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Hacktoberfest #3: iOS 11 Deprecation Warnings

October 21, 2018

This week, I found an issue in an iOS-browser called Brave. The issue contained 4 warnings that had to be fixed, and I asked to work on it. Here is the list of warnings:

  • ‘automaticallyAdjustsScrollViewInsets’ was deprecated in iOS 11.0: Use UIScrollView’s contentInsetAdjustmentBehavior instead.
  • ‘touchIDNotAvailable’ was deprecated in iOS 11.0: use LAErrorBiometryNotAvailable.
  • ‘touchIDNotEnrolled’ was deprecated in iOS 11.0: use LAErrorBiometryNotEnrolled.
  • ‘touchIDLockout’ was deprecated in iOS 11.0: use LAErrorBiometryLockout.

After I was approved to work on it, I set up the project on my local machine, installed dependencies using Carthage and built the app to make sure everything works.

Next, I found the warnings I needed to fix in the code, analyzed the code, and started my research on how to fix them.

‘automaticallyAdjustsScrollViewInsets’ was deprecated in iOS 11.0: Use UIScrollView’s contentInsetAdjustmentBehavior instead.

Here is a definition of automaticallyAdjustsScrollViewInsets:

A Boolean value that indicates whether the view controller should automatically adjust its scroll view insets. (Apple documentation)

However, it’s been deprecated since iOS 11, so UIScrollView.ContentInsetAdjustmentBehavior should be used instead.

This property specifies how the safe area insets are used to modify the content area of the scroll view. The default value of this property is UIScrollView.ContentInsetAdjustmentBehavior.automatic. (Apple documentation)

There were two ViewControllers that used automaticallyAdjustsScrollViewInsets, and here is how it was used:

automaticallyAdjustsScrollViewInsets = false

and I changed it into:

if #available(iOS 11.0, *) {
    scrollView?.contentInsetAdjustmentBehavior = .never        
} else {            
    automaticallyAdjustsScrollViewInsets = false       
}

Fixed ✅

touchID deprecation warnings

If you are using LocalAuthentication framework, iOS developers shouldn’t use any touchID error codes since iOS 11 was released because there are 2 ways of authentication in iOS now: TouchID and FaceID, and it is not efficient to have different errors for TouchID/FaceID failures.

The first thing that concerned me about these warnings was that there wasn’t any line of code or file specified in these warnings. I tried to search for any mentions of touchIDNotAvailable, touchIDNotEnrolled and touchIDLockout in the repository, however, I didn’t find any usage of these properties anywhere in the code!

The only related thing I found in the code was:

DispatchQueue.main.async {
  switch code {
    case .userFallback, .biometryNotEnrolled, .biometryNotAvailable,      .biometryLockout:
        fallback?()
    case .userCancel:
        cancel?()
    default:
        cancel?()
  }
}

where code is instance of LAError.Code

And it confused me because it uses LAErrorBiometryNotAvailable, LAErrorBiometryNotEnrolled, and LAErrorBiometryLockout as it was required in the warning.

I did a research about these warnings, and I found out that, actually, it is a Swift compiler bug. That’s why I informed project contributors about that, and I created a Pull Request with my fix for the first warning.

Here are some outcomes of this week:

  • Fixed iOS 11 deprecation warning: ‘automaticallyAdjustsScrollViewInsets’ was deprecated in iOS 11.0: Use UIScrollView’s contentInsetAdjustmentBehavior instead.
  • Researched touchID iOS 11 deprecation warnings, and learned that there is a bug in Swift compiler
  • Communicated with project maintainers and contributors