supportedInterfaceOrientations方法不会覆盖其超类中的任何方法 [英] The supportedInterfaceOrientations method doesn't override any method from its superclass

问题描述

在UIViewController中，此代码：

In a UIViewController, this code:

public override func supportedInterfaceOrientations() -> UIInterfaceOrientationMask {
    if let mainController = self.mainViewController{
        return mainController.supportedInterfaceOrientations
    }
    return UIInterfaceOrientationMask.all
}

给出错误方法不会覆盖其超类中的任何方法

我使用的是Xcode 8 beta 4，iOS部署目标是9.0，而使用Legacy Swift语言版本设置为No 构建设置

I am using Xcode 8 beta 4 and the iOS deployment target is 9.0, and Use Legacy Swift Language Version is set to No in the Build Settings

我如何将上面的代码转换为Swift 3？

How could I convert the code above to Swift 3?

推荐答案

像这样：

override var supportedInterfaceOrientations : UIInterfaceOrientationMask {

...其余的就像你拥有它一样。

...and the rest as you have it.

现在很多Cocoa方法都是属性，所以你将它们实现为覆盖计算变量。因此从种子3（或更早）移动到种子4的模式是：

A lot of Cocoa methods are properties now, so you implement them as override computed variables. So the pattern for moving from seed 3 (or earlier) to seed 4 is:

• 更改 func 到 var

删除（）

将 - > 更改为：

这是因为计算变量有一个getter函数，所以你正在实现的函数在简单地变成getter函数之前。这些是只读属性，因此您不需要设置器。

This works because a computed variable has a getter function, so the function you were implementing before simply turns into the getter function. And these are read-only properties, so you won't need a setter.

同样受影响的方法是 preferredStatusBarStyle ， prefersStatusBarHidden ， shouldAutorotate ， preferredInterfaceOrientationForPresentation 等等。在Objective-C标题中查找 UIKIT_DEFINE_AS_PROPERTIES 。

Similarly affected methods are preferredStatusBarStyle, prefersStatusBarHidden, shouldAutorotate, preferredInterfaceOrientationForPresentation, and many others. Look for UIKIT_DEFINE_AS_PROPERTIES in the Objective-C header.

从长远来看，您可以进行其他更改。例如，您可以添加一个setter（将您的实现划分为 get 和 set 函数），因此您可以将您的实现转换为存储属性的外观。例如：

In the longer term, there are other changes you can make. For example, you can add a setter (dividing your implementation into get and set functions), and thus you can turn your implementation into a facade for a stored property. For example:

private var _orientations = UIInterfaceOrientationMask.portrait
override var supportedInterfaceOrientations : UIInterfaceOrientationMask {
    get { return self._orientations }
    set { self._orientations = newValue }
}

所以现在你的代码有办法设置这个值。如果你在不同的时间返回不同的值，这可能会使事情更加清晰。

So now your code has a way to set this value. If you were returning different values at different times, this could make things a lot cleaner.

有趣的是，这种变化对现有的Objective-C代码没有直接影响，因为在Objective-C中，新的属性声明， @property（非原子，只读）UIInterfaceOrientationMask supportedInterfaceOrientations; ，通过与以前相同的方法得到满足：

Interestingly, this change has no direct effect on existing Objective-C code, because in Objective-C, the new property declaration, @property(nonatomic, readonly) UIInterfaceOrientationMask supportedInterfaceOrientations;, is satisfied by the same method as before:

- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    return UIInterfaceOrientationMaskPortrait;
}

原因是在Objective-C中， @property（readonly）只是一个相应的getter方法存在的承诺，而这正是这个方法的意义所在。但是在Swift中，编写Objective-C属性的getter方法的方法是通过属性，即通过实例变量。因此，只有Swift代码会受到更改的影响：您必须将方法重写为属性。

The reason is that in Objective-C, a @property(readonly) is merely a promise that a corresponding getter method exists, and that's exactly what this method is. But in Swift, the way to write an Objective-C property's getter method is through a property, that is, through an instance variable. So only Swift code is affected by the change: you have to rewrite your methods as properties.

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