List of all American holidays as NSDates

If you only want US federal Holidays, I wrote this method. You could use these techniques to calculate any holiday though.

-(NSArray *)getUSHolidyas{
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    formatter.dateFormat = @"yyyy";

    NSString *year = [formatter stringFromDate:[NSDate date]];
    formatter.dateFormat = @"M/d/yyyy";

    //Constant Holidays
    NSDate *newYearsDay = [formatter dateFromString:[NSString stringWithFormat:@"1/1/%@",year]]; //Use next year for the case where we are adding days near end of december.
    NSDate *indDay = [formatter dateFromString:[NSString stringWithFormat:@"7/4/%@",year]];
    NSDate *vetDay = [formatter dateFromString:[NSString stringWithFormat:@"11/11/%@",year]];
    NSDate *xmasDay = [formatter dateFromString:[NSString stringWithFormat:@"12/25/%@",year]];


    //Variable Holidays
    NSInteger currentYearInt = [[[NSCalendar currentCalendar]
                                 components:NSYearCalendarUnit fromDate:[NSDate date]] year];

    NSDate *mlkDay = [self getTheNth:3 occurrenceOfDay:2 inMonth:1 forYear:currentYearInt];
    NSDate *presDay = [self getTheNth:3 occurrenceOfDay:2 inMonth:2 forYear:currentYearInt];
    NSDate *memDay = [self getTheNth:5 occurrenceOfDay:2 inMonth:5 forYear:currentYearInt]; // Let's see if there are 5 Mondays in May
    NSInteger month = [[[NSCalendar currentCalendar] components:NSYearCalendarUnit fromDate:memDay] month];
    if (month > 5) { //Check that we are still in May
        memDay = [self getTheNth:4 occurrenceOfDay:2 inMonth:5 forYear:currentYearInt];
    }
    NSDate *labDay = [self getTheNth:1 occurrenceOfDay:2 inMonth:9 forYear:currentYearInt];
    NSDate *colDay = [self getTheNth:2 occurrenceOfDay:2 inMonth:10 forYear:currentYearInt];
    NSDate *thanksDay = [self getTheNth:4 occurrenceOfDay:5 inMonth:11 forYear:currentYearInt];

    return @[newYearsDay,mlkDay,presDay,memDay,indDay,labDay,colDay,vetDay,thanksDay,xmasDay];
}

-(NSDate *)getTheNth:(NSInteger)n occurrenceOfDay:(NSInteger)day inMonth:(NSInteger)month forYear:(NSInteger)year{

    NSDateComponents *dateComponents = [[NSDateComponents alloc] init];

    dateComponents.year = year;
    dateComponents.month = month;
    dateComponents.weekday = day; // sunday is 1, monday is 2, ...
    dateComponents.weekdayOrdinal = n; // this means, the first of whatever weekday you specified
    return [[NSCalendar currentCalendar] dateFromComponents:dateComponents];
}

• Here you'll find RSS-feeds with the holidays. It doesn't list year, but in the docs you'll find information how to change date ranges.
• Download it. I would suggest ASIHTTPRequest for that task.
  parse the RSS-feed. you can do so by normal XML-parsing, or you use a specialized parser. MWFeedParser would be one option.
• Save the dates. either by using CoreData, or Event Kit Framework

Swift 4: Check this link for getting the US Holiday Dates for easter and memorial day. Using NSDate to get date for Easter

I edited the above link code add some more Holidays:

extension Date {
var isUSHoliday: Bool {
    let components = Calendar.current.dateComponents([.year, .month, .day, .weekday, .weekdayOrdinal], from: self)
    guard let year = components.year,
        let month = components.month,
        let day = components.day,
        let weekday = components.weekday,
        let weekdayOrdinal = components.weekdayOrdinal else { return false }
    
    let easterDateComponents = Date.dateComponentsForEaster(year: year)
    let easterMonth: Int = easterDateComponents?.month ?? -1
    let easterDay: Int = easterDateComponents?.day ?? -1
    let memorialDay = Date.dateComponentsForMemorialDay(year: year)?.day ?? -1
    
