ERROR SHOWING in program code ios

Try This to select date from date picker…

-(BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
datePicker =[[UIDatePicker alloc]initWithFrame:CGRectMake(50,150,10, 50)];
datePicker.datePickerMode=UIDatePickerModeDate;
datePicker.hidden=NO;
datePicker.date=[NSDate date];
[datePicker addTarget:self action:@selector(textFieldTitle:) forControlEvents:UIControlEventValueChanged];
[self.view addSubview:datePicker];
UIBarButtonItem * rightBtn=[[UIBarButtonItem alloc]initWithTitle:@"Done" style:UIBarButtonItemStyleDone target:self action:@selector(save:)];
self.navigationItem.rightBarButtonItem=rightBtn;
return true;
}


-(void)textFieldTitle:(id)sender

{
NSDateFormatter *dateFormat=[[NSDateFormatter alloc]init];
dateFormat.dateStyle=NSDateFormatterMediumStyle;
[dateFormat setDateFormat:@"MM/dd/yyyy"];
NSString *str=[NSString stringWithFormat:@"%@",[dateFormat  stringFromDate:datePicker.date]];
self.txtField.text=str;
}

-(void)save:(id)sender
{
self.navigationItem.rightBarButtonItem=nil;
[datePicker removeFromSuperview];

}

To calculate the date….

NSDate *today = [NSDate date];
NSString *birthdate=self.txtField.text;
NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init];
[dateFormatter1 setDateFormat:@"dd-MM-yyyy"];
NSDate *myDate = [[NSDate alloc]init];
myDate=[dateFormatter1 dateFromString:birthdate];


NSDateComponents *ageComponents = [[NSCalendar currentCalendar]
                                   components:NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay
                                   fromDate:myDate
                                   toDate:today
                                   options:0];

NSLog(@"%@",ageComponents);