[英]NSManagedObject and protocol conformance
Here is my problem, I have an type ( MyManObj ) which is a subclass of NSManagedObject
. 这是我的问题,我有一个类型( MyManObj ),它是
NSManagedObject
的子NSManagedObject
。
This type has two fields: fieldOne , fieldTwo : Int16
此类型有两个字段: fieldOne , fieldTwo :
Int16
I also have a protocol defined this way: 我也有这样定义的协议:
@objc protocol MyProtocol {
var fieldOne:Int16 {get set}
var fieldTwo:Int16 {get set}
}
I need to express the fact that MyManObj conforms to MyProtocol . 我需要表达一个事实,即MyManObj符合MyProtocol 。 And I don't know how to do it.
而且我不知道该怎么做。
I have tried to add code like this, but it does not work: 我试图添加这样的代码,但是它不起作用:
extension MyManObj:MyProtocol {}
Precisely I get this message: 恰好我收到此消息:
Type 'MyManObj' does not conform to protocol 'MyProtocol'.
I have then tried a few more variations, but with no interest because they failed. 然后,我尝试了更多的变体,但没有兴趣,因为它们失败了。
You are getting this error because the variables/ properties in your protocol are not marked optional [ie they are required] and your compiler is asking you to implement all the method/ properties declared in your protocol. 之所以出现此错误,是因为协议中的变量/属性未标记为可选(即它们是必需的),并且编译器要求您实现协议中声明的所有方法/属性。
To resolve this issue you can do: 要解决此问题,您可以执行以下操作:
@objc protocol MyProtocol: class {
optional var fieldOne:Int16 {get set}
optional var fieldTwo:Int16 {get set}
}
OR 要么
extension MyManObj:MyProtocol {
var fieldOne:Int16 {
get{}
set{}
}
var fieldTwo:Int16 {
get{}
set{}
}
}
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