Well, I generally use to ask this questions in interviews :)

Although I don't know Swift but I can give you a general idea about to achieve this.

You have to play with some trigonometry to get current direction vector according to your current angle.

Here is the pseudo code.

 float speed = 0.01
 
 void GameLoop()
 {
 // I don't know that how Vector2 works at your end, but I hope you will get this.
 Vector2 currentPosition = currentPositionOfObject;
 float currentAngle = currentAngleOfObject;
 float directionX = Cos (currentAngle); // check if your Cos method takes angle in radians of degrees.
 float directionY = Sin (currentAngle); // check if your Sin method takes angle in radians of degrees.
 
 Vector2 newPosition = (currentPosition.x + (directionX * speed),currentPosition.y + (directionY * speed));
 currentPositionOfObject = newPosition;
 }

I have already answered the same question but in Unity (C#) [here](https://gamedev.stackexchange.com/questions/114733/giving-to-object-velocity-to-the-direction-it-facing-unity/114734#114734). Just for reference if you want more details.