Is there a way to print the runtime type of a variable in swift? For example:
var now = NSDate()
var soon = now.dateByAddingTimeInterval(5.0)
println("\(now.dynamicType)")
// Prints "(Metatype)"
println("\(now.dynamicType.description()")
// Prints "__NSDate" since objective-c Class objects have a "description" selector
println("\(soon.dynamicType.description()")
// Compile-time error since ImplicitlyUnwrappedOptional<NSDate> has no "description" method
In the example above, I'm looking for a way to show that the variable "soon" is of type ImplicitlyUnwrappedOptional<NSDate>
, or at least NSDate!
.
Update September 2016
Swift 3.0: Use type(of:)
, e.g. type(of: someThing)
(since the dynamicType
keyword has been removed)
Update October 2015:
I updated the examples below to the new Swift 2.0 syntax (e.g. println
was replaced with print
, toString()
is now String()
).
From the Xcode 6.3 release notes:
@nschum points out in the comments that the Xcode 6.3 release notes show another way:
Type values now print as the full demangled type name when used with println or string interpolation.
import Foundation
class PureSwiftClass { }
var myvar0 = NSString() // Objective-C class
var myvar1 = PureSwiftClass()
var myvar2 = 42
var myvar3 = "Hans"
print( "String(myvar0.dynamicType) -> \(myvar0.dynamicType)")
print( "String(myvar1.dynamicType) -> \(myvar1.dynamicType)")
print( "String(myvar2.dynamicType) -> \(myvar2.dynamicType)")
print( "String(myvar3.dynamicType) -> \(myvar3.dynamicType)")
print( "String(Int.self) -> \(Int.self)")
print( "String((Int?).self -> \((Int?).self)")
print( "String(NSString.self) -> \(NSString.self)")
print( "String(Array<String>.self) -> \(Array<String>.self)")
Which outputs:
String(myvar0.dynamicType) -> __NSCFConstantString
String(myvar1.dynamicType) -> PureSwiftClass
String(myvar2.dynamicType) -> Int
String(myvar3.dynamicType) -> String
String(Int.self) -> Int
String((Int?).self -> Optional<Int>
String(NSString.self) -> NSString
String(Array<String>.self) -> Array<String>
Update for Xcode 6.3:
You can use the _stdlib_getDemangledTypeName()
:
print( "TypeName0 = \(_stdlib_getDemangledTypeName(myvar0))")
print( "TypeName1 = \(_stdlib_getDemangledTypeName(myvar1))")
print( "TypeName2 = \(_stdlib_getDemangledTypeName(myvar2))")
print( "TypeName3 = \(_stdlib_getDemangledTypeName(myvar3))")
and get this as output:
TypeName0 = NSString
TypeName1 = __lldb_expr_26.PureSwiftClass
TypeName2 = Swift.Int
TypeName3 = Swift.String
Original answer:
Prior to Xcode 6.3 _stdlib_getTypeName
got the mangled type name of a variable. Ewan Swick's blog entry helps to decipher these strings:
e.g. _TtSi
stands for Swift's internal Int
type.
Mike Ash has a great blog entry covering the same topic.
Edit: A new toString
function has been introduced in Swift 1.2 (Xcode 6.3).
You can now print the demangled type of any type using .self
and any instance using .dynamicType
:
struct Box<T> {}
toString("foo".dynamicType) // Swift.String
toString([1, 23, 456].dynamicType) // Swift.Array<Swift.Int>
toString((7 as NSNumber).dynamicType) // __NSCFNumber
toString((Bool?).self) // Swift.Optional<Swift.Bool>
toString(Box<SinkOf<Character>>.self) // __lldb_expr_1.Box<Swift.SinkOf<Swift.Character>>
toString(NSStream.self) // NSStream
Try calling YourClass.self
and yourObject.dynamicType
.
Reference: https://devforums.apple.com/thread/227425.
someInstance.dynamicType.printClassName()
will print the name of the class.
