Clamp node to screen bounds - sprite-kit

Question

override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {
for touch: AnyObject in touches {
let location = touch.locationInNode(self)
let previousLocation = touch.previousLocationInNode(self)
var translation = CGPointMake(location.x - previousLocation.x, location.y - previousLocation.y)
crossHair.position = CGPointMake(crossHair.position.x + translation.x * 3, crossHair.position.y + translation.y * 3)
}
}
I have a crosshair on the screen and i can move it using touchesmoved as shown above, but my problem is i don't know how to prevent it from going of the screen. there is the fmaxf & fminf but i am not entirely sure how to use them, any help would be much appreciated.

Answer 1

You can limit the node inside the coordinates using the following code. The following code only checks if the position of the sprite is within the bounds. I assumed the position is at the centre of the sprite.
override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {
for touch: AnyObject in touches {
let location = touch.locationInNode(self)
let previousLocation = touch.previousLocationInNode(self)
var translation = CGPointMake(location.x - previousLocation.x, location.y - previousLocation.y)
var positionX : CGFloat = crossHair.position.x + translation.x * 3
var positionY : CGFloat = crossHair.position.y + translation.y * 3
if positionX < 0 {
positionX = 0
}
else if positionX > self.size.width
{
positionX = self.size.width
}
if positionY < 0 {
positionY = 0
}
else if positionY > self.size.height
{
positionY = self.size.height
}
crossHair.position = CGPointMake(positionX, positionY)
}
}

Answer 2

After getting the position of the crosshair, check whether it is not outside of the screen:
var x = crossHair.position.x;
var y = crossHair.position.y;
if(crossHair.position.x > self.size.width) {
x = self.size.width;
}
if(crossHair.position.x < 0) {
x = 0;
}
if(crossHair.position.y > self.size.height) {
y = self.size.height;
}
if(crossHair.position.y < 0) {
y = 0;
}
crossHair.position = CGPointMake(x,y);