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Auto-scroll to the current/next session in Programme #2

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Auto-scroll to the current/next session in Programme #2

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Auto-scroll to the current/next session in Programme
marcpalmer Sep 5, 2018
2b05d64
Code review updates
marcpalmer Sep 6, 2018
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36 changes: 36 additions & 0 deletions iOSDevUK/Controllers/Sessions/ProgrammeTableViewController.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@ class ProgrammeTableViewController: UIViewController, UITableViewDelegate, UITab

var selectedSessionItem: SessionItem?

var shouldScrollToCurrent: Bool = true

// MARK: - Lifecycle

override func viewDidLoad() {
Expand All @@ -43,6 +45,16 @@ class ProgrammeTableViewController: UIViewController, UITableViewDelegate, UITab
super.didReceiveMemoryWarning()
}

override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)

if shouldScrollToCurrent {
// We'd rather not animate, but how can we know when the table view knows the correct
// size for all the cells in order to scroll to the right place, before the view appears?
scrollToCurrentSession(animated: true)
}
}

// MARK: - Data Initialisation

func accessDayList(withContext context: NSManagedObjectContext) -> [Day] {
Expand Down Expand Up @@ -86,6 +98,30 @@ class ProgrammeTableViewController: UIViewController, UITableViewDelegate, UITab
}
}

/// Find the current or next session for the current set of sessions and scroll to it.
func scrollToCurrentSession(animated: Bool) {
guard let fetchedResultsController = fetchedResultsController else {
return
}

/// Find the session in the already-fetched results
let nextOrCurrentSession = fetchedResultsController.fetchedObjects?.first { session in
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@JoachimK JoachimK Sep 6, 2018

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I just noticed that the Session object already has a way to calculate the current and the next Session. Maybe you can use Session.nowSession(forDate:) and Session.nextSession(forDate:) here instead of reimplementing it?

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@marcpalmer marcpalmer Sep 7, 2018

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I saw those too, but it seems like a silly idea to run 2 Core Data queries to find this?

guard let endTime = session.endTime else {
return false
}
return endTime.timeIntervalSinceNow > 0
}

/// If we found one, resolve it to a section index and row
if let sessionToScrollTo = nextOrCurrentSession {
if let indexPathOfSessionToScrollTo = fetchedResultsController.indexPath(forObject: sessionToScrollTo) {
tableView.scrollToRow(at: indexPathOfSessionToScrollTo, at: .top, animated: animated)
}
}

shouldScrollToCurrent = false
}

// MARK: - Segmented Control

func setupSegmentedControlWithDays(_ days: [Day]) {
Expand Down