iOS Productivity App Development

I'm looking for an experienced mobile app developer to create a productivity app for iOS. The primary purpose of the app is to enhance productivity through collaboration tools.

Key Requirements:
- The app must be built for iOS.
- The app should include robust collaboration tools.

Ideal Skills and Experience:
- Proven experience in developing iOS apps.
- Strong understanding of productivity app features, especially collaboration tools.
- Proficiency in Swift and Objective-C.
- Familiarity with Apple's Human Interface Guidelines.
- Excellent UI/UX design skills.
- Strong problem-solving abilities and attention to detail.

Please provide your portfolio and relevant experience. Looking forward to your bids!