如何访问父视图控制器？

发布于 2024-08-31 11:50:45 字数 554 浏览 3 评论 0原文

我正在使用此代码在 ViewControllerA 中推送视图控制器：

DatePickerViewController *viewController = [[DatePickerViewController alloc] initWithNibName:@"DatePickerViewController" bundle:nil];
NSMutableArray *info = [[NSMutableArray alloc] initWithObjects:@"Exam Duration",nil];
[viewController setInfo:info];
[info release];
[self.navigationController pushViewController:viewController animated:YES];
[viewController release];

在滑入的 DatePickerViewController 中，它有一个文本字段。在 ViewControllerA 中，一旦触发 viewWillDisappear 方法，如何获取此文本字段的值，它是为了保存数据。

原文

I am using this code to push a view controller in ViewControllerA:

DatePickerViewController *viewController = [[DatePickerViewController alloc] initWithNibName:@"DatePickerViewController" bundle:nil];
NSMutableArray *info = [[NSMutableArray alloc] initWithObjects:@"Exam Duration",nil];
[viewController setInfo:info];
[info release];
[self.navigationController pushViewController:viewController animated:YES];
[viewController release];

In the DatePickerViewController that is slid in, it has a text field. In ViewControllerA how can I get the value of this text field once the viewWillDisappear method is fired, it's to save data.

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画尸师 2024-09-07 11:50:45

有几种方法可以做到这一点。最好是使用委托模式或通知系统。

您选择哪一种取决于您的愿望。如果您只想让“父控制器”了解该值，请使用委托方法。

使用委托或通知创建松散耦合的结构并使可重用的类成为可能。

编辑：一些示例代码。当心：未经测试，来自我的头脑！

DatePickerViewController.h

@protocol DatePickerViewControllerDelegate
    -(void)datePicker:(DatePickerViewController *)picker pickedDate:(NSDate *)date;
@end

DatePickerViewController.m

- (void)viewWillDisappear:(BOOL)animated {
    [self.delegate datePicker:self pickedDate:theDate]; //Delegate is an ivar
    [super viewWillDisappear:animated];
}

ViewControllerA.m

//
DatePickerViewController *viewController = [[DatePickerViewController alloc] initWithNibName:@"DatePickerViewController" bundle:nil];
NSMutableArray *info = [[NSMutableArray alloc] initWithObjects:@"Exam Duration",nil];
[viewController setInfo:info];
[info release];
[viewController setDelegate:self]; // Set the delegate of the date picker
[self.navigationController pushViewController:viewController animated:YES];
[viewController release];
//

-(void)datePicker:(DatePickerViewController *)picker pickedDate:(NSDate *)date; {
     //Deal with the new date here
}

There are several ways to do this. Best would be to use a delegate pattern or a notification system.

Which one you choose depends on your whishes. If you just want the 'parent controller' to know about the value, use a delegate method.

Using delegates or notifications creates a loosely coupled structure and makes reusable classes possible.

EDIT: Some sample code. Beware: untested and from the top of my head!

DatePickerViewController.h

@protocol DatePickerViewControllerDelegate
    -(void)datePicker:(DatePickerViewController *)picker pickedDate:(NSDate *)date;
@end

DatePickerViewController.m

- (void)viewWillDisappear:(BOOL)animated {
    [self.delegate datePicker:self pickedDate:theDate]; //Delegate is an ivar
    [super viewWillDisappear:animated];
}

ViewControllerA.m

//
DatePickerViewController *viewController = [[DatePickerViewController alloc] initWithNibName:@"DatePickerViewController" bundle:nil];
NSMutableArray *info = [[NSMutableArray alloc] initWithObjects:@"Exam Duration",nil];
[viewController setInfo:info];
[info release];
[viewController setDelegate:self]; // Set the delegate of the date picker
[self.navigationController pushViewController:viewController animated:YES];
[viewController release];
//

-(void)datePicker:(DatePickerViewController *)picker pickedDate:(NSDate *)date; {
     //Deal with the new date here
}

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