Isn't NSValue an NSObject ? So why am I crashing on
    var coordinatesRawData = NSValue(MKCoordinate: coordinates.first!)
    if coordinatesRawData != nil {
        // Crashing here. I have a valid NSValue object
        aCoder.encodeObject(coordinatesRawData, forKey: "coordinatesRawData")
    }
Error Log
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSKeyedArchiver encodeValueOfObjCType:at:]: this archiver cannot encode structs'
But if I do this
    var coordinatesRawData = NSValue()
    aCoder.encodeObject(coordinatesRawData, forKey: "coordinatesRawData")
There is no crash - Both are NSValues .. right ?
Note, all my other NSCoding / Decoding is working fine.
                        
I didn't even get as far as you did. I crashed on just these two lines:
This tells me that
NSValue(MKCoordinate:)is broken. And it's not a Swift issue; I get the same crash using the same code translated into Objective-C.