    // weekday is Sunday==1 ... Saturday==7
    // weekdayOrdinal is nth instance of weekday in month
    
    switch (month, day, weekday, weekdayOrdinal) {
    case (1, 1, _, _): return true                      // Happy New Years
    case (1, _, 2, 3): return true                      // Martin Luther King - 3rd Mon in Jan
    case (2, 14, _, _): return true                     // Valentine day - 14th in Feb
    case (2, _, 2, 3): return true                      // Washington's Birthday - 3rd Mon in Feb
    case (3, 17, _, _): return true                     // Saint Patrick's Day - 17th Mar
    case (easterMonth, easterDay, _, _): return true    // Easter - rocket science calculation
    case (5, _, 1, 2): return true                      // Mothers day - 2nd Sun in May
    case (5, memorialDay, _, _): return true            // Memorial Day
    case (5, _, 1, 3): return true                      // Fathers day - 3rd Sun in May
    case (7, 4, _, _): return true                      // Independence Day - 4th July
    case (9, _, 2, 1): return true                      // Labor Day - 1st Mon in Sept
    case (10, _, 2, 2): return true                     // Columbus Day - 2nd Mon in Oct
    case (10, 31, _, _): return true                    // Halloween Day - 31st Oct
    case (11, 11, _, _): return true                    // Veterans Day  - 11th Nov
    case (11, _, 5, 4): return true                     // Happy Thanksgiving - 4th Thurs in Nov
    case (12, 25, _, _): return true                    // Christmas/Happy Holiday
    case (12, 31, _, _): return true                    // New years Eve
    default: return false
    }
    
}
//New Year
static func newYearDay(year: Int) -> Date? {
    var firstDayJan = DateComponents()
    firstDayJan.month = 1 // 1st Month
    firstDayJan.day  = 1  // 1st Day
    firstDayJan.year = year
    return Calendar.current.date(from: firstDayJan)
}
// Martin Luther King Jr Day
static func martinLKDay(year: Int) -> Date? {
    var thirdMonJan = DateComponents()
    thirdMonJan.month = 1 //1 month
    thirdMonJan.weekday  = 2 // Monday
    thirdMonJan.weekdayOrdinal = 3 //3rd week
    thirdMonJan.year = year
    return Calendar.current.date(from: thirdMonJan)
}
//Valentine Day
static func valentineDay(year: Int) -> Date? {
    var firstDayFeb = DateComponents()
    firstDayFeb.month = 2
    firstDayFeb.day  = 14
    firstDayFeb.year = year
    return Calendar.current.date(from: firstDayFeb)
}
//Washington's Birthday
static func washingtonBDay(year: Int) -> Date? {
    var thirdMonFeb = DateComponents()
    thirdMonFeb.month = 2 //month Feb
    thirdMonFeb.weekday  = 2 // Monday
    thirdMonFeb.weekdayOrdinal = 3 //3rd week
    thirdMonFeb.year = year
    return Calendar.current.date(from: thirdMonFeb)
}
//Saint Patrick's Day
static func stPatrickDay(year: Int) -> Date? {
    var seventeenthMar = DateComponents()
    seventeenthMar.month = 3
    seventeenthMar.day  = 17
    seventeenthMar.year = year
    return Calendar.current.date(from: seventeenthMar)
}
//Easter
static func easterHoliday(year: Int) -> Date? {
    guard let dateComponents = Date.dateComponentsForEaster(year: year) else { return nil }
    return Calendar.current.date(from: dateComponents)
}

static func dateComponentsForEaster(year: Int) -> DateComponents? {
    // Easter calculation from Anonymous Gregorian algorithm
    // AKA Meeus/Jones/Butcher algorithm
    let a = year % 19
    let b = Int(floor(Double(year) / 100))
    let c = year % 100
    let d = Int(floor(Double(b) / 4))
    let e = b % 4
    let f = Int(floor(Double(b+8) / 25))
    let g = Int(floor(Double(b-f+1) / 3))
    let h = (19*a + b - d - g + 15) % 30
    let i = Int(floor(Double(c) / 4))
    let k = c % 4
    let L = (32 + 2*e + 2*i - h - k) % 7
    let m = Int(floor(Double(a + 11*h + 22*L) / 451))
    var dateComponents = DateComponents()
    dateComponents.month = Int(floor(Double(h + L - 7*m + 114) / 31))
    dateComponents.day = ((h + L - 7*m + 114) % 31) + 1
    dateComponents.year = year
    guard let easter = Calendar.current.date(from: dateComponents) else { return nil } // Convert to calculate weekday, weekdayOrdinal
    return Calendar.current.dateComponents([.year, .month, .day, .weekday, .weekdayOrdinal], from: easter)
}
//Mother's Days
static func mothersDay(year: Int) -> Date? {
    var secondSunMay = DateComponents()
    secondSunMay.month = 5
    secondSunMay.weekday = 1
    secondSunMay.weekdayOrdinal = 2
    secondSunMay.year = year
    return Calendar.current.date(from: secondSunMay)
}

