如何在swift中将Int转换为int？

Question

I have a variable called number of type Int

var number = value!.integerValue as Int

Now I have to create a NSNumber object using that value.

I am trying to use this constructor

value = NSNumber(int: number)

, but it does not work.

It expect the primitive type int, not Int I guess.

Anyone know how to get around this?

Thanks!

Answer 1

You just do value = number

As you can see in the documentation:

https://developer.apple.com/library/ios/documentation/Swift/Conceptual/BuildingCocoaApps/WorkingWithCocoaDataTypes.html

the native swift number types generally bridge directly to NSNumber .

Numbers

Swift automatically bridges certain native number types, such as Int and Float, to NSNumber. This bridging lets you create an NSNumber from one of these types:

SWIFT

let n = 42
let m: NSNumber = n
It also allows you to pass a value of type Int, for example, to an argument expecting an NSNumber. Note that because NSNumber can contain a variety of different types, you cannot pass it to something expecting an Int value.

All of the following types are automatically bridged to NSNumber:

Int
UInt
Float
Double
Bool

Swift 3 update

In Swift 3, this bridging conversion is no longer automatic and you have to cast it explicitly like this:

let n = 42
let m: NSNumber = n as NSNumber

Answer 2

The issue is because in ObjC, an int is a 32 bit number, and an integer or NSInteger is a 64 bit number.

var number = value!.integerValue as Int

Number is of type Int which corresponds to the ObjC type NSInteger

You now try to create with this:

value = NSNumber(int: number)

Which takes an Int32 or int type, thus resulting in failure. You have a few options that will work.

One:

value = NSNumber(int: Int32(number))

Two (probably better):

value = NSNumber(integer: number)

Three (probably best):

As @Dima points out, you can just set it directly because swift automatically converts:

value = number

Answer 3

对于Swift 3，你必须使用：

var convertedNumber = NSNumber(value: numberToConvert)