如何在代码中使用两个大小类创建UITraitCollection？

Question

我有mysql.*的简单扩展名：

UITraitCollection

之前，我需要为此编写测试（使用TDD）：

extension UITraitCollection {

    var isIpad: Bool {
        return horizontalSizeClass == .Regular && verticalSizeClass == .Regular
    }
}

但错误是：

  

无法分配给属性：let traitCollection = UITraitCollection(verticalSizeClass: .Regular) //the init is either for vertical or horizontal at time traitCollection.horizontalSizeClass = .Regular //error XCTAssertTrue(traitCollection.isIpad) 是一个只获得属性。

那我该怎么办？

Answer 1

好的，我找到了解决方案：

let compactTraitCollection = UITraitCollection(traitsFromCollections: [UITraitCollection(verticalSizeClass: .Compact), UITraitCollection(horizontalSizeClass: .Compact)])
XCTAssertFalse(compactTraitCollection.isIpad)

let regularTraitCollection = UITraitCollection(traitsFromCollections: [UITraitCollection(verticalSizeClass: .Regular), UITraitCollection(horizontalSizeClass: .Regular)])
XCTAssertTrue(regularTraitCollection.isIpad)