Swift 3.0
let string = "Hello"
let stringArray = ["one", "two"]
let dictionary = ["key": 2]
print(type(of: string)) // "String"
// Get type name as a string
String(describing: type(of: string)) // "String"
String(describing: type(of: stringArray)) // "Array<String>"
String(describing: type(of: dictionary)) // "Dictionary<String, Int>"
// Get full type as a string
String(reflecting: type(of: string)) // "Swift.String"
String(reflecting: type(of: stringArray)) // "Swift.Array<Swift.String>"
String(reflecting: type(of: dictionary)) // "Swift.Dictionary<Swift.String, Swift.Int>"
Is this what you're looking for?
println("\(object_getClassName(now))");
It prints "__NSDate"
UPDATE: Please note this no longer seems to work as of Beta05
My current Xcode is Version 6.0 (6A280e).
import Foundation
class Person { var name: String; init(name: String) { self.name = name }}
class Patient: Person {}
class Doctor: Person {}
var variables:[Any] = [
5,
7.5,
true,
"maple",
Person(name:"Sarah"),
Patient(name:"Pat"),
Doctor(name:"Sandy")
]
for variable in variables {
let typeLongName = _stdlib_getDemangledTypeName(variable)
let tokens = split(typeLongName, { $0 == "." })
if let typeName = tokens.last {
println("Variable \(variable) is of Type \(typeName).")
}
}
Output:
Variable 5 is of Type Int.
Variable 7.5 is of Type Double.
Variable true is of Type Bool.
Variable maple is of Type String.
Variable Swift001.Person is of Type Person.
Variable Swift001.Patient is of Type Patient.
Variable Swift001.Doctor is of Type Doctor.
Optional(...)
, so your code would only return Optional
as the Type. It should also show var optionalTestVar: Person? = Person(name:"Sarah")
as Optional(Person) and var with Person! as ImplicitlyUnwrappedOptional(Person)
As of Xcode 6.3 with Swift 1.2, you can simply convert type values into the full demangled String
.
toString(Int) // "Swift.Int"
toString(Int.Type) // "Swift.Int.Type"
toString((10).dynamicType) // "Swift.Int"
println(Bool.self) // "Swift.Bool"
println([UTF8].self) // "Swift.Array<Swift.UTF8>"
println((Int, String).self) // "(Swift.Int, Swift.String)"
println((String?()).dynamicType)// "Swift.Optional<Swift.String>"
println(NSDate) // "NSDate"
println(NSDate.Type) // "NSDate.Type"
println(WKWebView) // "WKWebView"
toString(MyClass) // "[Module Name].MyClass"
toString(MyClass().dynamicType) // "[Module Name].MyClass"
You can still access the class, through className
(which returns a String
).
There are actually several ways to get the class, for example classForArchiver
, classForCoder
, classForKeyedArchiver
(all return AnyClass!
).
You can't get the type of a primitive (a primitive is not a class).
Example:
var ivar = [:]
ivar.className // __NSDictionaryI
var i = 1
i.className // error: 'Int' does not have a member named 'className'
If you want to get the type of a primitive, you have to use bridgeToObjectiveC()
. Example:
var i = 1
i.bridgeToObjectiveC().className // __NSCFNumber
import Cocoa
.
className
is part of Cocoa's AppleScript support and should definitely not be used for generic introspection. Obviously it's not available on iOS.
You can use reflect to get information about object. For example name of object class:
var classname = reflect(now).summary
reflect(x).summary
-- thanks!
Xcode 8 Swift 3.0 use type(of:)
let className = "\(type(of: instance))"
I had luck with:
let className = NSStringFromClass(obj.dynamicType)
In Xcode 8, Swift 3.0
Steps:
1. Get the Type:
Option 1:
let type : Type = MyClass.self //Determines Type from Class
Option 2:
let type : Type = type(of:self) //Determines Type from self
2. Convert Type to String:
let string : String = "\(type)" //String
In Swift 3.0, you can use type(of:)
, as dynamicType
keyword has been removed.
SWIFT 5
With the latest release of Swift 3 we can get pretty descriptions of type names through the String
initializer. Like, for example print(String(describing: type(of: object)))
. Where object
can be an instance variable like array, a dictionary, an Int
, a NSDate
, an instance of a custom class, etc.
Here is my complete answer: Get class name of object as string in Swift
That question is looking for a way to getting the class name of an object as string but, also i proposed another way to getting the class name of a variable that isn't subclass of NSObject
. Here it is:
class Utility{
class func classNameAsString(obj: Any) -> String {
//prints more readable results for dictionaries, arrays, Int, etc
return String(describing: type(of: obj))
}
}
I made a static function which takes as parameter an object of type Any
and returns its class name as String
:) .
I tested this function with some variables like:
let diccionary: [String: CGFloat] = [:]
let array: [Int] = []
let numInt = 9
let numFloat: CGFloat = 3.0
let numDouble: Double = 1.0
let classOne = ClassOne()
let classTwo: ClassTwo? = ClassTwo()
let now = NSDate()
let lbl = UILabel()
and the output was:
diccionary is of type Dictionary
array is of type Array
numInt is of type Int
numFloat is of type CGFloat
numDouble is of type Double
classOne is of type: ClassOne
classTwo is of type: ClassTwo
now is of type: Date
lbl is of type: UILabel
When using Cocoa (not CocoaTouch), you can use the className
property for objects that are subclasses of NSObject.
println(now.className)
This property is not available for normal Swift objects, which aren't subclasses of NSObject (and in fact, there is no root id or object type in Swift).
class Person {
var name: String?
