调用@Environment时收到错误"Class 'Environment‘不能用作属性“

Question

我尝试在SwiftUI中包含具有自定义字体的动态类型，但当我试图获取环境的sizeCategory时，此错误不断被调用。

我尝试过使用@Environment来获取sizeCategory以外的对象，但它总是抛出相同的错误。

我使用的是Xcode11Beta5上的this StackOverflow帖子中的代码修改版，它似乎适用于其他所有人，所以我真的很困惑为什么它不适用于我。

struct RawlineFont: ViewModifier {
  var textStyle: Font.TextStyle

  @Environment(\.sizeCategory) var sizeCategory : ContentSizeCategory

  init(_ textStyle: Font.TextStyle = .body) {
    self.textStyle = textStyle
  }

  func body(content: Content) -> some View {
    content.font(getFont())
  }

  func getFont() -> Font {
    switch(self.sizeCategory) {
    case .extraSmall:
      return Font.custom("Rawline", size: 16 * getStyleFactor())
    case .small:
      return Font.custom("Rawline", size: 21 * getStyleFactor())
    case .medium:
      return Font.custom("Rawline", size: 24 * getStyleFactor())
    case .large:
      return Font.custom("Rawline", size: 28 * getStyleFactor())
    case .extraLarge:
      return Font.custom("Rawline", size: 32 * getStyleFactor())
    case .extraExtraLarge:
      return Font.custom("Rawline", size: 36 * getStyleFactor())
    case .extraExtraExtraLarge:
      return Font.custom("Rawline", size: 40 * getStyleFactor())
    case .accessibilityMedium:
      return Font.custom("Rawline", size: 48 * getStyleFactor())
    case .accessibilityLarge:
      return Font.custom("Rawline", size: 52 * getStyleFactor())
    case .accessibilityExtraLarge:
      return Font.custom("Rawline", size: 60 * getStyleFactor())
    case .accessibilityExtraExtraLarge:
      return Font.custom("Rawline", size: 66 * getStyleFactor())
    case .accessibilityExtraExtraExtraLarge:
      return Font.custom("Rawline", size: 72 * getStyleFactor())
    @unknown default:
      return Font.custom("Rawline", size: 36 * getStyleFactor())
    }
  }

  func getStyleFactor() -> CGFloat {
    switch textStyle {
    case .caption:
      return 0.6
    case .footnote:
      return 0.7
    case .subheadline:
      return 0.8
    case .callout:
      return 0.9
    case .body:
      return 1.0
    case .headline:
      return 1.2
    case .title:
      return 1.5
    case .largeTitle:
      return 2.0
    @unknown default:
      return 1.0
    }
  }

}

Error message

完整的代码文件：

//
//  Fonts.swift
//  Team Study
//
//  Created by Aditya Chugh on 2019-07-02.
//  Copyright © 2019 Aditya Chugh. All rights reserved.
//

import SwiftUI

class Rawline {

  static let extraLight = "RawlineExtraLight-Regular"
  static let extraLightItalic = "RawlineExtraLight-Italic"

  static let light = "RawlineLight-Regular"
  static let lightItalic = "RawlineLight-Italic"

  static let thin = "RawlineThin-Regular"
  static let thinItalic = "Rawline-ThinItalic"

  static let regular = "Rawline-Regular"
  static let italic = "Rawline-Italic"

  static let medium = "RawlineMedium-Regular"
  static let mediumItalic = "RawlineMedium-Italic"

  static let semiBold = "RawlineSemiBold-Regular"
  static let semiBoldItalic = "RawlineSemiBold-Italic"

  static let bold = "Rawline-Bold"
  static let boldItalic = "Rawline-BoldItalic"

  static let extraBold = "RawlineExtraBold-Regular"
  static let extraBoldItalic = "RawlineExtraBold-Italic"

  static let black = "RawlineBlack-Regular"
  static let blackItalic = "RawlineBlack-Italic"

}

struct RawlineFont: ViewModifier {
  var textStyle: Font.TextStyle

  @Environment(\.sizeCategory) var sizeCategory : ContentSizeCategory

  init(_ textStyle: Font.TextStyle = .body) {
    self.textStyle = textStyle
  }

  func body(content: Content) -> some View {
    content.font(getFont())
  }

  func getFont() -> Font {
    switch(self.sizeCategory) {
    case .extraSmall:
      return Font.custom("Rawline", size: 16 * getStyleFactor())
    case .small:
      return Font.custom("Rawline", size: 21 * getStyleFactor())
    case .medium:
      return Font.custom("Rawline", size: 24 * getStyleFactor())
    case .large:
      return Font.custom("Rawline", size: 28 * getStyleFactor())
    case .extraLarge:
      return Font.custom("Rawline", size: 32 * getStyleFactor())
    case .extraExtraLarge:
      return Font.custom("Rawline", size: 36 * getStyleFactor())
    case .extraExtraExtraLarge:
      return Font.custom("Rawline", size: 40 * getStyleFactor())
    case .accessibilityMedium:
      return Font.custom("Rawline", size: 48 * getStyleFactor())
    case .accessibilityLarge:
      return Font.custom("Rawline", size: 52 * getStyleFactor())
    case .accessibilityExtraLarge:
      return Font.custom("Rawline", size: 60 * getStyleFactor())
    case .accessibilityExtraExtraLarge:
      return Font.custom("Rawline", size: 66 * getStyleFactor())
    case .accessibilityExtraExtraExtraLarge:
      return Font.custom("Rawline", size: 72 * getStyleFactor())
    @unknown default:
      return Font.custom("Rawline", size: 36 * getStyleFactor())
    }
  }

  func getStyleFactor() -> CGFloat {
    switch textStyle {
    case .caption:
      return 0.6
    case .footnote:
      return 0.7
    case .subheadline:
      return 0.8
    case .callout:
      return 0.9
    case .body:
      return 1.0
    case .headline:
      return 1.2
    case .title:
      return 1.5
    case .largeTitle:
      return 2.0
    @unknown default:
      return 1.0
    }
  }

}

Answer 1

我也收到了同样的错误信息。原来我定义了另一个名为Environment的类型，编译器正在拾取该类型。

这对我来说很有效：@SwiftUI.Environment(\.colorScheme) var colorScheme : ColorScheme

希望这能对你有所帮助

Answer 2

如果您的应用程序中有另一个名为Environment的对象，则会与SwiftUI的环境关键字发生冲突。请更改自定义Environment对象的名称

Answer 3

我就是那个回答你提到的问题的人。我刚刚用beta 5测试了你发布的代码，它工作得很好。但是，请注意，使用SwiftUI时，您可能会在某些地方得到错误，而真正的错误在其他地方。我敢打赌，你的代码的其他部分可能有不平衡的括号。也可能是完全不同的东西。再次检查，如果问题仍然存在，请发布您的完整代码。