Swift-friendly NSCalendar methods

NSCalendar+Swift.swift

// NSCalendar+Swift.swift
// A set of Swift-idiomatic methods for NSCalendar
// Updated for Swift 3.1
//
// (c) 2015 Nate Cook, licensed under the MIT license
// (c) 2017 Tom Kraina, licensed under the MIT license

public extension Calendar {
    /// Returns the hour, minute, second, and nanoseconds of a given date.
    func getTimeFromDate(_ date: Date) -> (hour: Int, minute: Int, second: Int, nanosecond: Int) {
        let components = dateComponents([.hour, .minute, .second, .nanosecond], from: date)
        return (components.hour ?? 0, components.minute ?? 0, components.second ?? 0, components.nanosecond ?? 0)
    }
    
    /// Returns the era, year, month, and day of a given date.
    func getDateItemsFromDate(_ date: Date) -> (era: Int, year: Int, month: Int, day: Int) {
        let components = dateComponents([.era, .year, .month, .day], from: date)
        return (components.era ?? 0, components.year ?? 0, components.month ?? 0, components.day ?? 0)
    }
    
    /// Returns the era, year for week-of-year calculations, week of year, and weekday of a given date.
    func getWeekItemsFromDate(_ date: Date) -> (era: Int, yearForWeekOfYear: Int, weekOfYear: Int, weekday: Int) {
        let components = dateComponents([.era, .yearForWeekOfYear, .weekOfYear, .weekday], from: date)
        return (components.era ?? 0, components.yearForWeekOfYear ?? 0, components.weekOfYear ?? 0, components.weekday ?? 0)
    }
    
    /// Returns the start and length of the next weekend after the given date. Returns nil if the
    /// calendar or locale don't support weekends.
    func nextWeekendAfterDate(_ date: Date) -> (startDate: Date, interval: TimeInterval)? {
        var startDate: Date = .distantFuture
        var interval: TimeInterval = 0
        
        if nextWeekend(startingAfter: date, start: &startDate, interval: &interval, direction: .forward) {
            return (startDate, interval)
        }
        
        return nil
    }
    
    /// Returns the start and length of the weekend before the given date. Returns nil if the
    /// calendar or locale don't support weekends.
    func nextWeekendBeforeDate(_ date: Date) -> (startDate: Date, interval: TimeInterval)? {
        var startDate: Date = .distantPast
        var interval: TimeInterval = 0
        
        if nextWeekend(startingAfter: date, start: &startDate, interval: &interval, direction: .backward) {
            return (startDate, interval)
        }
        
        return nil
    }
    
    /// Returns the start and length of the weekend containing the given date. Returns nil if the
    /// given date isn't in a weekend or if the calendar or locale don't support weekends.
    func rangeOfWeekendContainingDate(_ date: Date) -> (startDate: Date, interval: TimeInterval)? {
        var startDate: Date = .distantPast
        var interval: TimeInterval = 0
        
        if dateIntervalOfWeekend(containing: date, start: &startDate, interval: &interval)
        {
            return (startDate, interval)
        }
        
        return nil
    }
}