I'm looking for an experienced iOS developer to create an e-commerce app. Essential features: - User authentication - Payment gateway integration (PayPal, WeChat Pay, Alipay, Card Payment) - Comprehensive product catalog Ideal candidates should have: - Proven experience in developing secure and user-friendly e-commerce apps - Strong knowledge of integrating multiple payment gateways - Expertise in implementing robust user authentication systems - A solid portfolio showcasing similar projects Please share relevant experience and approach.