Swift equivalent of this ActionScript function - ios

Question

I translated this tutorial on BSP into swift. In the tutorial there's this ActionScript function.
public function getRoom():Rectangle
{
// iterate all the way through these leafs to find a room, if one exists.
if (room != null)
return room;
else
{
var lRoom:Rectangle;
var rRoom:Rectangle;
if (leftChild != null)
{
lRoom = leftChild.getRoom();
}
if (rightChild != null)
{
rRoom = rightChild.getRoom();
}
if (lRoom == null && rRoom == null)
return null;
else if (rRoom == null)
return lRoom;
else if (lRoom == null)
return rRoom;
else if (FlxG.random() > .5)
return lRoom;
else
return rRoom;
}
}
I translated this function into Swift (to the best of my ability) I must have written it wrong because the function is returning a nil value when it shouldn't be.
My version in Swift:
// left/right child are initialized as follows:
// leftChild:Room?
// rightChild:Room?
public func getRoom() -> Room? {
if room != nil {
return room
} else {
var lRoom:Room?
var rRoom:Room?
if leftChild != nil {
lRoom = leftChild!.getRoom()!
}
if rightChild != nil {
rRoom = rightChild!.getRoom()!
}
if lRoom == nil && rRoom == nil {
return nil
} else if rRoom == nil {
return lRoom
} else if lRoom == nil {
return rRoom
} else if Double.random(in: 0..<1.0) > 0.5 {
return lRoom
} else {
return rRoom
}
}
}
Where Room is a basic class I made to help me handle the rooms.
class Room {
var x1:Int
var x2:Int
var y1:Int
var y2:Int
var center:CGPoint
init(X: Int, Y: Int, W: Int, H: Int) {
x1 = X
x2 = X + W
y1 = Y
y2 = Y + H
center = CGPoint(x: (x1 + x2) / 2, y: (y1 + y2) / 2)
}
}
I'm getting a nil value when I shouldn't be. I think I translated the function wrong. Rectangle would be CGRect in Swift but I replaced it with my Room class in other places in the code, so I know it'll work with the Room class here.
How would this function be written in Swift?

Answer 1

Your problem is that you are force unwrapping the result of getRoom - This function returns an optional and can legitimately return nil when your traversal hits a leaf node. Force unwrapping nil results in a crash
By using conditional unwrapping correctly you can not only make your code more readable, you can eliminate the crash.
public func getRoom() -> Room? {
if let _ = room {
return room
}
let lRoom = leftChild?.getRoom()
let rRoom = rightChild?.getRoom()
switch (lRoom != nil, rRoom != nil) {
case (false,false):
return nil
case (true,false):
return lRoom
case (false,true):
return rRoom
case (true,true):
return arc4random_uniform(2) == 1 ? lRoom: rRoom
}
}