Swift: too many static functions? - swift

Question

I have a class that represents Calendar items (model) retrieved from the event store. I haven't implemented any delegation yet for the AppDelegate or ViewControllers.
All my methods in this class are static functions - the main reason is so that I can "see" them from the AppDelegate or the VC. I have a suspicion that:
1) I need to make this a singleton - whose only function is to retrieve calendar items from the eventStore and post to the UI
2) learn how to code better - perhaps creating an instance of the class in the AppDelegate and the VC
This is still very fuzzy to me - not sure if posting code would help, but the class has a bunch of "static func .... doSomething() { ...}" and is called by the AppDelegate and VC as "ClassName.doSomething()..."
I'm prepared to refactor the Class code, thinking that a singleton would work - or perhaps things are just fine as they are...
EDITED: Adding code:
import Foundation
import EventKit
class Calendars: NSObject {
enum calendarAuthState {
case restricted
case authorized
case denied
case notDetermined
}
struct Calendar {
var id: String
var color: NSColor
var title: String
var isUserActive: Bool
var events: [EventItem]
}
struct EventItem {
var originalStartDate: Date
var date: String
var title: String
var isAllDayEvent: Bool
}
static var calendarState: calendarAuthState = .notDetermined
static var eventStore = EKEventStore()
static var currentCalendars = [Calendar]()
//MARK: Check Calendar Authorization Status
static func calendarAuthorizationStatus() {
let status = EKEventStore.authorizationStatus(for: .event)
switch (status) {
case EKAuthorizationStatus.notDetermined:
// This happens on first-run
calendarState = .notDetermined
case EKAuthorizationStatus.authorized:
calendarState = .authorized
case EKAuthorizationStatus.restricted:
self.requestAccessToCalendar()
calendarState = .restricted
case EKAuthorizationStatus.denied:
self.requestAccessToCalendar()
calendarState = .denied
}
}
static func requestAccessToCalendar() {
self.eventStore.requestAccess(to: EKEntityType.event, completion: {
(accessGranted: Bool, error: Error?) in
if accessGranted == true {
DispatchQueue.main.async(execute: {
self.calendarState = .authorized
})
} else {
DispatchQueue.main.async(execute: {
self.calendarState = .denied
})
}
})
}
//MARK: Do the two below
static func createMenuFromCalendars() {
guard calendarState == .authorized else {
return
}
let calendars = self.returnCalendars()
guard calendars.count >= 0 else {
return
}
self.addCalendarsToMenuItems(from: calendars)
}
//MARK: First, return the calendar titles from the Store
static func returnCalendars() -> [Calendar] {
guard self.calendarState == .authorized else {
return[]
}
let calendars = self.eventStore.calendars(for: .event)
for calendar in calendars {
self.currentCalendars.append(Calendar(id: calendar.calendarIdentifier, color: calendar.color, title: calendar.title, isUserActive: false, events: []))
}
return self.currentCalendars
}
//MARK: Next, send those to the Menu for MenuItem creation
static func addCalendarsToMenuItems(from calendars:[Calendar]) {
let appDelegate = NSApplication.shared.delegate as! AppDelegate
let appMainMenu = NSApp.mainMenu
if let calendarMenu = appMainMenu?.item(withTitle: "Calendars") {
let calendarSubMenu = calendarMenu.submenu
for calendar in calendars {
let menuItem = calendarSubMenu?.addItem(withTitle: calendar.title, action: #selector(appDelegate.actionFromSelectedCalendar) , keyEquivalent: "")
menuItem?.isEnabled = true
menuItem?.state = .off
menuItem?.target = appDelegate.self
menuItem?.toolTip = calendar.id
}
}
}
class func retrieveCalendarEvents() {
guard self.calendarState == .authorized || !(self.currentCalendars.isEmpty) else {
return
}
let startDate = Date()
let endDate = Date(timeIntervalSinceNow: 4*24*3600)
var activeCalendars = findUserActiveCalendars(in: currentCalendars)
//need to flush the events at this stage or they'll pile
guard !((activeCalendars?.isEmpty)!) else {
return
}
var eventCalendar = [EKCalendar]()
for dayBookCalendar in activeCalendars! {
// much of the risk here is unwrapping optionals unsafely!!!!! - refactor this and other please
eventCalendar.append(self.eventStore.calendar(withIdentifier: dayBookCalendar.id)!)
let eventPredicate = eventStore.predicateForEvents(withStart: startDate, end: endDate, calendars: eventCalendar)
let returnedEvents = eventStore.events(matching: eventPredicate)
let calendarIndex = findCalendarIndex(by: dayBookCalendar.id, in: currentCalendars)
for event in returnedEvents {
let eventItems = eventItem(from: event)
currentCalendars[calendarIndex!].events.append(eventItems)
}
}
}
//MARK: Helper methods and stuff
static func changeUserCalendarState(with id:String, state:Bool) {
guard !(currentCalendars.isEmpty) else {
return
}
let calendarIndex = findCalendarIndex(by: id, in:self.currentCalendars)
if let calendarIndex = calendarIndex {
currentCalendars[calendarIndex].isUserActive = !state
retrieveCalendarEvents()
}
}
static func findCalendarIndex(by id:String, in calendarArray: [Calendar]) -> Int? {
return calendarArray.index(where: {$0.id == id})
}
static func findUserActiveCalendars(in calendarArray: [Calendar]) -> [Calendar]? {
return calendarArray.filter({$0.isUserActive == true})
}
// static func flushEventsFromCalendar(in calendarArray: inout [Calendar]) {
// calendarArray.map({$0.events.removeAll()})
// }
static func eventItem(from events:EKEvent) -> EventItem {
return EventItem(originalStartDate: events.startDate, date:eventTime(from: events.startDate), title: events.title!, isAllDayEvent: events.isAllDay)
}
static func parseCalendarEvents(from events:[EKEvent]) -> [EventItem] { //can this be variadic?
var calendarEvents = [EventItem]()
for event in events {
calendarEvents.append(eventItem(from: event))
}
return calendarEvents
}
static func eventTime(from date:Date) -> String {
let dateFormatter = DateFormatter()
dateFormatter.timeStyle = .short
dateFormatter.locale = Locale.current
let stringTime = dateFormatter.string(from: date)
return stringTime
}
}
''

Answer 1

I think you're making an elementary mistake about object-oriented programming. In your Calendars class you seem to have encapsulated all the code for accessing the user's calendar. Then you seem to have reasoned: "Well, this code needs to be callable from anywhere. Therefore all my class's members need to be global (static / class)."
That's a mistake. There is nothing wrong with doing such encapsulation; indeed it's a good thing. But then the way to use your encapsulation is with a helper instance. For example, let's say you're in a view controller (which is most likely after all). Then it can have a property:
let calendarHelper = Calendars()
Now all (or nearly all) your members can (and should) become instance members. Remember, instances of the same type each get to maintain state separately from one another; that is part of their encapsulation. You're going to want that ability.
If your underlying reason for thinking you need static/class members is that you only want one EKEventStore instance for the life of the app, then push the globalness / staticness down to that one object (e.g. by a "shared" EKEventStore and methods for accessing it) and let everything else be a normal instance member.

Answer 2

From what you've said, suspicion 1) is correct - you need to use a singleton:
class CalendarService {
private var eventStore = EKEventStore()
//Static shared instance, this is your singleton
static var sharedInstance = CalendarService()
//Your public methods for adding events can go here
public func doSomething() {
//...
}
//As can your private methods for producing, deleting and editing calendar events + checking permissions
}
Usage:
CalendarService.sharedInstance.doSomething()
I can't really say much more without specific examples of your existing code.