UIDatePicker issue with NSdate - ios

Question

i have an NSDate object from an old date which i am getting from my DB. Now i need to set my UIDatePicker date to current date but with hour and minute value from my stored NSDate object which i have got from my DB.
So how to extract hour and minute from old date and set it to current UIDatePicker NSdate.
Thanks

Answer 1

Since a NSDate can't be changed after it's initialization, you have to recreate it:
To get the hour and minute component of the NSDate use NSCalendar:
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *dateComponents = [gregorian components:(NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit) fromDate:yourOriginalDateHere];
NSInteger hour = [dateComponents hour];
NSInteger minute = [dateComponents minute];
NSInteger second = [dateComponents second];
Then you can create a new NSDate (also using NSCalendar):
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *dateComponents = [gregorian components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:[NSDate date]]; //[NSDate date] is the current date
[dateComponents setHour:hour];
[dateComponents setMinute:minute];
[dateComponents setSecond:second];
NSDate *newDate = [gregorian dateFromComponents:dateComponents];

Answer 2

NSCalendar *cal = [NSCalendar autoupdatingCurrentCalendar];
NSDateComponents *dbDateComps = [cal components:(kCFCalendarUnitHour | kCFCalendarUnitMinute) fromDate:YOUR_DATE_FRM_DB];
NSDateComponents *currentComps = [cal components:(kCFCalendarUnitYear | kCFCalendarUnitMonth | kCFCalendarUnitDay) fromDate:[NSDate date]];
[currentComps setHour:[dbDateComps hour]];
[currentComps setMinute:[dbDateComps minute]];
NSDate *resultDate = [currentComps date];