Wordpress-ios: [Xcode 12] Fix miscellaneous build warnings

[frosty]

There are a few random Xcode 12 / iOS 14 build warnings that we should address:

• [x] System Blur Style before iOS 13.0
• [x] Non-Default Vibrancy Style before iOS 13.0
• [x] Plain Style unsupported in a Navigation Item
• [x] MinimumOsVersion of '4.0' is less than the value of IPHONEOS_DEPLOYMENT_TARGET '11.0'
• [x] Backward matching of the unlabeled trailing closure is deprecated; label the argument with 'failure' to suppress this warning
• [x] Implicit conversion from enumeration type 'enum UITableViewStyle' to different enumeration type 'UISplitViewControllerStyle' (aka 'enum UISplitViewControllerStyle')
• [x] The image set name "democover01" (and "democover02") is used by multiple image sets.

The first two appear to be present in CollapsableHeaderViewController.xib
The third is in LayoutPickerStoryboard.storyboard

[hypest]

👋 @guarani , can you have a look here regarding the Gutenberg Integration side of things and share a quick assessment of how many warnings are related to Gutenberg and what do you think the effort/difficulty will be to address them? Asking so we can plan to address them. Thanks!

[guarani]

We have lots of Pods that need their deployment target updated, e.g.:

The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.0.99.

some are forks, some are Gutenberg RN pods, others are regular pods. While we could fix this in the Podfile, the best solution might be to look for new versions of affected Pods (and update our forks).

[guarani]

Another warning we've been seeing a lot lately (not directly related to Gutenberg) relates to Core Data:

AbstractPost.revisions is using a nil or insecure value transformer. Please switch to NSSecureUnarchiveFromDataTransformerName or a custom NSValueTransformer subclass of NSSecureUnarchiveFromDataTransformer 

the fix involves updating the .xcdatamodel to use NSSecureUnarchiveFromDataTransformer:

-        <attribute name="options" optional="YES" attributeType="Transformable"/>
+        <attribute name="options" optional="YES" attributeType="Transformable" valueTransformerName="NSSecureUnarchiveFromDataTransformer"/>

Also, as @danielebogo pointed out offline, custom types have to have a custom ValueTransformer (and all your entities must conform to NSSecureCoding).
And as @leandroalonso said offline, we might have to add this change to older data model versions to avoid warnings when running (migration) tests.

[frosty]

FYI we have separate issues for both of these items:

• CocoaPods deployment targets
• Core Data transformers

[frosty]

And as @leandroalonso said offline, we might have to add this change to older data model versions to avoid warnings when running (migration) tests.

I don't think changing older models is a good idea... once they're released, they should generally be left alone. I don't think potentially having some warnings during tests is an issue.

[guarani]

FYI we have separate issues for both of these items:

Good to know! Hadn't looked for an issue.