This is a simple drawing view made with SwiftUI

DrawingView.swift

import Foundation
import SwiftUI

struct SignatureLine {
    var points = [CGPoint]()
    let width = 3.0
}

struct DrawingView: View {
    @State private var lines = [SignatureLine]()
    @State private var currentLine: SignatureLine?
        
    var body: some View {
        Canvas { context, size in
            for line in lines {
                var path = Path()
                path.addLines(line.points)
                context.stroke(path, with: .color(.primary), lineWidth: line.width)
            }
        }
        .gesture(dragGesture)
    }
    
    private var dragGesture: some Gesture {
        DragGesture(minimumDistance: 0)
            .onChanged(updateLines)
            .onEnded { _ in
                currentLine = nil
            }
    }
    
    private func updateLines(dragValue: DragGesture.Value) {
        if currentLine == nil {
            currentLine = SignatureLine()
            lines.append(currentLine!)
        }
        currentLine!.points.append(dragValue.location)
        guard lines.count > 0 else { return }
        lines[lines.count - 1].points = currentLine!.points
    }
}