布尔属性无法快速标记为动态 [英] Bool Property Cannot be marked dynamic in swift

问题描述

我正在尝试使用KVO快速观察Bool值，并添加这样的dynamic修饰符:

I'm trying to observe Bool value in swift using KVO and add dynamic modifier like this :

dynamic var isRestricted:Bool?

和编译器说

无法将属性标记为动态，因为其类型不能为 代表在Objective-C

Property cannot be marked dynamic because its type canot be represented in Objective-C

那我该怎么办?我应该为此更改为NSNumber吗?那么观察价值的最佳实践是什么?

then what should I do? should I change to NSNumber for this? and What is the best practice for observing value then?

我使用xcode 7 beta 2

im using xcode 7 beta 2

推荐答案

实际问题是无法表示 optional 布尔值 在Objective-C中(因此未标记为动态).使用非可选

The actual problem is that optional booleans cannot be represented in Objective-C (and therefore not marked dynamic). Using a non-optional

dynamic var isRestricted : Bool = false

应该解决问题.

通常，Objective-C中不存在可选"的概念， 但是对NSObject子类实例的可选引用是 在Objective-C中桥接到可为空的对象指针，所以

Generally, the concept of "optionals" does not exist in Objective-C, but optional references to instances of NSObject subclasses are bridged to nullable object pointers in Objective-C, so

dynamic var foo: Foo?

仅当Foo是NSObject的子类时，才允许

.

is allowed if (and only) if Foo is a subclass of NSObject.

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