Hiring a dedicated mobile app developer as a freelancer is a great idea for ensuring focused attention on your project. Here are some suggestions:

1. **Freelance Platforms**: Websites like Upwork, Freelancer, and Toptal are popular platforms where you can find experienced mobile app developers for hire. You can browse through profiles, review portfolios, and conduct interviews to find the right fit.

2. **Networking**: Reach out to your professional network, attend industry events, or join relevant online communities where you can connect with talented developers who may be open to freelancing opportunities.

3. **Job Boards**: Posting your job requirements on specialized job boards like We Work Remotely, Remote.co, or Stack Overflow Jobs can help you attract qualified mobile app developers who are looking for freelance work.

4. **Social Media**: Utilize platforms like LinkedIn, Twitter, or Facebook to announce your job opening and connect with potential candidates. You can also join groups or communities related to mobile app development to find freelancers.

5. **Referrals**: Ask for recommendations from colleagues, friends, or other business owners who have previously hired freelance developers. Personal referrals can often lead to finding reliable and skilled professionals.

6. **Technical Evaluation**: When interviewing candidates, consider conducting technical assessments or asking for sample projects to evaluate their skills and expertise in mobile app development.

7. **Contract and Communication**: Clearly define the terms of the contract, including payment structure, project milestones, and communication channels. Establishing effective communication from the outset is crucial for successful collaboration.