Round NSDate to the nearest 5 minutes

Take the minute value, divide by 5 rounding up to get the next highest 5 minute unit, multiply to 5 to get that back into in minutes, and construct a new NSDate.

NSDateComponents *time = [[NSCalendar currentCalendar]
                          components:NSHourCalendarUnit | NSMinuteCalendarUnit
                            fromDate:curDate];
NSInteger minutes = [time minute];
float minuteUnit = ceil((float) minutes / 5.0);
minutes = minuteUnit * 5.0;
[time setMinute: minutes];
curDate = [[NSCalendar currentCalendar] dateFromComponents:time];

The answer from @ipje did the trick for the next 5 minutes but I needed something more flexible and I wanted to get rid of all the magic numbers. I found a solution thanks to an answer to a similar question My solution uses the Swift 5.2 and Measurement to avoid using magic numbers:

extension UnitDuration {
    var upperUnit: Calendar.Component? {
        if self == .nanoseconds {
            return .second
        }

        if self == .seconds {
            return .minute
        }
        if self == .minutes {
            return .hour
        }
        if self == .hours {
            return .day
        }
        return nil
    }
}
extension Date {
    func roundDate(to value: Int, in unit: UnitDuration, using rule: FloatingPointRoundingRule, and calendar: Calendar = Calendar.current) -> Date? {
        guard unit != .picoseconds && unit != .nanoseconds,
            let upperUnit = unit.upperUnit else { return nil }
        let value = Double(value)
        let unitMeasurement = Measurement(value: value, unit: unit)
        let interval = unitMeasurement.converted(to: .seconds).value

        let startOfPeriod = calendar.dateInterval(of: upperUnit, for: self)!.start
        var seconds = self.timeIntervalSince(startOfPeriod)
        seconds = (seconds / interval).rounded(rule) * interval
        return startOfPeriod.addingTimeInterval(seconds)
    }

    func roundDate(toNearest value: Int, in unit: UnitDuration, using calendar: Calendar = Calendar.current) -> Date? {
        return roundDate(to: value, in: unit, using: .toNearestOrEven)
    }

    func roundDate(toNext value: Int, in unit: UnitDuration, using calendar: Calendar = Calendar.current) -> Date? {
        return roundDate(to: value, in: unit, using: .up)
    }
}

In my playground :

let calendar = Calendar.current
let date = Calendar.current.date(from: DateComponents(timeZone: TimeZone.current, year: 2020, month: 6, day: 12, hour: 00, minute: 24, second: 17, nanosecond: 577881))! // 12 Jun 2020 at 00:24

var roundedDate = date.roundDate(toNext: 5, in: .seconds)!
//"12 Jun 2020 at 00:24"
calendar.dateComponents([.nanosecond, .second, .minute, .hour, .day, .month], from: roundedDate) 
// month: 6 day: 12 hour: 0 minute: 24 second: 20 nanosecond: 0 isLeapMonth: false 

roundedDate = date.roundDate(toNearest: 5, in: .seconds)!
// "12 Jun 2020 at 00:24"
calendar.dateComponents([.nanosecond, .second, .minute, .hour, .day, .month], from: roundedDate)
// month: 6 day: 12 hour: 0 minute: 24 second: 15 nanosecond: 0 isLeapMonth: false 

roundedDate = date.roundDate(toNext: 5, in: .minutes)!
// "12 Jun 2020 at 00:25"
calendar.dateComponents([.nanosecond, .second, .minute, .hour, .day, .month], from: roundedDate)
// month: 6 day: 12 hour: 0 minute: 25 second: 0 nanosecond: 0 isLeapMonth: false 

roundedDate = date.roundDate(toNearest: 5, in: .minutes)!
// "12 Jun 2020 at 00:25"
calendar.dateComponents([.nanosecond, .second, .minute, .hour, .day, .month], from: roundedDate)
// month: 6 day: 12 hour: 0 minute: 25 second: 0 nanosecond: 0 isLeapMonth: false 

roundedDate = date.roundDate(toNext: 5, in: .hours)!
// "12 Jun 2020 at 05:00"
calendar.dateComponents([.nanosecond, .second, .minute, .hour, .day, .month], from: roundedDate)
// month: 6 day: 12 hour: 5 minute: 0 second: 0 nanosecond: 0 isLeapMonth: false 

roundedDate = date.roundDate(toNearest: 5, in: .hours)!
// "12 Jun 2020 at 00:00"
calendar.dateComponents([.nanosecond, .second, .minute, .hour, .day, .month], from: roundedDate)
// month: 6 day: 12 hour: 0 minute: 0 second: 0 nanosecond: 0 isLeapMonth: false 

Here's my solution to the original problem (rounding up) using ayianni's wrapper idea.

-(NSDate *)roundDateToCeiling5Minutes:(NSDate *)mydate{
    // Get the nearest 5 minute block
    NSDateComponents *time = [[NSCalendar currentCalendar]
                                           components:NSHourCalendarUnit | NSMinuteCalendarUnit
                                             fromDate:mydate];
    NSInteger minutes = [time minute];
    int remain = minutes % 5;
    // Add the remainder of time to the date to round it up evenly
    mydate = [mydate addTimeInterval:60*(5-remain)];
    return mydate;
}

Had been looking for this myself, but using the example above gave me from year 0001 dates.

Here's my alternative, incorporated with smorgan's more elegant mod suggestion though beware I haven't leak tested this yet:

NSDate *myDate = [NSDate date];
// Get the nearest 5 minute block
NSDateComponents *time = [[NSCalendar currentCalendar] components:NSHourCalendarUnit | NSMinuteCalendarUnit
                                                         fromDate:myDate];
NSInteger minutes = [time minute];
int remain = minutes % 5;
// Add the remainder of time to the date to round it up evenly
myDate = [myDate addTimeInterval:60*(5-remain)];