Update a label through button from different view

Question

How to update a label by button clicks when they both are in different classes of uiview controller...when button is clicked,the label should be update...i tried many times.

Answer 1

Not sure if it's a good solution, but you could store the text in a global NSString when clicking on the button, then put that string into your label when loading the second view.

Answer 2

There are a few ways to maintain communication between views (view controllers, actually) in iOS. Easiest of which for me is sending notifications. You add an observer for a notification in the view you want to make the change, and from the view that will trigger the change, you post the notification. This way you tell from ViewController B to ViewController A that "something is ready, make the change"

This, of course, requires your receiver view to be created and already be listening for the notification.

In ViewController B (sender)

- (void)yourButtonAction:(id)sender
{
    [[NSNotificationCenter defaultCenter] postNotificationName:@"theChange" object:nil];
}

In ViewController A (receiver) Add the observer to listen for the notification:

- (void)viewDidLoad
{
    //.........
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(makeTheChange) name:@"theChange" object:nil];
}

Do NOT forget to remove it (in this case, on dealloc)

- (void)dealloc
{
     [[NSNotificationCenter defaultCenter] removeObserver:self name:@"theChange" object:nil];
     [super dealloc];
}

And finally, the method that will update your label

- (void)makeTheChange
{
    yourLabel.text = @"your new text";
}