Read more here: https://www.hackingwithswift.com/articles/178/super-powered-string-interpolation-in-swift-5-0

Padding in String Interpolation.swift

let hello = "Hello"
let world = "World!"
print("\(hello, padLeft: 10) \(world, padLeft: 10)") // Spaces are the default padding
print("\(hello, padLeft: 10, with: "H") \(world, padLeft: 10, with: "W")")

extension String.StringInterpolation {
	mutating func appendInterpolation(
		_ str: String,
		padLeft length: Int,
		with padding: String = " "
	) {
		let paddingCount = length - str.count
		if 0 < paddingCount {
			appendLiteral(String(repeating: padding, count: paddingCount))
		}
		
		appendLiteral(str)
	}
}