Uncaught exception in xcode - objective-c

Question

I'm new to Xcode and therefor i'm to build small apps. i've recently got a problem, i just cant seem to find.
i've made a send button, that is going to send me from ViewController2 to ViewController.
Viewcontroller2.h
#interface ViewController2 : UIViewController {
ViewController *viewController;
}
- (IBAction)SaveData:(id)sender;
ViewController.m
- (IBAction)SaveData:(id)sender {
viewController = [[ViewController alloc]initWithNibName:#"ViewController" bundle:nil];
[self.view addSubview: viewController.view];
}
i've checked every connection in storyboard is correct, but i still get this error.
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

Answer 1

I'm not 100% sure on what exactly is causing the error. As discussed in comments, segues are a much easier way of dealing with transitions between view controllers, so unless you have a particularly good reason to not use segues, I'd start learning segues (since you're learning new stuff anyway).
The error, however, is probably related to this:
[self.view addSubview: viewController.view];
When you do this, what you seem to be trying to do is taking the view (visual part) and adding it to the view of ViewController2. Meanwhile, ViewController2 doesn't have any controls set up for that view, and you wrote a lot of code in viewController that is pointless because you're never actually instantiating a view with that controller.
The above line I posted should be replaced with the following if you're not going to use segues:
[self presentViewController:viewController animated:YES completion:nil];
And this should be called after setting the properties on viewController for the data you wish to pass.
Better, however, is to just use storyboard segues. No matter how you call your segue, you're going to pass data by overriding the prepareForSegue:sender: method:
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if([[segue identifier] isEqualToString:#"segueNameHere"]) {
ViewController* viewController = [segue destinationViewController];
// now set the properties of viewController
}
}