How to add input device for capturesession in Swift2 and Xcode7 beta?

Question

I am following this tutorial to make a camera app, but the tutorial is in Swift and I am using Xcode 7 beta and Swift2.

http://jamesonquave.com/blog/taking-control-of-the-iphone-camera-in-ios-8-with-swift-part-1/

I heard that Swift2 has a different error-handling method now, so I guess this part of code needs to be changed. But I am not sure how. Can anyone help me with this? Thanks!

var err : NSError? = nil
        captureSession.addInput(AVCaptureDeviceInput(device: captureDevice, error: &err))

        if err != nil {
            println("error: \(err?.localizedDescription)")
        }

Answer 1

In order to get the code you posted to match the new error handling requirements in swift 2 you need to replace your lines of code with the following:

var err : NSError? = nil
do {
    let input = try AVCaptureDeviceInput(device: captureDevice)
    captureSession.addInput(input)
} catch _ {
    print("error: \(err?.localizedDescription)")
}

The reason for this change is that Apple has changed the way you need to handle errors in order to make the coding less error prone. Now you need to have a do catch statement for any call that is going to throw an error. The call that could throw and error needs to be in the do statement and the error handling needs to be found in the catch statement. There a bit more detail as to the reason for this change in the following link:

https://www.hackingwithswift.com/new-syntax-swift-2-error-handling-try-catch

Answer 2

Explanation of the new Swift error handling - Error-Handling in Swift-Language

let captureSession = AVCaptureSession()
let captureDevice: AVCaptureDevice
do {
    let input = try AVCaptureDeviceInput(device: captureDevice)
    captureSession.addInput(input)
}