如何在Swift中指示for循环的键是NSString？ [英] How can I indicate in a Swift that key of for loop is NSString?

问题描述

这里我有一个for循环。我知道我存储NSStrings在它。如何指示 attributeName 的类型？我不想写循环中的任何地方，（relationshipName as NSString）。

 code> 

UPDATE

如果我添加 [String] 和for循环声明，我得到以下错误： p>

>

UPDATE

as String也有问题

解决方案

您必须将 attributesByName 返回的字典转换为实际键/值类型：

  let attributes = managedObject.entity.attributesByName as [String：NSAttributeDescription] 
 attribute.keys中的attributeName {
 // attributeName的类型为String 
 // ... 
} 
  

或

  let attributes = managedObject.entity.attributesByName as [NSString：NSAttributeDescription] 
 for attributeName in attributes.keys { 
 // attributeName的类型为NSString 
 // ... 
} 
  

Here I have a for loop. I know that I store NSStrings in it. How can I indicate the type of attributeName? I do not want to write everywhere inside the loop, that (relationshipName as NSString).

for attributeName in managedObject.entity.attributesByName.keys {
}

UPDATE

If I add [String] and of the for loop declaration, I get the following error:

UPDATE

as String has also problem

解决方案

You have to cast the dictionary returned by attributesByName to the real key/value type:

let attributes = managedObject.entity.attributesByName as [String: NSAttributeDescription]
for attributeName in attributes.keys  {
    // attributeName has the type String
    // ...
}

or

let attributes = managedObject.entity.attributesByName as [NSString: NSAttributeDescription]
for attributeName in attributes.keys  {
    // attributeName has the type NSString
    // ...
}

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