Calling function in the first view from the other viewcontroller

Question

Hello everyone, I hope that you will succeed in at least a little to clarify me how and what to do, I'm sure I'm wrong, so I really need an expert opinion. I have two viewcontroller together with nibs what I want is to call function that is in first class from another ViewController, the problem is that another viewcontroller manages to call this function but the only thing I can see that is done is NSlog which outputs in the console (which I put in that position to know that the function is called)

example: FirstViewController.m

    -(void)drawingFunction:(NSString*)inputText{
NSLog("Feature was launched");
/* showing stuff in FirstView.xib */
}

SecondViewController.m

-(void)turnOnFunction:(id)sender{
FirstViewController *stuff= [[PrviViewController alloc] init];
[stuff drawingFunction:@"ShowAll"];
}

Basically when I call that function in the PrviViewController.m meaning without reference to the outside e.g.

[self drawingFunction:@"ShowAll"];

everything is well displayed, but when I try to call this function from SecondViewController.m all I see is just a "feature was launched" on the console

I really don't know what to do ...

Answer 1

Hi,

if i get you right, the FirstViewController is on top of the view controller hierarchy (either within a navigation controller or presented modal)? So, if that is the case just creating an instance of SecondViewController and calling a function which should change the user interface on the view which corresponds to SecondViewController will do nothing at all.

You have to present the SecondViewController and its view with presentModalViewController:animated: for instance. After that the view of SecondViewController will be shown and you can do any changes on that view. Also calling the method drawingFunction: will act as you expect it.

Cheers, Andreas

Answer 2

You're confusing instances with classes. You don't send messages (call functions) to classes, you send them to instances.

In this case, you have two entirely separate instances of FirstViewController. The first is created by loading the nib and the second is created in -[SecondController turnOnFunction:]. The drawingFunction: message is being sent to the second instance when you want it to be sent to the first.

You need to link the nib instance of FirstViewController to the SecondController instance. You can do that with an outlet in interface builder or you can assign it when you create the display the SecondController.