I could not find a good signature capturer iOS made in Swift, so I gave it a try. I leaned heavily on the blog entry Capture a Signature on iOS by Jason Harwig, and Macheads101, he has a great tutorial on YouTube.
Add a new view where you want the signature capture field. Set its class to YPDrawSignatureView, and connect it to an IBOutlet property in your UIViewController (or whatever else).
Add YPDrawSignature.swift to your project
Geert-Jan Nilsen ( gert@yuppielabel.com ) Yuppielabel
YPDrawSignatureView is available under the MIT license. See the LICENSE file for more info.