Color的init(_:white:opacity:)方法的误解

第一次看到这个方法的时候是我在学习scaledToFit这个方法的时候，apple有一个官方代码是这样的：

Circle()
    .fill(Color.pink)
    .scaledToFit()
    .frame(width: 300, height: 150)
    .border(Color(white: 0.75))

我们可以看到在粉色的圆形之外，添加了一个0.75灰阶的矩形边框。这里的外框就是通过代码 .border(Color（white:0.75))来实现的 Color（white:0.75)我一开始以为是创建一个白色的透明度为0.75的颜色，其实不是。这里真正的效果是创建一个 0.75灰阶的颜色，如果white取0就是黑色，取1就是白色。

在Apple中的定义

init(_:white:opacity:)

init(
    _ colorSpace: Color.RGBColorSpace = .sRGB,
    white: Double,
    opacity: Double = 1
)

    /// Creates a constant grayscale color.
    ///
    /// This initializer creates a constant color that doesn't change based
    /// on context. For example, it doesn't have distinct light and dark
    /// appearances, unlike various system-defined colors, or a color that
    /// you load from an Asset Catalog with ``init(_:bundle:)``.
    ///
    /// A standard sRGB color space clamps the `white` component
    /// to a range of `0` to `1`, but SwiftUI colors
    /// use an extended sRGB color space, so
    /// you can use component values outside that range. This makes it
    /// possible to create colors using the ``RGBColorSpace/sRGB`` or
    /// ``RGBColorSpace/sRGBLinear`` color space that make full use of the wider
    /// gamut of a diplay that supports ``RGBColorSpace/displayP3``.
    ///
    /// - Parameters:
    ///   - colorSpace: The profile that specifies how to interpret the color
    ///     for display. The default is ``RGBColorSpace/sRGB``.
    ///   - white: A value that indicates how white
    ///     the color is, with higher values closer to 100% white, and lower
    ///     values closer to 100% black.
    ///   - opacity: An optional degree of opacity, given in the range `0` to
    ///     `1`. A value of `0` means 100% transparency, while a value of `1`
    ///     means 100% opacity. The default is `1`.
    public init(_ colorSpace: Color.RGBColorSpace = .sRGB, white: Double, opacity: Double = 1)