chizzle chizzle - 13 days ago 5
iOS Question

How to pass prepareForSegue: an object

I have many annotations in a mapview (with

rightCalloutAccessory
buttons). The button will perform a segue from this
mapview
to a
tableview
. I want to pass the
tableview
a different object (that holds data) depending on which callout button was clicked.

For example: (totally made up)


  • annotation1 (Austin) -> pass data obj 1 (relevant to Austin)

  • annotation2 (Dallas) -> pass data obj 2 (relevant to Dallas)

  • annotation3 (Houston) -> pass data obj 3 and so on... (you get the
    idea)



I am able to detect which callout button was clicked.

I'm using
prepareForSegue
: to pass the data obj to the destination
ViewController
. Since I cannot make this call take an extra argument for the data obj I require, what are some elegant ways to achieve the same effect (dynamic data obj)?

Any tip would be appreciated.

Answer

Simply grab a reference to the target view controller in prepareForSegue: method and pass any objects you need to there. Here's an example...

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    // Make sure your segue name in storyboard is the same as this line
    if ([[segue identifier] isEqualToString:@"YOUR_SEGUE_NAME_HERE"])
    {
        // Get reference to the destination view controller
        YourViewController *vc = [segue destinationViewController];

        // Pass any objects to the view controller here, like...
        [vc setMyObjectHere:object];
    }
}

REVISION: You can also use performSegueWithIdentifier:sender: method to activate the transition to a new view based on a selection or button press.

For instance, consider I had two view controllers. The first contains three buttons and the second needs to know which of those buttons has been pressed before the transition. You could wire the buttons up to an IBAction in your code which uses performSegueWithIdentifier: method, like this...

// When any of my buttons are pressed, push the next view
- (IBAction)buttonPressed:(id)sender
{
    [self performSegueWithIdentifier:@"MySegue" sender:sender];
}

// This will get called too before the view appears
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([[segue identifier] isEqualToString:@"MySegue"]) {

        // Get destination view
        SecondView *vc = [segue destinationViewController];

        // Get button tag number (or do whatever you need to do here, based on your object
        NSInteger tagIndex = [(UIButton *)sender tag];

        // Pass the information to your destination view
        [vc setSelectedButton:tagIndex];
    }
}

Hope this helps. I've uploaded a tiny test project so you can see what I mean based on simple buttons and a single view app (with an extra view). You can get it here.

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