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);

在斯威夫特

var dayComponenet = NSDateComponents()
dayComponenet.day = 1

var theCalendar = NSCalendar.currentCalendar()
var nextDate = theCalendar.dateByAddingComponents(dayComponenet, toDate: NSDate(), options: nil)

Swift 4.0(在这个精彩的答案中与Swift 3.0相同，只是为了让像我这样的新手清楚)

let today = Date()
let yesterday = Calendar.current.date(byAdding: .day, value: -1, to: today)

我也有同样的问题;使用NSDate扩展:

- (id)dateByAddingYears:(NSUInteger)years
                 months:(NSUInteger)months
                   days:(NSUInteger)days
                  hours:(NSUInteger)hours
                minutes:(NSUInteger)minutes
                seconds:(NSUInteger)seconds
{
    NSDateComponents * delta = [[[NSDateComponents alloc] init] autorelease];
    NSCalendar * gregorian = [[[NSCalendar alloc]
                               initWithCalendarIdentifier:NSCalendarIdentifierGregorian] autorelease];

    [delta setYear:years];
    [delta setMonth:months];
    [delta setDay:days];
    [delta setHour:hours];
    [delta setMinute:minutes];
    [delta setSecond:seconds];

    return [gregorian dateByAddingComponents:delta toDate:self options:0];
}

NSDate *now = [NSDate date];
int daysToAdd = 1;
NSDate *tomorrowDate = [now dateByAddingTimeInterval:60*60*24*daysToAdd];

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"EEEE, dd MMM yyyy"];
NSLog(@"%@", [dateFormatter stringFromDate:tomorrowDate]);

从iOS 8开始，你可以使用NSCalendar.dateByAddingUnit

Swift 1.x中的示例:

let today = NSDate()
let tomorrow = NSCalendar.currentCalendar()
    .dateByAddingUnit(
         .CalendarUnitDay, 
         value: 1, 
         toDate: today, 
         options: NSCalendarOptions(0)
    )

斯威夫特2.0:

let today = NSDate()
let tomorrow = NSCalendar.currentCalendar()
    .dateByAddingUnit(
        .Day, 
        value: 1, 
        toDate: today, 
        options: []
    )

斯威夫特3.0:

let today = Date()
let tomorrow = Calendar.current.date(byAdding: .day, value: 1, to: today)