Exception breakpoint not working in Xcode11.3

Question

I am using a for-loop to iterate an array. When the index is out of bounds, the exception breakpoint is not stopping at the point of error.

My code

class ViewController: UIViewController
{
    let integers = [1, 2, 3]

    override func viewDidLoad()
    {
        super.viewDidLoad()
        iterate(givenArray: integers)
    }

    func iterate(givenArray: [Int])
    {
        for index in 0...givenArray.count
        {
            print(givenArray[index])
        }
    }
}

I am getting the following error at the console.

1 2 3 Fatal error: Index out of range 2020-01-06 14:29:09.726533+0530 Playground[93060:2221772] Fatal error: Index out of range

I understand the error. My question is that though I have added the Exception breakpoint, why is it not working?

Answer 1

It is not breaking with an Exception breakpoint because a call to fatalError() is not the same as throwing an exception - it is more severe.

You can consider it an indication that your app is in a state it should not try to recover from, and will always result in your app exiting.

There are creative ways[1] of breaking on a call to fatalError, but I think you are better off considering this a code error that should be fixed, and guarding yourself against the error that way, not trying to handle the error in runtime.

[1] - Break on any occurrence of "fatal error: unexpectedly found nil while unwrapping an Optional value"

Answer 2

Remember that errors that occur in Swift are not exceptions, but simply errors (NSError, regardless of which is based on ErrorType, ...).

Do not mix a symbolic breakpoint with an exception breakpoint. Different animals. Keep this in mind. When you try to set an exception checkpoint in Xcode, there is no Swift. Probably the main reason is that abandoned errors are no exception, and they have not figured out where else to put.Add a point manually!!