Question

下面的代码无法成功编译。我还附上了截图以供参考！

map(lambda x: (x[0], x[1]), cornerWithEdges)

screenshot for reference

Answer 1

您可以使用

进行测试

Map

或

if viewInArray.isKind(of: MyClass) { ... }

但是我认为您不能将Swift转换为在编译时不可用的类。无论如何，您将无法直接调用其任何方法。您可以将其强制转换为某个if viewInArray.isMember(of: MyClass) { ... } // strict class match子类，然后向其发送任意（未在编译时定义）消息。

Answer 2

此处的主要错误是您无法as或is检查动态类型。您需要具有在编译时已知的静态类型才能使用它。如要说明的那样，您需要在基础NSObject上使用isKind(of:)或isMember(of:)。我建议这样做的方法如下：

func firstXibViewOfClass(named classNameString: String) -> NSView? {
    // Create an AnyClass object
    guard let projectName = Bundle.main.infoDictionary?["CFBundleExecutable"] as? String,
        let myClass = NSClassFromString(projectName + "." + classNameString)
        else {
            return nil
    }

    // Load the nib
    var topLevelObjects: NSArray?
    Bundle.main.loadNibNamed(classNameString, owner: nil, topLevelObjects: &topLevelObjects)

    // Convert it to NSObjects (since they all are going to be)
    guard let nsObjectArray = topLevelObjects as? [NSObject] else { return nil }

    // Find the first matching view and return it as an NSView if possible
    return nsObjectArray.first(where: {
        $0.isKind(of: myClass)  // Or isMember(of:) if you want to be strict
    }) as? NSView
}

但是，如果不需要包含子类，则可能只想直接检查类名。这摆脱了所有AnyClass的东西：

func firstXibViewOfClass(named classNameString: String) -> NSView? {
    // Load the nib
    var topLevelObjects: NSArray?
    Bundle.main.loadNibNamed(classNameString, owner: nil, topLevelObjects: &topLevelObjects)

    // Convert it to NSObjects (since they all are going to be)
    guard let nsObjectArray = topLevelObjects as? [NSObject] else { return nil }

    // Find the first matching view and return it as an NSView if possible
    return nsObjectArray.first(where: { $0.className == classNameString }) as? NSView
}

您当然可以只返回AnyObject?，但是方法的名称表明您希望它是一个视图，因此应强制执行该方法或重命名该方法。

如何在Swift中成功编译NSClassFromString

2 个答案: