如果我有SwiftUI Color：
let col: Color = Color(red: 0.5, green: 0.5, blue: 0.5)
如何从col获取RGB分量？
也许像这样：
print(col.components.red)
在UIKit中，我可以使用UIColor.getRed，但SwiftUI中似乎没有等效项。
答案 0 :(得分：7)
现在有一个新的初始化程序，它需要一个Color并为 iOS 返回一个UIColor，或者为 macOS 返回一个NSColor。在这些帮助下，您可以实现以下扩展：
import SwiftUI
#if canImport(UIKit)
import UIKit
#elseif canImport(AppKit)
import AppKit
#endif
extension Color {
var components: (red: CGFloat, green: CGFloat, blue: CGFloat, opacity: CGFloat) {
#if canImport(UIKit)
typealias NativeColor = UIColor
#elseif canImport(AppKit)
typealias NativeColor = NSColor
#endif
var r: CGFloat = 0
var g: CGFloat = 0
var b: CGFloat = 0
var o: CGFloat = 0
guard NativeColor(self).getRed(&r, green: &g, blue: &b, alpha: &o) else {
// You can handle the failure here as you want
return (0, 0, 0, 0)
}
return (r, g, b, o)
}
}
Color.red.components.red // 0.9999999403953552 // <- SwiftUI Colors are not pure!
答案 1 :(得分：1)
答案是否-还没有API这样做，但是...
大多数SwiftUI结构的字段都为private，例如Color中的字段。
您可以使用Mirror提取此类信息-但请记住，这样做效率不高。
这里是出于教育目的提取SwiftUI Color的十六进制表示的方法。
将其复制并粘贴到 Xcode 11 游乐场。
import UIKit
import SwiftUI
let systemColor = Color.red
let color = Color(red: 0.3, green: 0.5, blue: 1)
extension Color {
var hexRepresentation: String? {
let children = Mirror(reflecting: color).children
let _provider = children.filter { $0.label == "provider" }.first
guard let provider = _provider?.value else {
return nil
}
let providerChildren = Mirror(reflecting: provider).children
let _base = providerChildren.filter { $0.label == "base" }.first
guard let base = _base?.value else {
return nil
}
var baseValue: String = ""
dump(base, to: &baseValue)
guard let firstLine = baseValue.split(separator: "\n").first,
let hexString = firstLine.split(separator: " ")[1] as Substring? else {
return nil
}
return hexString.trimmingCharacters(in: .newlines)
}
}
systemColor.hexRepresentation
color.hexRepresentation
.red时，.white，dumped等颜色似乎没有太多信息。
只是他们的“系统”名称。
▿ red
▿ provider: SwiftUI.(unknown context at $1297483bc).ColorBox<SwiftUI.SystemColorType> #0
- super: SwiftUI.(unknown context at $129748300).AnyColorBox
- base: SwiftUI.SystemColorType.red
使用Color / red / blue组件实例化的green代替了。
▿ #4C80FFFF
▿ provider: SwiftUI.(unknown context at $11cd2e3bc).ColorBox<SwiftUI.Color._Resolved> #0
- super: SwiftUI.(unknown context at $11cd2e300).AnyColorBox
▿ base: #4C80FFFF
- linearRed: 0.073238954
- linearGreen: 0.21404114
- linearBlue: 1.0
- opacity: 1.0
在操场上，您将看到：
systemColor.hexRepresentation返回nil color.hexRepresentation返回"#4C80FFFF" 答案 2 :(得分：1)
根据@Mojtaba 的回答，我想出了一个更短、更灵活的版本：
#if canImport(UIKit)
import UIKit
#elseif canImport(AppKit)
import AppKit
#endif
extension Color {
#if canImport(UIKit)
var asNative: UIColor { UIColor(self) }
#elseif canImport(AppKit)
var asNative: NSColor { NSColor(self) }
#endif
var rgba: (red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) {
let color = asNative.usingColorSpace(.deviceRGB)!
var t = (CGFloat(), CGFloat(), CGFloat(), CGFloat())
color.getRed(&t.0, green: &t.1, blue: &t.2, alpha: &t.3)
return t
}
var hsva: (hue: CGFloat, saturation: CGFloat, value: CGFloat, alpha: CGFloat) {
let color = asNative.usingColorSpace(.deviceRGB)!
