How can we use Assets Catalog Colors Sets

问题

I usually use custom UIColors on iOS using extensions with Swift but now with iOS11/XCode9 we can create Colors Sets. How can we use them?

Update - Tip

As @Cœur says we can drag&drop de color, and use it like a UIColor object and a possible solution could be use it as a extension:

Or as a constant:

Now I wanna know if we can access them like an UIImage access to an Asset Image or not, like:

UIImage(named: "image-name") -> UIColor(named: "color-name")

回答1:

UIColor(named: "myColor")

Source: WWDC 2017 Session 237 —— What's New in MapKit

Caveat: Your project's Deployment Target needs to be set to iOS 11.0.

回答2:

(short answer to the question update: there is UIColor(named: "MyColor") in Xcode 9.0)

Answering the original question:

you create your color set

you find your color among your snippets and you drag-n-drop it

it will translate to a color literal when looking at the source code:

#colorLiteral(red: 0, green: 0.6378085017, blue: 0.8846047521, alpha: 1)

You notice how the values of red, green and blue are different? It's because I defined them using Color Space Display P3, but the colorLiteral is using Color Space sRGB.

回答3:

Short Version

Add a colour set to an asset catalog, name it and set your colour in the attributes inspector, then call it in your code with UIColor(named: "MyColor").

Full Instructions

In the asset catalog viewer, click the plus button at the bottom right of the main panel and choose New Color Set
Click on the white square, and select the Attributes Inspector (right-most icon in the right pane)
From there you can name and choose your colour.
To use it in your code, call it with UIColor(named: "MyColor"). This returns an optional, so you'll need to unwrap it in most cases (this is probably one of the few cases where a force unwrap is acceptable, given you know the colour exists in your asset catalog).

回答4:

You need to use UIColor(named: "appBlue").

And you can create a function in UIColor extension for simple access.

enum AssetsColor {
   case yellow
   case black
   case blue
   case gray
   case green
   case lightGray
   case seperatorColor
   case red
}

extension UIColor {

static func appColor(_ name: AssetsColor) -> UIColor? {
    switch name {
    case .yellow:
        return UIColor(named: "appYellow")
    case .black:
        return UIColor(named: "appBlack")
    case .blue:
        return UIColor(named: "appBlue")
    case .gray:
        return UIColor(named: "appGray")
    case .lightGray:
        return UIColor(named: "appLightGray")
    case .red:
        return UIColor(named: "appRad")
    case .seperatorColor:
        return UIColor(named: "appSeperatorColor")
    case .green:
        return UIColor(named: "appGreen") 
    }
}

You can use it like this

userNameTextField.textColor = UIColor.appColor(.gray)

回答5:

 // iOS
 let color = UIColor(named: "SillyBlue")

 // macOS
 let color = NSColor(named: "SillyBlue")

回答6:

You can use this way for simple accessing (swift 4)

enum AssetsColor: String {
    case backgroundGray
    case blue
    case colorAccent
    case colorPrimary
    case darkBlue
    case yellow
}

extension UIColor {
    static func appColor(_ name: AssetsColor) -> UIColor? {
         return UIColor(named: name.rawValue)
    }
}

回答7:

For your question if you can access color assets like the image using literal, as of xcode 10.2 you can type in colorliteral, then you can pick the color you want to use that is under your asset manager.

sample snippet