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This guide explains how a merchant mobile app or H5 page can launch supported bank apps to complete FPS App-to-App payments. QFPay provides payment parameters via API. Your application then opens the user’s banking app using platform-specific methods. After payment, the result is returned via callback or backend verification. Android and iOS platforms are supported.

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Integration Overview

Choose the flow that matches your application architecture:
PlatformFlow TypeUsage ScenarioLaunch Method
AndroidNative AppApp directly triggers FPS paymentIntent to bank app
AndroidH5 to AppWebView triggers FPS paymentJSBridge + Intent
iOSNative AppApp directly triggers FPS paymentUIActivityViewController
iOSH5 to AppWKWebView triggers FPS paymentWKWebView + JSBridge
For all flows:
  1. Retrieve payment parameters via API
  2. Launch the FPS bank app
  3. Receive callback or verify payment status
Fps App Call App En

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1. Retrieve Payment Parameters

Endpoint POST /trade/v1/payment PayType: 802010

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Request Parameters

ParameterRequiredTypeDescription
pay_typeYesStringFixed value 800210
txamtYesIntAmount in cents (100 = HKD 1.00)
txdtmYesStringFormat: YYYY-MM-DD hh:mm:ss
out_trade_noYesStringUnique merchant order reference
…——See Common Parameters
If your FPS integration is via HSBC direct channel, you must obtain a dedicated SSL certificate matching your merchant legal name.This is required for:• secure callbacks (Universal Links / HTTPS redirects)
• HSBC certification & production onboardingSee the FPS e-Cert setup guide for details.

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Response Parameters

NameDescription
Common Response FieldsSee response format documentation
pay_paramsURL used to launch the FPS payment app

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2. Android FPS Payment Flow

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2.1 Native App-to-App Flow

This flow launches the banking app directly using an Android Intent.
  1. Retrieve pay_params from API
  2. Launch bank app using Intent
  3. Receive result via onActivityResult
  4. Verify final status via backend
Android Example 
int REQUEST_CODE = 100;
String payUrl = "PAYMENT_URL_FROM_API";

Intent intent = new Intent("hk.com.hkicl");
intent.putExtra("url", payUrl);

startActivityForResult(intent, REQUEST_CODE);

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_CODE) {
        if (resultCode == RESULT_OK) {
            // Payment initiated
        } else if (resultCode == RESULT_CANCELED) {
            // User cancelled or failed
        }
    }
}

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2.2 Android H5-to-App (WebView)

Used when an H5 page inside WebView launches the FPS app. Flow
  1. Enable JavaScript in WebView
  2. Register JS bridge
  3. H5 sends payment URL to Android
  4. Android launches bank app
  5. Return result to H5
  6. Verify payment via backend
H5 example: 
AndroidBridge.handleMessage(JSON.stringify({
  url: "PAYMENT_URL_FROM_API"
}));

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3. iOS FPS Payment Flow

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3.1 Native App-to-App Flow

iOS uses UIActivityViewController and App Extensions to launch bank apps. Flow
  1. Retrieve payment URL
  2. Launch bank app via extension
  3. User completes payment
  4. App receives Universal Link callback
  5. Verify status via backend

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Key Steps

• Create NSExtensionItem
• Package payment URL & callback URL
• Use type identifier: hk.com.hkicl
• Present UIActivityViewController 
let paymentPayload = [
    "URL": paymentURL,
    "callback": "https://your-domain.com/callback"
]

let itemProvider = NSItemProvider(
    item: paymentPayload as NSDictionary,
    typeIdentifier: "hk.com.hkicl"
)

let extensionItem = NSExtensionItem()
extensionItem.attachments = [itemProvider]

let activityVC = UIActivityViewController(
    activityItems: [extensionItem],
    applicationActivities: nil
)

present(activityVC, animated: true)

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3.2 iOS H5-to-App via WKWebView

Used when FPS payment is triggered from an H5 page. Flow
  1. H5 retrieves payment URL
  2. H5 calls native app via JSBridge
  3. Native launches bank app
  4. Native returns result to H5
  5. Backend verifies final payment
Bridge call example: 
window.webkit.messageHandlers.NativeBridge.postMessage({
  action: "FPSH5CallApp",
  params: { paymentRequestURL: "PAYMENT_URL_FROM_API" },
  callbackId: "callback_123"
});

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Error Handling & Fallbacks

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Result Codes

CodeMeaning
RESULT_OKPayment app launched successfully
RESULT_CANCELEDCancelled, failed, or timeout
Always verify payment using your backend order query.

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If FPS App Is Not Installed

If no supported bank app is available: • show an error message
• provide fallback QR payment
• allow retry

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Callback Failure

If callback or redirect fails: • inform user payment is verifying
• re-query backend after 3–5 seconds
• display loading or retry option

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Demo Downloads

PlatformFlowDemo
AndroidNative & WebViewDownload
iOSNative (Obj-C)https://img-int.qfapi.com/upstatic/20251120c100/FPSDemo/FPSElement.zip
iOSNative (Swift)https://img-int.qfapi.com/upstatic/20251120c100/FPSDemo/FPSElementDemo.zip
iOSJSBridgehttps://img-int.qfapi.com/upstatic/20251120c100/FPSDemo/fps-bridge.zip