A.Roe A.Roe - 11 months ago 628
iOS Question

Working with NSNumber & Integer values in Swift 3

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


Cannot assign type int to type NSNumber


//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

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

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

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

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

&& the second error I get is

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

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

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

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

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


Answer Source

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.

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

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.