断言当前后备特征集包含一个或多个未指定特征：

Question

一旦我们的应用程序在iOS13上运行，则日志中将充满断言。有人提示如何删除它吗？

2019-09-19 08:05:43.528382+0200 Ts-2-cz-test[56066:20590106] [Assert] Current fallback trait collection contains one or more unspecified traits: {(
    "_UITraitNameDisplayScale",
    "_UITraitNameDisplayCornerRadius",
    "_UITraitNameSemanticContext",
    "_UITraitNameUserInterfaceLevel",
    "_UITraitNamePresentationSemanticContext",
    "_UITraitNameVibrancy",
    "_UITraitNameDisplayGamut",
    "_UITraitNameDebugHighlight",
    "_UITraitNamePreferredContentSizeCategory",
    "_UITraitNameTouchLevel",
    "_UITraitNameAccessibilityContrast",
    "_UITraitNameLegibilityWeight"
)}; traitCollection: <UITraitCollection: 0x7fb4ce32ad20; HorizontalSizeClass = Compact>; currentFallbackEnvironment: <UIView: 0x7fb46c421d80; frame = (0 0; 1024 1366); autoresize = W+H; layer = <CALayer: 0x7fb46c421ef0>>

Answer 1

我在这里遇到了同样的问题，因为我覆盖了该traiCollection属性（Apple不建议这样做，但我没有找到其他解决方案），并且我返回的新traitCollection具有许多未指定的特征（如错误消息所述）。

所以现在我返回一个新traitCollection对象，但是我通过添加来初始化它super.traitCollection。因此，在我的视图控制器中，我有类似以下内容：

public override var traitCollection: UITraitCollection {
    var newTraitCollection: [UITraitCollection] = [super.traitCollection]
    // I need to force size class on iPad
    if UIDevice.current.userInterfaceIdiom == .pad {
        newTraitCollection += [UITraitCollection(verticalSizeClass: .regular), UITraitCollection(horizontalSizeClass: .compact)]
    }
    return UITraitCollection(traitsFrom: newTraitCollection)
}