Adding optional error handler parameter to DFUFirmware initializers.

[appfactoryCo]

Hello there,

Thank you for creating this useful library.

I was trying to create a firmware file by passing a url. I noticed that I didn't get enough information about the kind of error that happened when using the DFUFirmware initializer. For example, when I passed it a url to a zip file like this:

let firmware = DFUFirmware(urlToZipFile: firmwareUrl)

Then, I found this error in the logs:

Error while creating ZIP stream: The operation couldn’t be completed. (NordicDFU.DFUStreamZipError error 0.)

I had no idea what that meant, and there was no initializer that would give my app an error. So, I added errorHandler parameter to the DFUFirmware initializers to get some errors back to my app:

@objc convenience public init?(urlToZipFile: URL, errorHandler: ((String) -> ())?)

For example, now I can do something like this:

let firmware = DFUFirmware(urlToZipFile: firmwareUrl, errorHandler: { [weak self]
                    errorMsg in
                    DispatchQueue.main.async { // Handle creating firmware errors in main thread
                        self?.raiseAlert(title: "Sorry", message: errorMsg)
                    }
                })

or

let firmware = DFUFirmware(urlToZipFile: firmwareUrl, errorHandler: nil)

Doing so helped me figure out what the error was. It was "No manifest file found," and now I can let the app display this error back to the user.

I hope this little contribution is useful.

Thanks a lot.

[CLAassistant]

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[philips77]

I think we'll close this PR and try coming up with something similar to solve your problem. The init may throw an error instead of returning nil.

I'll just leave it open for now not to forget about it.

[philips77]

Closed with #486.