Question

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viewWillDisappear方法被触发，如何获取此文本字段的值，就是保存数据。

Answer 1

有几种方法可以做到这一点。最好的方法是使用委托模式或通知系统。

您选择哪一个取决于您的情绪。如果您只是希望“父控制器”知道该值，请使用委托方法。

使用委托或通知可以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，从头顶开始！

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
}

如何访问父视图控制器？

1 个答案: