使用NSNumber& Swift 3中的整数值 [英] Working with NSNumber & Integer values in Swift 3

问题描述

我正在尝试将我的项目转换为Swift 3.0，但是当使用 NSNumber 和整数。

I am trying to convert my project to Swift 3.0 however I am having two error messages when working with NSNumber and Integers.

无法将类型int指定为类型NSNumber

Cannot assign type int to type NSNumber

for

//item is a NSManaged object with a property called index of type NSNumber 

var currentIndex = 0
 for item in self.selectedObject.arrayOfItems {
   item.index = currentIndex
   currentIndex += 1
 }

即使我将 currentIndex 更改为类型 NSNumber 然后我收到错误

and even when I change currentIndex to a type NSNumber then I get the error

二进制运算符'+ ='不能应用于'NSNumber'和'Int'

Binary operator '+=' cannot be applied to type 'NSNumber' and 'Int'

然后我创建一个名为的属性类型 NSNumber 添加到 currentIndex 但是然后得到以下错误;

so then I create a property called one of type NSNumber to add to currentIndex but then get the following error;

二元运算符'+ ='不能应用于两个NSNumber操作数

Binary operator '+=' cannot be applied to two NSNumber operands

&&我得到的第二个错误是

&& the second error I get is

没有'+'候选人产生预期的上下文结果类型NSNumber

No '+' candidates produce the expected contextual result type NSNumber

 let num: Int = 210
 let num2: Int = item.points.intValue
 item.points = num + num2

这里我只是尝试将210添加到points属性值 item 是一个 NSManagedObject 。

Here I am just trying to add 210 to the points property value, item is a NSManagedObject.

所以基本上我在向 NSNumber 类型的属性添加数字时遇到了问题。我正在使用 NSNumber ，因为它们是 NSManagedObject 的属性。

So basically I am having issues getting my head around adding numbers to properties of type NSNumber. I am working with NSNumber because they are properties of NSManagedObject's.

任何人都可以帮助我吗？我有80多个错误，这些错误都是上面提到的错误之一。

Can anyone help me out ? I have over 80 errors which are all either one of the above errors mentioned.

谢谢

推荐答案

在Swift 3之前，很多类型都是自动在必要时桥接到某个 NSObject 子类的
实例，例如 String 到
NSString ，或 Int ， Float ，...到 NSNumber 。

Before Swift 3, many types were automatically "bridged" to an instance of some NSObject subclass where necessary, such as String to NSString, or Int, Float, ... to NSNumber.

从Swift 3开始，您必须明确转换：

As of Swift 3 you have to make that conversion explicit:

var currentIndex = 0
for item in self.selectedFolder.arrayOfTasks {
   item.index = currentIndex as NSNumber // <--
   currentIndex += 1
}

或者，使用选项使用标量原始数据类型的属性在创建 NSManagedObject 子类时，
然后该属性有一些整数类型而不是 NSNumber ，
这样你就可以在不转换的情况下获得并设置它。

Alternatively, use the option "Use scalar properties for primitive data types" when creating the NSManagedObject subclass, then the property has some integer type instead of NSNumber, so that you can get and set it without conversion.

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