NSCoder: Unrecognized selector sent to instance

Question

So, I\'m new to iOS and have been using online tutorials to learn the platform. The tutorials I\'m using are building apps with iOS 9 while I\'m using iOS 10. Because of that I

Answer 1

With the help of a couple of users and some added searching, I was able to figure out the cause of my problem.

Per the suggestion of the previously mentioned users, I added the NSCoding protocol to my CalendarEvent class.

class CalendarEvent : NSObject, NSCoding {
    ....
}

Unfortunately, that didn't completely fix the issue, but it was a start. A few errors and a quick search showed me that I had to change this:

init(withCoder coder : NSCoder){
    ....
}
func encodeWithCoder(coder : NSCoder){
    ....
}

to this:

required init(coder : NSCoder) {
    ....
}
func encode(with aCoder : NSCoder) {
    ....
}

After making those changes, my code ran perfectly fine.