Generate a Color class extension with asset colors used in storyboard

[phimage]

only for iOS11,tvOS11,macOS10.13 https://littlebitesofcocoa.com/312-asset-catalog-improvements

Add a Color xml class to read color from storyboards

For each OS

• I create an extension for the XXXColor class if there is at least one color
• and in there I create a constant variable for each asset color. An asset color have a name and are not a "System" one (so I have filtered system color like labelColor, etc...)

For other colors I think about adding it in controller.

See one of the Storyboards.swiftfile

I use the generated constant in demo app in MainViewController.swift

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This new functionality of Xcode9/iOS11 seems to have some bugs

• In Xcode if we have multiple asset with same color name, sometimes the interface builder use a color from another asset.
  • workaround, use a shared asset between device and use idiom (not universal) if we want a different color by device
• When using an asset color in view background, the color set by prepare(for segue:seems to not be taken into account on iOS and tvOS.
  • maybe the color is set later in view loading process if this case.
  • workaround: create a color variable in destination controller, and in viewDidAppear (and maybe in viewDidLoad) use the color to set as view background color

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An other approach is to generate code from asset. I want to make this generation optional later.

Maybe with a json config file (like #55), now with swift 4 this is easier

[krzyzanowskim]

Nice. How can we workaround the know issues?

[krzyzanowskim]

I'd love to merge it. Can you please add README entry for the feature?

[phimage]

I will And re-test with the latest Xcode