Question

我查看了与viewcontrollers之间传递数据相关的所有其他帖子，但没有一个是针对我的问题。

我想将有人在mapKit中点击的注释标题传递给新的viewcontroller，以便我可以在新的viewcontroller中使用该标题。我正在使用calloutAccessoryControlTapped方法检测某人是否点击了detailDisclosure按钮，然后使用以下代码将标题添加到第二个viewcontroller中的属性（名为detailViewController）：

- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control
{
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main_iPad" bundle:nil];
    detailViewController *viewController = (detailViewController *)[storyboard instantiateViewControllerWithIdentifier:@"detailViewController"];

    detailViewController *detailView = [[detailViewController alloc] init];

    // THIS IS WHERE I SET THE ANNOTATION TITLE TO THE PROPERTY IN THE SECOND VIEWCONTROLLER
    detailView.titleTime = view.annotation.title; 

    NSLog(@"view.annotation.title: %@", view.annotation.title); // SHOWS THE TITLE
    NSLog(@"detailView.titleTime: %@", detailView.titleTime);   // SHOWS THE TITLE


    // HERE I PRESENT NEW VIEWCONTROLLER (HOPING THE TITLE IS PASSED)
    [self presentViewController:viewController animated:YES completion:nil];

}

在第二个viewcontroller（detailViewController）中，我在viewDidLoad方法中有这个：

- (void)viewDidLoad
{
[super viewDidLoad];

// set the Title Label to the titleTime (passed from the mainViewController)
self.titleForDetail.text = self.titleTime;
NSLog(@"titleForDetail.text %@:", titleForDetail.text); // THIS IS NULL
 NSLog(@"titleForDetail.text %@:", titleTime); // THIS IS NULL
}

为什么self.titleForDetail.text和self.titleTime NULL？为什么没有从原来的viewController传递任何内容？

Answer 1

在calloutAccessoryControlTapped中，代码在titleTime上设置detailView属性，但随后展示viewController（没有设置属性）。

将礼物更改为：

[self presentViewController:detailView animated:YES completion:nil];

看起来您不需要storyboard和viewController变量，因此您可以从该方法中删除它们。

Answer 2

您的代码中包含以下两行：

    detailViewController *viewController = (detailViewController *)[storyboard instantiateViewControllerWithIdentifier:@"detailViewController"];
    detailViewController *detailView = [[detailViewController alloc] init];

在其余代码中，您有时使用viewController，有时使用detailView。你应该只有其中一个，它应该像你对viewController一样实例化：

- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control
{
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main_iPad" bundle:nil];
    detailViewController *detailView = (detailViewController *)[storyboard instantiateViewControllerWithIdentifier:@"detailViewController"];
    detailView.titleTime = view.annotation.title;
    [self presentViewController:detailView animated:YES completion:nil];
}

尝试在viewcontrollers之间传递数据 - 将注释标题传递给新的viewcontroller

2 个答案: