[SOLVED] How would I go about getting the lowest and highest coordinate numbers from touchpoints?

How would I go about getting the lowest and highest coordinate numbers from touchpoints?

I'm wanting to get the lowest and highest x and y coordinates from the touchesmoved event no matter what the shape being drawn is. Basically I want to create a cgrect that encompasses the shape. I have no idea how to go about this.

Solution

There are various ways to do this.

UIBezierPath has a bounds method that will give you a bounding rectangle that contains all the points in the path. If you are building your shape into a UIBezierPath that should be all you need.

If you need to track the bounds yourself, set up some variables and adjust them as needed:

var minY = CGFloat.greatestFiniteMagnitude
var maxY = -CGFloat.greatestFiniteMagnitude

var minX = CGFloat.greatestFiniteMagnitude
var maxX = -CGFloat.greatestFiniteMagnitude

As you collect points from your user, if the x coordinate is < minX, update minX. If it's > maxX, update maxX. Do the same for minY and maxY.

Once you have maximum and minimum values for x and y it's trivial to convert those values to a bounding rectangle. Some sample code:

extension CGRect {
    init(minX: CGFloat,
         minY: CGFloat,
         maxX: CGFloat,
         maxY: CGFloat) {
        self.init()
       origin = CGPoint(x: minX, y: minY)
       size = CGSize(width: maxX - minX, height: maxY - minY)
   }
}


let aMinX: CGFloat = CGFloat(Int.random(in: 0...50))
let aMinY: CGFloat = CGFloat(Int.random(in: 0...50))
let aMaxX: CGFloat = CGFloat(Int.random(in: 60...200))
let aMaxY: CGFloat = CGFloat(Int.random(in: 60...200))
let aRect: CGRect = CGRect(minX: aMinX,
                           minY: aMinY,
                           maxX: aMaxX,
                           maxY: aMaxY)
print(aRect)