iOS/iPhone Date Time and Date Format (NSDate, Objective-C)

    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"YYYY-MM-dd HH:mm:SS"];
    
    //Optionally for time zone converstions
    [formatter setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Bangkok"]];
    
    NSString *stringFromDate = [formatter stringFromDate:[NSDate date]];
    
    lblDateTime.text = stringFromDate;
    
    [formatter release];

    NSString *currentDateString = @"2012-12-07 08:16:45";
    
    NSDateFormatter *dateFormater = [[NSDateFormatter alloc] init];
    [dateFormater setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Bangkok"]];
    
    [dateFormater setDateFormat:@"YYYY-MM-dd HH:mm:ss"];
    NSDate *currentDate = [dateFormater dateFromString:currentDateString];
    
    NSCalendar* calendar = [NSCalendar currentCalendar];
    NSDateComponents* compoNents = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit
                                    |NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit
                                                fromDate:currentDate];
    
    // Year
    NSMutableString *yy = [NSString stringWithFormat:@"Year =  %d",[compoNents year]];
    lblYear.text = yy;
    
    // Month
    NSMutableString *mm = [NSString stringWithFormat:@"Month =  %d",[compoNents month]];
    lblMonth.text = mm;
    
    // Day
    NSMutableString *dd = [NSString stringWithFormat:@"Day =  %d",[compoNents day]];
    lblDay.text = dd;

//
//  ViewController.h
//  dateTimeApp
//
//  Created by Weerachai on 12/8/55 BE.
//  Copyright (c) 2555 Weerachai. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
{
    
    IBOutlet UILabel *lblDateTime;
    
    IBOutlet UILabel *lblYear;
    
    IBOutlet UILabel *lblMonth;
    
    IBOutlet UILabel *lblDay;
    
    IBOutlet UILabel *lblHour;
    
    IBOutlet UILabel *lblMinute;
    
    IBOutlet UILabel *lblSecond;
}

@end

//
//  ViewController.m
//  dateTimeApp
//
//  Created by Weerachai on 12/8/55 BE.
//  Copyright (c) 2555 Weerachai. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
    
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"YYYY-MM-dd HH:mm:SS"];
    
    //Optionally for time zone converstions
    [formatter setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Bangkok"]];
    
    NSString *stringFromDate = [formatter stringFromDate:[NSDate date]];
    
    lblDateTime.text = stringFromDate;
    
    [formatter release];
    
    
   /*
    // Get date by Current
    NSDate *curentDate = [NSDate date];
    NSCalendar* calendar = [NSCalendar currentCalendar];
    NSDateComponents* compoNents = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit
                                    |NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit
                                               fromDate:curentDate];
    */
     
    // Get date by Sting
    NSString *currentDateString = @"2012-12-07 08:16:45";
    
    NSDateFormatter *dateFormater = [[NSDateFormatter alloc] init];
    [dateFormater setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Bangkok"]];
    
    [dateFormater setDateFormat:@"YYYY-MM-dd HH:mm:ss"];
    NSDate *currentDate = [dateFormater dateFromString:currentDateString];
    
    NSCalendar* calendar = [NSCalendar currentCalendar];
    NSDateComponents* compoNents = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit
                                    |NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit
                                                fromDate:currentDate];
    
    // Year
    NSMutableString *yy = [NSString stringWithFormat:@"Year =  %d",[compoNents year]];
    lblYear.text = yy;
    
    // Month
    NSMutableString *mm = [NSString stringWithFormat:@"Month =  %d",[compoNents month]];
    lblMonth.text = mm;
    
    // Day
    NSMutableString *dd = [NSString stringWithFormat:@"Day =  %d",[compoNents day]];
    lblDay.text = dd;
    
    // Hour
    NSMutableString *h = [NSString stringWithFormat:@"Hour =  %d",[compoNents hour]];
    lblHour.text = h;
    
    // Minute
    NSMutableString *m = [NSString stringWithFormat:@"Minute =  %d",[compoNents minute]];
    lblMinute.text = m;
    
    // Second
    NSMutableString *s = [NSString stringWithFormat:@"Second =  %d",[compoNents second]];
    lblSecond.text = s;
    
    /*
     NSString* input = @"2012-12-07 08:16:45";
     
     NSString* year  = [input substringWithRange: NSMakeRange( 0, 4)];
     NSString* month = [input substringWithRange: NSMakeRange( 5, 2)];
     NSString* day   = [input substringWithRange: NSMakeRange( 8, 2)];
     NSString* time  = [input substringWithRange: NSMakeRange(11, 8)];
     
     NSString* output = [NSString stringWithFormat:@"%@.%@.%@ %@",day,month,year,time]
     */
    
    
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)dealloc {
    [lblDateTime release];
    [lblYear release];
    [lblMonth release];
    [lblDay release];
    [lblHour release];
    [lblMinute release];
    [lblSecond release];
    [super dealloc];
}
@end