iPhone SDK : How to implement a modal date picker?

Question

如何实现模态日期选择器？

我想要发生的是，当用户输入文本字段时，会创建一个带有日期选择器的新 View 。从那里，用户可以进行交互并选择日期。当 View 关闭时，它应该以某种方式将日期返回给调用者。这可能吗？

顺便说一句，由于空间原因，我无法将日期选择器放在主窗体上。

提前致谢。

Answer 1

使用委托(delegate)!

标题:

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

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

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

类别:

@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

如果您愿意，loadView 中的所有废话都可以用 NIB 替换。只需确保将 datePicker 声明为 IBOutlet。当你想实际使用它时:

- (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];
}