I. INTRODUCTION
A. Comparison and Our Contributions
B. Structure of The Survey
II. BACKGROUND TECHNOLOGIES
A. Federated Learning
B. Internet of Things
C. Visions of the Use of FL in IoT
III. FL FOR IOT SERVICES
IV. FL FOR IOT APPLICATIONS
V. LESSONS LEARNED
A. Lessons Learned from FL-IoT Services
B. Lessons Learned from FL-IoT Applications
VI. RESEARCH CHALLENGES AND DIRECTIONS
VII. CONCLUSIONS