Swift 3错误：[_SwiftValue pointSize]无法识别的选择器发送到实例 [英] Swift 3 error: [_SwiftValue pointSize] unrecognized selector sent to instance

问题描述

我刚刚将项目迁移到swift 3并因为一个问题看到了很多崩溃：

I just migrated our project to swift 3 and see lots of crashes because of one issue:

由于未捕获的异常'NSInvalidArgumentException'而终止应用程序，原因：' - [_ SwiftValue pointSize]：无法识别的选择器发送到实例

该错误的原因是调用：

[NSAttributedString(NSExtendedStringDrawing) boundingRectWithSize:options:context:]

我注意到的是，如果我将String转换为NSString并在其上调用 boundingRectWithSize ，则会抛出该错误。它似乎也发生在许多其他部分，例如，如果我在故事板中发送了一个视图控制器标题，它会抛出相同的错误。

What I noticed is that if I cast String to NSString and call boundingRectWithSize on it it will throw that error. It also seems to be happening in many other parts, for example if I sent a view controller title in a storyboard it throws the same error.

任何人都遇到同样的问题？

Anyone having the same problems?

重现问题：

在Xcode中创建一个新的Swift 3项目8并在viewDidLoad中添加以下行：

Create a new Swift 3 project in Xcode 8 and add the following line in viewDidLoad:

let attributes: [String: AnyObject?] = [
            NSFontAttributeName: UIFont.systemFont(ofSize: 14)
        ]
    let boundingRect = ("hello" as NSString).boundingRect(with: CGSize(width: 100, height: 100), options: .usesLineFragmentOrigin, attributes: attributes, context: nil)

但正如我所说，它在其他许多地方崩溃，因为看起来UIKit在许多部分内部使用此方法

But as I said it crashes in many other places as it seems that UIKit uses this method internally in many parts

推荐答案

如果我使用您的测试代码，但让数据类型 attributes 默认情况下，它不会崩溃。那就是：

If I use your test code, but let the data type of attributes default, it doesn't crash. That is:

let attributes = [NSFontAttributeName: UIFont.systemFont(ofSize: 14)]

按住Option键点击该变量表示它是 [String：UIFont] 。

Option-clicking on the variable says it's [String : UIFont].

进行一些额外测试，表明它与可选对象有关; [String：AnyObject] 似乎工作正常。

A little extra testing, suggests that it's related to the optional object; [String: AnyObject] appears to work OK.

编辑：
毕竟，我决定阅读文档，其中说使用 [String：Any] 。 ：）

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