CODEWITHSUNDEEP
iosobjective-c
user3672051
user3672051

Reputation:

addChildViewController giving NSException error?

I am new to using this method so I could be doing this completely wrong so here is my code:

@property (nonatomic, weak) ConverterViewController *converterViewController;
@property (nonatomic, weak) CalculatorViewController *calculatorViewController;

If I am understanding this code correctly, these are acting as references to Two different ViewControllers.

Then I have this in my viewDidAppear method:

[self addChildViewController:_converterViewController];
[_converterViewController didMoveToParentViewController:self];
[self.view addSubview:_converterViewController.view];

I am getting an NSException at the first line when I try and add it as a child view controller. So not knowing whether or not this should then call some methods in my ConverterViewController class I put some breakpoints within that class both the initWithNibName and viewDidLoad methods and I found that neither of these methods are being called, so Im not exactly sure what is wrong. Then again Im not really sure what could go wrong so any help is greatly appreciated.

This is all I get from the console:

libc++abi.dylib: terminating with uncaught exception of type NSException

Upvotes: 2

Views: 282

Answers (1)

staticVoidMan
staticVoidMan

Reputation: 20234

Updated Answer:

[self addChildViewController:_converterViewController]; does not create the converterViewController.
It simply takes the converterViewController object and adds it as a childViewController to self.

You will need to allocate memory and instantiate the object converterViewController before -addChildViewController: or else it's value will be nil and nothing will happen.

So... something this:

_converterViewController = [[ConverterViewController alloc] initWithNibName:@"ConverterViewController"
                                                                     bundle:nil];

//now... adding it as childViewController should work
[self addChildViewController:_converterViewController];
[_converterViewController didMoveToParentViewController:self];
//optional: give it a frame explicitly so you may arrange more childViewControllers
//[_converterViewController.view setFrame:CGRectMake(0,0,100,100)];
[self.view addSubview:_converterViewController.view];

Upvotes: 2

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