prepareForSegue and popViewController compatibility

问题

The question

I'm working on a iOS app and i have 3 consecutive ViewControllers:

TableViewController --> DetailViewController --> ImageViewController

I perform de forward Segue with a button (Just control drag on Storyboard) and to go back I have a custom back button with

[self.navigationController popViewControllerAnimated:YES];

To send data forward I use

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    [segue.destinationViewController someFunction];
}

To send data to the parent ViewController I can use prepareForSegue in the DetailViewController, but it doesn't work in the ImageViewController and there I have to use Notifications.

It's OK if I use prepareForSegue to send data with popViewControllerAnimated?

Should I use Notifications in both cases?

Some code

What I have in the DetailViewController is a button that perform the Segue to the ImageViewController (just control drag on Storyboard) and a Back Button with:

- (IBAction)backAction:(id)sender {
     [self.navigationController popViewControllerAnimated:YES];
}

and then the function:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if([segue.identifier isEqualToString:@"forwardSegue"]) {
        [segue.destinationViewController someFuntionToImageViewController];
    } else {
        [segue.destinationViewController someFuntionToParentViewController];
    }
}

I noticed that I can't assign a segue.identifier to the popViewController action.

回答1:

Apple recommends the following way to pass data between view controllers that are navigated by segues:

To pass data forward:

You declare a property on the destination vc and set its value in the prepareForSegue method. (So kind of the way you did it)

@interface SomeViewController

@property (strong, nonatomic) VeryImportantData *data;
//...
@end

@implementation SourceVC

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    VeryImportantData *theData = ...;
    segue.destinationViewController.data = theData;
}

To pass data back

You declare a delegate protocol. This could look like this:

@protocol SomeViewControllerDelegate
- (void)someViewController:(SomeViewController *) someVC didFinishWithData:(SomeData *) data;
@end

Your destination vc provides a delegate property:

@property (weak, nonatomic) id<SomeViewControllerDelegate> delegate;

The destination vc calls it's delegates method once it's ready to be closed:

@implementation SomeViewController

- (void) close
{
    [delegate someViewController:self didFinishWithData:self.data];
}

And your source controller implements the protocol and sets itself as delegate of the destination vc in the prepareForSegue method.

@implementation SourceVC

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    segue.destinationViewController.delegate = self;
}


//...
- (void)someViewController:(SomeViewController *) someVC didFinishWithData:(SomeData *) data
{
    self.receivedData = data;
    [self.navigationController popViewControllerAnimated:YES];
}

来源：https://stackoverflow.com/questions/13110123/prepareforsegue-and-popviewcontroller-compatibility

标签

iphone

ios

xcode

uistoryboardsegue