SwiftUI 崩溃预览中的资产目录 colors 的颜色扩展

Question

The below example compiled and ran fine in simulator/device, but runs into problems in canvas preview. (I have tried clearing cache and derived data)

extension Color {
  static let primary = Color("primary")
  static let test = Color(red: 1, green: 0, blue: 0)
}

This works fine in canvas preview:

Text("hi").background(Color.test)

But color assets crashes preview:

Text("hi").background(Color.primary)


Compiling failed: cannot convert return expression of type 'AnyView' to return type 'some View'

(Also as a side note, this seems to work just fine Text("hi").background(Color("primary")) )

Answer 1

There is SwiftUI standard Color.primary (see below), so I assume the issue is due to ambiguity.

 @available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *) extension Color { /// A set of colors that are used by system elements and applications. public static let clear: Color... public static let primary: Color // << here !!

use instead unique static var name for your custom color, like

extension Color {
  static let myPrimary = Color("primary")               // << here !!
  static let test = Color(red: 1, green: 0, blue: 0)
}

Tested with Xcode 11.4