Transfer data between view controllers, using storyboard and TabBarController - ios

Question

I have a Login ViewController and a Tab Bar Controller with two “tabs”. Now I want to transfer data from Login VC to one of the TabBar VCs. If the Login VC receives certain information, it should call a method in one of the TabBar VCs. I created all the view controllers with the storyboard. I don’t use programmatically segue of the view controllers.
Thus I tried to use a protocol and delegate. But when I’m coding something like this:
LoginViewController *loginVC = [[LoginViewController alloc] init];
loginVC.myTestDelegate = self;
It creates a new instance of the view controller and didn’t take the existing where it gets the information to call the method.
Is there any way to fix that problem? Or do I have to use programmatically segues?
If yes how can I change the tabs programmatically?

Answer 1

YourViewController* pdvc = [[YourViewController alloc] init];
pdvc.selectedImage = selectedPhoto;
pdvc.selectedObj = theObject;
pdvc.selectedImg = theImage;
[self presentViewController:pdvc animated:YES completion:nil];
or
YourViewController* nextView = [self.storyboard
instantiateViewControllerWithIdentifier:
#"YOUR_NEXT_STORYBOARD_ID"];
[nextView setYOUR_VALUE:value];
[self presentViewController:nextView
animated:YES
completion:nil];

Answer 2

If you want to navigate to the same viewController to which you want to pass data when your loginViewController receives data, then you can use following method which is triggered when the transition begins from the current view.
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"yourViewIdentifier"]) {
RecipeDetailViewController *destViewController = segue.destinationViewController;
destViewController.recievingData = yourDataToPass;
}
}
Second method is to add observers using NSNotificationCenter class:
Add following method to your TabBar VCs in viewDidLoad: method
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(viewDidReceivedData:)
name:"ReceivedData" object:nil];
And implement following method:
- (void)viewDidReceivedData:(id)receivedData{
}
In your loginViewController,once you receive necessary information to pass to the viewcontroller call following:
[[NSNotificationCenter defaultCenter] postNotificationName:#"ReceivedData" object:yourData];
Refer: http://www.hpique.com/2013/12/nsnotificationcenter-part-1/