Code submissions are not being accepted from the iOS app whenever I use quotes.
My answer is not being accepted when code is entered in the iOS app.
If you experience either of the issues highlighted above, chances are that it is directly related to the 'Smart Punctuation' setting on your iOS device.
iOS' 'Smart Punctuation' (see this third-party article for further explanation) specifically impacts writing code.
If enabled, it may be difficult successfully completing exercises in DataCamp from your iOS device, as it replaces 'and " with ‘ and ” (note the angle of the second set of punctuation), for example.
To turn off Smart Punctuation, you can go to Settings > General > Keyboard, and disable the Smart Punctuation toggle for your iOS device.