类型 'CAGradientLayerType'（又名 'NSString'）没有成员 'conic'

Question

我正在尝试使用新的 conic gradient type。我已将部署目标设置为 12.0 并添加了 QuartzCore 框架，并将渐变类型设置为 .conic:

    let gradient = CAGradientLayer()
    gradient.type = CAGradientLayerType.conic

我什至可以点击进入文档：

extension CAGradientLayerType {
    ...

    /* Conic gradient. The gradient is centered at 'startPoint' and its 0-degrees
     * direction is defined by a vector spanned between 'startPoint' and
     * 'endPoint'. When 'startPoint' and 'endPoint' overlap the results are
     * undefined. The gradient's angle increases in the direction of rotation of
     * positive x-axis towards positive y-axis. */

    @available(iOS 12.0, *)
    public static let conic: CAGradientLayerType
}

但我仍然遇到此构建错误：

Type 'CAGradientLayerType' (aka 'NSString') has no member 'conic'

Answer 1

感谢 看来问题是我的 swift 语言版本（目标 > 构建设置 > Swift 语言版本）。它需要是版本 5 才能使用此语法。否则，我想我们需要将 属性 视为字符串，并将其设置为 kCAGradientLayerConic.