Modified SwiftGen xcassets template to make static constant of type UIColor or NSColor

colors-swift5.stencil

// swiftlint:disable all
// Generated using SwiftGen — https://github.com/SwiftGen/SwiftGen

{% if catalogs %}
{% set enumName %}{{param.enumName|default:"Colors"}}{% endset %}
{% set colorType %}{{param.colorTypeName|default:"Color"}}{% endset %}
{% set forceNamespaces %}{{param.forceProvidesNamespaces|default:"false"}}{% endset %}
{% set accessModifier %}{% if param.publicAccess %}public{% else %}internal{% endif %}{% endset %}
#if os(macOS)
  import AppKit
#elseif os(iOS)
  import UIKit
#elseif os(iOS) || os(tvOS) || os(watchOS)
  import UIKit
#endif

// swiftlint:disable superfluous_disable_command file_length implicit_return

// MARK: - Color Assets

{% macro enumBlock assets %}
  {% call casesBlock assets %}
  {% if param.allValues %}

  // swiftlint:disable trailing_comma
  {% if resourceCount.color > 0 %}
  {{accessModifier}} static let allColors: [{{colorType}}] = [
    {% filter indent:2 %}{% call allValuesBlock assets "color" "" %}{% endfilter %}
  ]
  {% endif %}
  // swiftlint:enable trailing_comma
  {% endif %}
{% endmacro %}
{% macro casesBlock assets %}
  {% for asset in assets %}
  {% if asset.type == "color" %}
  {{accessModifier}} static let {{asset.name|swiftIdentifier:"pretty"|lowerFirstWord|escapeReservedKeywords}} = Color(named: "{{asset.value}}")
  {% elif asset.items and ( forceNamespaces == "true" or asset.isNamespaced == "true" ) %}
  {{accessModifier}} enum {{asset.name|swiftIdentifier:"pretty"|escapeReservedKeywords}} {
    {% filter indent:2 %}{% call casesBlock asset.items %}{% endfilter %}
  }
  {% elif asset.items %}
  {% call casesBlock asset.items %}
  {% endif %}
  {% endfor %}
{% endmacro %}
{% macro allValuesBlock assets filter prefix %}
  {% for asset in assets %}
  {% if asset.type == filter %}
  {{prefix}}{{asset.name|swiftIdentifier:"pretty"|lowerFirstWord|escapeReservedKeywords}},
  {% elif asset.items and ( forceNamespaces == "true" or asset.isNamespaced == "true" ) %}
  {% set prefix2 %}{{prefix}}{{asset.name|swiftIdentifier:"pretty"|escapeReservedKeywords}}.{% endset %}
  {% call allValuesBlock asset.items filter prefix2 %}
  {% elif asset.items %}
  {% call allValuesBlock asset.items filter prefix %}
  {% endif %}
  {% endfor %}
{% endmacro %}
// swiftlint:disable identifier_name line_length nesting type_body_length type_name
{{accessModifier}} enum {{enumName}} {
  {% if catalogs.count > 1 or param.forceFileNameEnum %}
  {% for catalog in catalogs %}
  {{accessModifier}} enum {{catalog.name|swiftIdentifier:"pretty"|escapeReservedKeywords}} {
    {% filter indent:2 %}{% call enumBlock catalog.assets %}{% endfilter %}
  }
  {% endfor %}
  {% else %}
  {% call enumBlock catalogs.first.assets %}
  {% endif %}
}
// swiftlint:enable identifier_name line_length nesting type_body_length type_name

// MARK: - Implementation Details
{% if resourceCount.color > 0 %}

#if os(macOS)
{{accessModifier}} typealias Color = NSColor
#elseif os(iOS) || os(tvOS) || os(watchOS)
{{accessModifier}} typealias Color = UIColor
#endif

{{accessModifier}} extension {{colorType}} {
  @available(iOS 11.0, tvOS 11.0, watchOS 4.0, macOS 10.13, *)
  convenience fileprivate init(named: String) {
    let bundle = {{param.bundle|default:"BundleToken.bundle"}}
    #if os(iOS) || os(tvOS)
    self.init(named: named, in: bundle, compatibleWith: nil)!
    #elseif os(macOS)
    self.init(named: NSColor.Name(named), bundle: bundle)!
    #elseif os(watchOS)
    self.init(named: named)!
    #endif
  }
}
{% endif %}

{% if not param.bundle %}

// swiftlint:disable convenience_type
private final class BundleToken {
  static let bundle: Bundle = {
    Bundle(for: BundleToken.self)
  }()
}
// swiftlint:enable convenience_type
{% endif %}
{% else %}
// No assets found
{% endif %}

You don't have to call .color every time now.
Output:

internal enum Colors {
  internal static let primary = Color(named: "Primary")
}