如何在目标c中使用具有泛型类型的Swift类 [英] How to use a swift class with a generic type in objective c

问题描述

我有一个NumericType T的swift类。

  @objc class MathStatistics< T：NumericType> ：NSObject {
 var numbers = [T]（）
 
 func sum（） - > T' {
 if numbers.count == 0 {
 return nil 
} 
 
 var sum = T（0）
 
数字{
 sum = sum + value 
} 
返回金额
} 
} 
  

在swift中，初始化类对象如下：

  let statistics = MathStatistics< Double>（）
  

如何在Objective C中初始化同一个对象？
以下行不设置数字类型T。

  MathStatistics * stats = [[MathStatistics alloc] init] ; 
  

解决方案

你不能。如文档：

您可以访问类别或协议中的任何内容，即
用@objc属性标记，只要它与
Objective-C兼容即可。这不包括Swift-only特性，例如这里列出的
：
$ b

• 泛型


• 元组
  
• 在Swift中定义的枚举


• 在Swift中定义的结构


• 在Swift中定义的顶级函数


• Swift中定义的全局变量
  
• Swift中定义的类型别
  
• Swift风格的变量


• 嵌套类型
  
• 咖喱函数
  
  

<你必须摆脱你班级的泛型。然后你可以在Objective-C
中使用它

I have the following swift class with a NumericType T.

@objc class MathStatistics<T: NumericType> : NSObject {
        var numbers = [T]()

        func sum() -> T? {
            if numbers.count == 0 {
                return nil
            }

            var sum = T(0)

            for value in numbers {
                sum = sum + value
            }
            return sum
        }
    }

In swift a initialize the class object as follows:

let statistics = MathStatistics<Double>()

How do I initialize the same object in Objective C? The following line does not set the numeric type T.

MathStatistics *stats = [[MathStatistics alloc] init];

解决方案

You can't. As listed in the documentation:

You’ll have access to anything within a class or protocol that’s marked with the @objc attribute as long as it’s compatible with Objective-C. This excludes Swift-only features such as those listed here:

• Generics
• Tuples
• Enumerations defined in Swift
• Structures defined in Swift
• Top-level functions defined in Swift
• Global variables defined in Swift
• Typealiases defined in Swift
• Swift-style variadics
• Nested types
• Curried functions

You'd have to get rid of generics in your class. Then you can use it in Objective-C

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