var t = (CGFloat(), CGFloat(), CGFloat(), CGFloat())
color.getHue(&t.0, saturation: &t.1, brightness: &t.2, alpha: &t.3)
return t
}
}
做 asNative.redComponent 等也可能有用，仅供参考。
答案 3 :(得分：0)
等待API我已经在简单的rgba情况下滥用了CustomStringConvertible协议，其中颜色描述格式为#rrggbbaa
debugPrint(Color.red)
debugPrint(Color(red: 1.0, green: 0.0, blue: 0.0))
debugPrint(Color(red: 1.0, green: 0.3, blue: 0.0))
debugPrint(Color(.sRGB, red: 1.0, green: 0.0, blue: 0.5, opacity: 0.3))
debugPrint(Color(hue: 1.0, saturation: 0.0, brightness: 1.0))
debugPrint(Color(.displayP3, red: 1.0, green: 0.0, blue: 0.0, opacity: 1.0).description)
red
#FF0000FF
#FF4C00FF
#FF00804D
#FFFFFFFF
"DisplayP3(red: 1.0, green: 0.0, blue: 0.0, opacity: 1.0)"
如您所见，诸如Color.red之类的东西只会转储“ red”，但是如果您正在使用 由代码（即从颜色选择器）生成的简单RGB颜色，那么还算不错
extension SwiftUI.Color {
var redComponent: Double? {
let val = description
guard description.hasPrefix("#") else { return nil }
let r1 = val.index(val.startIndex, offsetBy: 1)
let r2 = val.index(val.startIndex, offsetBy: 2)
return Double(Int(val[r1...r2], radix: 16)!) / 255.0
}
var greenComponent: Double? {
let val = description
guard description.hasPrefix("#") else { return nil }
let g1 = val.index(val.startIndex, offsetBy: 3)
let g2 = val.index(val.startIndex, offsetBy: 4)
return Double(Int(val[g1...g2], radix: 16)!) / 255.0
}
var blueComponent: Double? {
let val = description
guard description.hasPrefix("#") else { return nil }
let b1 = val.index(val.startIndex, offsetBy: 5)
let b2 = val.index(val.startIndex, offsetBy: 6)
return Double(Int(val[b1...b2], radix: 16)!) / 255.0
}
var opacityComponent: Double? {
let val = description
guard description.hasPrefix("#") else { return nil }
let b1 = val.index(val.startIndex, offsetBy: 7)
let b2 = val.index(val.startIndex, offsetBy: 8)
return Double(Int(val[b1...b2], radix: 16)!) / 255.0
}
}
答案 4 :(得分：0)
您可以使用UIColor并将UIColor转换为Color。 代码：
extension UIColor {
func hexValue() -> String {
let values = self.cgColor.components
var outputR: Int = 0
var outputG: Int = 0
var outputB: Int = 0
var outputA: Int = 1
switch values!.count {
case 1:
outputR = Int(values![0] * 255)
outputG = Int(values![0] * 255)
outputB = Int(values![0] * 255)
outputA = 1
case 2:
outputR = Int(values![0] * 255)
outputG = Int(values![0] * 255)
outputB = Int(values![0] * 255)
outputA = Int(values![1] * 255)
case 3:
outputR = Int(values![0] * 255)
outputG = Int(values![1] * 255)
outputB = Int(values![2] * 255)
outputA = 1
case 4:
outputR = Int(values![0] * 255)
outputG = Int(values![1] * 255)
outputB = Int(values![2] * 255)
outputA = Int(values![3] * 255)
default:
break
}
return "#" + String(format:"%02X", outputR) + String(format:"%02X", outputG) + String(format:"%02X", outputB) + String(format:"%02X", outputA)
}
}
答案 5 :(得分：0)
我发现@Mojtaba Hosseinis的答案很好用，除非您在资产中声明颜色带有明暗外观。
然后我发现使用UIColor(self)时，深色外观以某种方式消失了。这是我想出的解决方法：
请注意，这仅适用于iOS，因为我的应用程序仅为iOS，您当然可以与@Mojtaba Hosseini进行相同的操作，并将其也适应macOS。
extension Color {
var components: (r: Double, g: Double, b: Double, o: Double)? {
let uiColor: UIColor
var r: CGFloat = 0
var g: CGFloat = 0
var b: CGFloat = 0
var o: CGFloat = 0
if self.description.contains("NamedColor") {
let lowerBound = self.description.range(of: "name: \"")!.upperBound
let upperBound = self.description.range(of: "\", bundle")!.lowerBound
let assetsName = String(self.description[lowerBound..<upperBound])
uiColor = UIColor(named: assetsName)!
} else {
uiColor = UIColor(self)
}
guard uiColor.getRed(&r, green: &g, blue: &b, alpha: &o) else { return nil }
return (Double(r), Double(g), Double(b), Double(o))
}
}
这个想法是改用UIColor(named:)初始化程序，在所有外观正确的地方。
幸运的是，我们在资产中设置的名称保存在Color的描述中。我们只需要抽象它，因为还有其他信息，即捆绑等。
答案 6 :(得分：0)
简单的单线：
print(UIColor(Color.blue).cgColor.components)
你得到一个 [CGFloat]? 的 [red, green, blue, alpha]。