iphone SDK: How to implement a modal date picker?

Question

How can I implement a modal date picker?

What I want to happen is when the user enters a text field, a new view is created that has the date picker on it. From there, t

Answer 1

Use a delegate!

Header:

@class DatePickerController;
@protocol DatePickerControllerDelegate
- (void) datePickerController:(DatePickerController *)controller didPickDate:(NSDate *)date;
@end

@interface DatePickerController : UIViewController {
  UIDatePicker *datePicker;
  NSObject  *delegate;
}

@property (nonatomic, retain) UIDatePicker *datePicker;
@property (nonatomic, assign) NSObject  *delegate;
@end

class:

@implementation DatePickerController
- (void) loadView {
  self.view = [[[UIView alloc] init] autorelease];
  self.datePicker = [[[UIDatePicker alloc] init] autorelease];
  [self.view addSubview:self.datePicker];
  UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
  [button setTitle:@"Done" forState:UIControlStateNormal];
  button.center = CGPointMake(160,240);
  [button addTarget:self action:@selector(done) forControlEvents:(UIControlEventTouchUpInside)];
  [self.view addSubview:button];
}

- (void) done {
  [delegate datePickerController:self didPickDate:datePicker.date];
}

- (void) dealloc {
  [datePicker release];
  [super dealloc];
}

@end

All that crap in loadView can be replaced with a NIB if you prefer. Just make sure to declare datePicker as an IBOutlet. And when you want to actually use it:

- (void) pickDate {
  DatePickerController *screen = [[[DatePickerController alloc] init] autorelease];
  screen.delegate = self;
  [self presentModalViewController:screen animated:YES];
}

- (void) datePickerController:(DatePickerController *)controller didPickDate:(NSDate *)date {
  [self doSomethingWithDate:date];
  [controller dismissModalViewControllerAnimated:YES];
}