在swift中，您可以在NSDate中添加扩展方法

extension NSDate {
    func addNoOfDays(noOfDays:Int) -> NSDate! {
        let cal:NSCalendar = NSCalendar.currentCalendar()
        cal.timeZone = NSTimeZone(abbreviation: "UTC")!
        let comps:NSDateComponents = NSDateComponents()
        comps.day = noOfDays
        return cal.dateByAddingComponents(comps, toDate: self, options: nil)
    }
}

你可以用这个

NSDate().addNoOfDays(3)

斯威夫特2.0

let today = NSDate()    
let calendar = NSCalendar.currentCalendar()
let tomorrow = calendar.dateByAddingUnit(.Day, value: 1, toDate: today, options: NSCalendarOptions.MatchFirst)

你可以使用NSDate的方法- (id)dateByAddingTimeInterval:(NSTimeInterval)秒，其中秒为60 * 60 * 24 = 86400

NSDate *now = [NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit fromDate:now];
NSDate *startDate = [calendar dateFromComponents:components];
NSLog(@"StartDate = %@", startDate);

components.day += 1;
NSDate *endDate = [calendar dateFromComponents:components];
NSLog(@"EndDate = %@", endDate);

这是一个通用的方法，它允许您在指定的日期中添加/减去任何类型的单位(年/月/日/小时/秒等)。

使用Swift 2.2

func addUnitToDate(unitType: NSCalendarUnit, number: Int, date:NSDate) -> NSDate {

    return NSCalendar.currentCalendar().dateByAddingUnit(
        unitType,
        value: number,
        toDate: date,
        options: NSCalendarOptions(rawValue: 0))!

}

print( addUnitToDate(.Day, number: 1, date: NSDate()) ) // Adds 1 Day To Current Date
print( addUnitToDate(.Hour, number: 1, date: NSDate()) ) // Adds 1 Hour To Current Date
print( addUnitToDate(.Minute, number: 1, date: NSDate()) ) // Adds 1 Minute To Current Date

// NOTE: You can use negative values to get backward values too

NSDate *today=[NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier: NSGregorianCalendar];
NSDateComponents *components=[[NSDateComponents alloc] init];
components.day=1;
NSDate *targetDate =[calendar dateByAddingComponents:components toDate:today options: 0];