Why is 0, 0 on CGPoint on the right-center end of the view?

I created a rectangle using CGRect, but I can't seem to center it relative to the frame size. And when setting the x and y values to 0, it would end up in the right-center (not exactly centered, actually, unless it's calculated by the bottom end of the object) end of the screen, rather than the actual center or the left corner. So how would I make point 0, 0 be at the center of the screen, if possible, and how would I center my shape at the (bottom) middle of the screen relative to the frame size?

import PlaygroundSupport
import SpriteKit
class GameScene: SKScene {
var textBackground = SKShapeNode(rect: .zero)
override func didMove(to view: SKView) {
textBackground = SKShapeNode(rect: CGRect(x: 0, y: 0, width: frame.size.width - 300,
height: frame.size.height / 6))
textBackground.fillColor = SKColor.init(red: 255, green: 255, blue: 255, alpha: 0.5)
textBackground.strokeColor = SKColor.clear
addChild(textBackground)
}
@objc static override var supportsSecureCoding: Bool {
get {
return true
}
}
override func update(_ currentTime: TimeInterval) {
}
}
let sceneView = SKView(frame: CGRect(x: 0 , y:0, width: 1024, height: 1366))
if let scene = GameScene(fileNamed: "GameScene") {
// scene.scaleMode = .aspectFill
sceneView.presentScene(scene)
}
PlaygroundSupport.PlaygroundPage.current.liveView = sceneView

Also, my shape width also looks off since I wanted it to cover almost the width of the whole screen except for the ends, so using the frame width and cutting it short a few points was what I thought would be the best way to do it. Only subtracting 300 points was the only way I could get it to work, which looks like a bit too much, so I'm wondering if my view's whole x-coordinates are somehow off?

Any help would be greatly appreciated. Thank you.