在视图控制器之间传递数据不起作用

Question

I am attempting to pass the label for a given selected cell to a different view controller...

ListViewController.m

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

NSIndexPath *selectedIndexPath = [self.tableView indexPathForSelectedRow];
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:selectedIndexPath];

UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Storyboard" bundle: nil];
DetailViewController *viewController = [storyboard instantiateViewControllerWithIdentifier:@"DetailVC"];
viewController.venueName = cell.textLabel;
[self.navigationController pushViewController:viewController animated:YES];

}

Here is my DetailViewController:

.h

@interface DetailViewController : UIViewController {

    IBOutlet UILabel *venueName;
}

@property (nonatomic, strong) IBOutlet UILabel *venueName;

venueName never gets the data. In my .m I also synthesize the venueName.

Answer 1

This happens because your UILabel outlet is not connected at the time you set a string for it. I recommend you to create a string property to store the value and, in viewDidLoad in DetailViewController, you set the string to venueName. Cheers!!

Answer 2

您需要像设置和获取文本一样修改以下内容：-

viewController.venueName.text = cell.textLabel.text;

Answer 3

So venueName , which is a pointer to a label , is made to point to an existing label that's part of a table cell. This is obviously wrong -- you don't mean to use the actual label from the table cell, but rather the text stored in it. Both the other answers here are correct: you surely mean to assign the text property of one label to that of the other, and the label that outlet viewController.venueName is connected to hasn't been created at the time this code executes.

The immediate thing you should do to fix your code is to assign the data in question (ie cell.textLabel.text ) to a string property in the destination view controller. Have the -viewDidLoad or -viewWillAppear method in that controller set the text property of the venueLabel label. Either of those methods will be called after the view hierarchy is instantiated.