Can't make number negative

I have this swift code:

x = Float(arc4random_uniform(30))
y = Float(arc4random_uniform(30))
z = Float(arc4random_uniform(30))
coords.x = 0.00 - x
coords.y = 0.00 - y
coords.z = 0.00 - z

print("\(coords.x)       \(coords.y)         \(coords.z)      xyz")

For some reason it always outputs the numbers as positive, I have also tried:

x = -Float(arc4random_uniform(30))
y = -Float(arc4random_uniform(30))
z = -Float(arc4random_uniform(30))
coords.x = x
coords.y = y
coords.z = z

and...

x = -1 * Float(arc4random_uniform(30))
y = -1 * Float(arc4random_uniform(30))
z = -1 * Float(arc4random_uniform(30))
coords.x = x
coords.y = y
coords.z = z

...and even one more where I had to cast the random number as an Int to multiply it by -1 within the Float cast.

x = Float(arc4random_uniform(30))
y = Float(arc4random_uniform(30))
z = Float(arc4random_uniform(30))
coords.x = 0.00 - x
coords.y = 0.00 - y
coords.z = 0.00 - z

The console output is always something like:

24.0       27.0         29.0      xyz

...no negative numbers.

What am I doing wrong?