Hi-tech Singapore is planning to roll out a swarm of drones for tasks that include delivering parcels, inspecting buildings and providing security, but safety and privacy concerns mean the initiative may hit turbulence.Companies have already started testing the devices for commercial use, mainly in an area of over 200 hectares (500 acres) dotted with high-rise buildings and shopping malls, specially designated by the government for the trials.It is part of the affluent city's drive to em