Checking protocol conformance

It would be very useful to check whether an object conforms to a specific protocol or not. It's very useful when you have a list of objects, and only some of them conform to specific protocol. To check for protocol conformance, do the following:

class Rocket{ 
} 
var movingObjects = [Bicycle(name: "B1"), Car(name:"C1"), Rocket()] 
for item in movingObjects{ 
if let vehicle =  item as? VehicleProtocol{ 
print("Found vehcile with name \(vehicle.name)") 
vehicle.move() 
} 
else{ 
print("Not a vehcile") 
} 
} 

We created a list of objects, and some of them conform to VehicleProtocol that we created earlier. Inside the for-loop we casted each item to VehicleProtocol inside if statement; the cast will succeed only if this item already conforms to that protocol.