For the first error. Is the @objc func fetchCommits() in the class ViewController? if it is then resolving the other errors may make it go away. (sometime xcode is not helpful with errors)

For the "Cannot find 'JSON' in scope". Have you put the SwiftyJSON.swift in the project as public init(parseJSON jsonString: String) of public struct JSON is in that file?

Last error Value of type 'ViewController' has no member 'saveContext'. You should have in the class ViewController this func

func saveContext() {
  if container.viewContext.hasChanges {
    do {
      try container.viewContext.save()
    } catch {
              print("An error occurred while saving: \(error.localizedDescription)")
    }
  }
}