How WeChat Pay’s C++ Cross‑Platform Framework Solved Mobile Payment Challenges

Background

WeChat Pay faced major issues due to separate iOS and Android implementations, including inconsistent bugs, poor scalability, incomplete data reporting, weak quality assurance, and inconsistent user experience.

iOS and Android implementations differed, leading to bugs and communication gaps.

Poor scalability made rapid business response difficult.

Quality assurance lacked unified testing and design knowledge.

User experience varied between platforms.

To address these core problems and technical debt, a C++ based cross‑platform framework was built, covering iOS from version 7.0.4 and Android from 7.0.7.

Online Metrics

Crash rate : Remained stable before and after launch, with no visible crashes for users.

Efficiency gain : The core payment flow required 3,512 lines of cross‑platform code versus 6,328 lines of native iOS code – a reduction of nearly 45%.

Feature development time dropped dramatically: the same cash‑register redesign that took a week on native iOS/Android was completed in 3‑5 person‑days with the cross‑platform solution.

What Is Software Architecture?

Architecture is defined here as the system’s components and their communication relationships, essentially the MVC/MVVM patterns that programmers work with daily.

Why Architecture Matters

Complex business requirements create inherent software complexity; managing this complexity through responsibility separation and modular design improves productivity.

Building the Cross‑Platform Architecture from Scratch

1. Abstract Business Flow

Traditional MVC/MVP/MVVM patterns do not handle business flow and view transitions well. We introduced a UseCase to encapsulate business logic and a UIPage to represent screens, allowing flow code to be centralized and reusable.

2. Add Routing Mechanism

We created a routing system that receives a data model, parses it, and triggers actions such as opening a UseCase, a UI page, a webview, a mini‑program, or a dialog. The routing data model combines a route type with the required parameters.

3. Manage Network Requests

Old architecture used a singleton network center with broadcast callbacks, causing one‑to‑many communication bugs and lifecycle issues. The new design treats each network request as an independent command object derived from BaseCgi, owned by a UseCase, ensuring a one‑to‑one lifecycle.

4. Standardize Data Transfer

We eliminated shared mutable models, switched to immutable value types, enforced one‑way data flow with dependency injection, and used the delegate pattern for necessary backward notifications. This removed data pollution and made data flow traceable.

Summary

The architecture’s essence is managing complexity arising from intricate payment business requirements. By abstracting use cases, introducing a routing layer, encapsulating network commands, and enforcing disciplined data handling, the cross‑platform framework dramatically reduces code size, accelerates feature delivery, improves stability, and provides a solid foundation for future payment innovations.