I know it's a bit long code, but I wanted to make it as readable as possible. This code uses minutesSinceMidnight instead of the localized string.
NSDate *currentDate = [NSDate date];
NSDateComponents *currentDateComponents = [calendar components:NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit fromDate:currentDate];
NSDateComponents *currentDateToMidnight = [[NSDateComponents alloc] init];
[currentDateToMidnight setHour:-[currentDateComponents hour]];
[currentDateToMidnight setMinute:-[currentDateComponents minute]];
[currentDateToMidnight setSecond:-[currentDateComponents second]];
NSDate *midnight = [calendar dateByAddingComponents:currentDateToMidnight toDate:currentDate options:0];
NSDateComponents *midnightToDesiredDate = [[NSDateComponents alloc] init];
[midnightToDesiredDate setMinute:minutesSinceMidnight];
NSDate *desiredDate = [calendar dateByAddingComponents:midnightToDesiredDate toDate:midnight options:0];