this question of mine is related to the topic acceleration.

For an object to have uniform motion or for it to move with constant velocity, the magnitude and direction of its velocity  both have to remain unchanged.

i) while swinging the velocity is not the same at all instants, at the highest point of its swing the velocity becomes zero.

ii) the direction of the swing reverses after half a swing, so the body does not move in the same direction all throughout its motion.

So the motion of the swing is accelerated. However if the car moves on a straight road with a constant velocity of 100km/h then its motion is uniform.