//Memorial Day
static func dateComponentsForMemorialDay(year: Int) -> DateComponents? {
    guard let memorialDay = Date.memorialDay(year: year) else { return nil }
    return NSCalendar.current.dateComponents([.year, .month, .day, .weekday, .weekdayOrdinal], from: memorialDay)
}
static func memorialDay(year: Int) -> Date? {
    let calendar = Calendar.current
    var firstMondayJune = DateComponents()
    firstMondayJune.month = 6
    firstMondayJune.weekdayOrdinal = 1  // 1st in month
    firstMondayJune.weekday = 2 // Monday
    firstMondayJune.year = year
    guard let refDate = calendar.date(from: firstMondayJune) else { return nil }
    var timeMachine = DateComponents()
    timeMachine.weekOfMonth = -1
    return calendar.date(byAdding: timeMachine, to: refDate)
}
//Fathers Day
static func fathersDay(year: Int) -> Date? {
    var thirdSunJun = DateComponents()
    thirdSunJun.month = 6
    thirdSunJun.weekday = 1
    thirdSunJun.weekdayOrdinal = 3
    thirdSunJun.year = year
    return Calendar.current.date(from: thirdSunJun)
}

//Independence Day
static func independenceDay(year: Int) -> Date? {
    var fourthJuly = DateComponents()
    fourthJuly.month = 7
    fourthJuly.day = 4
    fourthJuly.year = year
    return Calendar.current.date(from: fourthJuly)
}
//Labor Day
static func laborDay(year: Int) -> Date? {
    var firstSunSep = DateComponents()
    firstSunSep.month = 9
    firstSunSep.weekday = 2
    firstSunSep.weekdayOrdinal = 1
    firstSunSep.year = year
    return Calendar.current.date(from: firstSunSep)
}
//Columbus Day
static func columbusDay(year: Int) -> Date? {
    var firstSunSep = DateComponents()
    firstSunSep.month = 10
    firstSunSep.weekday = 2
    firstSunSep.weekdayOrdinal = 2
    firstSunSep.year = year
    return Calendar.current.date(from: firstSunSep)
}
//Halloween
static func halloweenDay(year: Int) -> Date? {
    var thirtyFirstOct = DateComponents()
    thirtyFirstOct.month = 10
    thirtyFirstOct.day = 31
    thirtyFirstOct.year = year
    return Calendar.current.date(from: thirtyFirstOct)
}

//Veterans
static func veteransDay(year: Int) -> Date? {
    var eleventhNov = DateComponents()
    eleventhNov.month = 11
    eleventhNov.day = 11
    eleventhNov.year = year
    return Calendar.current.date(from: eleventhNov)
}
//Thanks Giving Day
static func thanksGivingDay(year: Int) -> Date? {
    var fourthThuNov = DateComponents()
    fourthThuNov.month = 11
    fourthThuNov.weekday = 5
    fourthThuNov.weekdayOrdinal = 4
    fourthThuNov.year = year
    return Calendar.current.date(from: fourthThuNov)
}
//Christmas
static func christmasDay(year: Int) -> Date? {
    var christmasDay = DateComponents()
    christmasDay.month = 12
    christmasDay.day = 25
    christmasDay.year = year
    return Calendar.current.date(from: christmasDay)
}

//New Year Eve
static func newYearEve(year: Int) -> Date? {
    var thirtyFirstDec = DateComponents()
    thirtyFirstDec.month = 12
    thirtyFirstDec.day = 31
    thirtyFirstDec.year = year
    return Calendar.current.date(from: thirtyFirstDec)
}


static func getHolidayArray(year: Int) -> [Date?] {
    return [newYearEve(year:year),Date.martinLKDay(year: year),Date.valentineDay(year: year),Date.washingtonBDay(year: year),Date.stPatrickDay(year: year),Date.easterHoliday(year: year),Date.mothersDay(year: year),Date.memorialDay(year: year),Date.fathersDay(year: year),Date.independenceDay(year: year),Date.laborDay(year: year),Date.columbusDay(year: year),Date.halloweenDay(year: year),Date.veteransDay(year: year),Date.thanksGivingDay(year: year),Date.christmasDay(year: year),Date.newYearEve(year: year)]
}
}

Get date:

let date = Date.easterHoliday(year: 2019)

For holiday array:

let holidayArr = Date.getHolidayArray(year: 2019)