nfc-wallet/make-payments/implement-contactless-payment/3.-manage-nfcpresentmentintentassertion.md)
4. [Implement payment](/nfc-wallet-sdk-ios/implement-nfc-wallet/make-payments/implement-contactless-payment/4.-implement-payment.md)
5. [Display the transaction context](/nfc-wallet-sdk-ios/implement-nfc-wallet/make-payments/implement-contactless-payment/5.-display-the-transaction-context.md)

For an end-to-end walkthrough, see the [full implementation example](/nfc-wallet-sdk-ios/implement-nfc-wallet/make-payments/implement-contactless-payment/full-implementation-example.md).

{% hint style="warning" %}
**Apple HCE entitlement**: When submitting your digital wallet application to the App Store or TestFlight, provide the following:

* Access to a pre-release TestFlight build of your issuer application.
* Test login credentials.
* At least one test payment credential that can be provisioned and used to perform an NFC transaction.
* Screenshots or a video of an NFC transaction at a terminal.
* A video demonstrating your implementation of the Presentment Intent Assertion API.

Refer to [HCE-based contactless transactions for apps in the European Economic Area (EEA)](https://developer.apple.com/support/hce-transactions-in-apps/) for more details.
{% endhint %}


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