Swift 3: Internal Extension to Set Time - swift3

Question

I had this internal Date extension that appears to no longer work in Swift 3:
internal extension DateComponents {
func to12pm() {
self.hour = 12
self.minute = 0
self.second = 0
}
}
The error message is:
Cannot assign to property: 'self' is immutable
How do I achieve this in Swift 3?
Additional Info (if needed): It was called by this Date extension:
func endOfWeek(_ weekday: Int) -> Date? {
guard
let cal = Calendar.current,
var comp: DateComponents = (cal as Calendar).components([.weekOfYear], from: self)
else {
return nil
}
comp.weekOfYear = 1
comp.day -= 1
comp.to12pm()
return (cal as NSCalendar).date(byAdding: comp, to: self.startOfWeek(weekday)!, options: [])!
}
Which now looks like this in Swift 3:
func endOfWeek(_ weekday: Int) -> Date? {
let cal = Calendar.current
var comp = cal.dateComponents([.weekOfYear], from: self)
comp.weekOfYear = 1
comp.day? -= 1
//This does not have the "comp.to12pm()" that the Swift 2 version did
return cal.date(byAdding: comp, to: self.startOfWeek(weekday)!)!
}

Answer 1

DateComponents is now a struct thats why it is throwing that error:
Cannot assign to property: 'self' is immutable
You need to create a new var from self, change it and return it as follow:
extension DateComponents {
var to12pm: DateComponents {
var components = self
components.hour = 12
components.minute = 0
components.second = 0
components.nanosecond = 0
return components
}
}