}
var p = Person()
println(person.className) // <- Compiler error
In CocoaTouch, at this time there is not a way to get a string description of the type of a given variable. Similar functionality also does not exist for primitive types in either Cocoa or CocoaTouch.
The Swift REPL is able to print out a summary of values including its type, so it is possible this manner of introspection will be possible via an API in the future.
EDIT: dump(object)
seems to do the trick.
dump(object)
is really powerful. Thank you.
The top answer doesn't have a working example of the new way of doing this using type(of:
. So to help rookies like me, here is a working example, taken mostly from Apple's docs here - https://developer.apple.com/documentation/swift/2885064-type
doubleNum = 30.1
func printInfo(_ value: Any) {
let varType = type(of: value)
print("'\(value)' of type '\(varType)'")
}
printInfo(doubleNum)
//'30.1' of type 'Double'
I've tried some of the other answers here but milage seems to very on what the underling object is.
However I did found a way you can get the Object-C class name for an object by doing the following:
now?.superclass as AnyObject! //replace now with the object you are trying to get the class name for
Here is and example of how you would use it:
let now = NSDate()
println("what is this = \(now?.superclass as AnyObject!)")
In this case it will print NSDate in the console.
I found this solution which hopefully might work for someone else. I created a class method to access the value. Please bear in mind this will work for NSObject subclass only. But at least is a clean and tidy solution.
class var className: String!{
let classString : String = NSStringFromClass(self.classForCoder())
return classString.componentsSeparatedByString(".").last;
}
In the latest XCode 6.3 with Swift 1.2, this is the only way I found:
if view.classForCoder.description() == "UISegment" {
...
}
<swift module name>.<actual class name>
, so you want to split the string with a .
and get the last token.
Many of the answers here do not work with the latest Swift (Xcode 7.1.1 at time of writing).
The current way of getting the information is to create a Mirror
and interrogate that. For the classname it is as simple as:
let mirror = Mirror(reflecting: instanceToInspect)
let classname:String = mirror.description
Additional information about the object can also be retrieved from the Mirror
. See http://swiftdoc.org/v2.1/type/Mirror/ for details.
To get a type of object or class of object in Swift, you must need to use a type(of: yourObject)
type(of: yourObject)
In lldb as of beta 5, you can see the class of an object with the command:
fr v -d r shipDate
which outputs something like:
(DBSalesOrderShipDate_DBSalesOrderShipDate_ *) shipDate = 0x7f859940
The command expanded out means something like:
Frame Variable
(print a frame variable) -d run_target
(expand dynamic types)
Something useful to know is that using "Frame Variable" to output variable values guarantees no code is executed.
I've found a solution for self-developed classes (or such you have access to).
Place the following computed property within your objects class definition:
var className: String? {
return __FILE__.lastPathComponent.stringByDeletingPathExtension
}
Now you can simply call the class name on your object like so:
myObject.className
Please note that this will only work if your class definition is made within a file that is named exactly like the class you want the name of.
As this is commonly the case the above answer should do it for most cases. But in some special cases you might need to figure out a different solution.
If you need the class name within the class (file) itself you can simply use this line:
let className = __FILE__.lastPathComponent.stringByDeletingPathExtension
Maybe this method helps some people out there.
Based on the answers and comments given by Klass and Kevin Ballard above, I would go with:
println(_stdlib_getDemangledTypeName(now).componentsSeparatedByString(".").last!)
println(_stdlib_getDemangledTypeName(soon).componentsSeparatedByString(".").last!)
println(_stdlib_getDemangledTypeName(soon?).componentsSeparatedByString(".").last!)
println(_stdlib_getDemangledTypeName(soon!).componentsSeparatedByString(".").last!)
println(_stdlib_getDemangledTypeName(myvar0).componentsSeparatedByString(".").last!)
println(_stdlib_getDemangledTypeName(myvar1).componentsSeparatedByString(".").last!)
println(_stdlib_getDemangledTypeName(myvar2).componentsSeparatedByString(".").last!)
println(_stdlib_getDemangledTypeName(myvar3).componentsSeparatedByString(".").last!)
which will print out:
"NSDate"
"ImplicitlyUnwrappedOptional"
"Optional"
"NSDate"
"NSString"
"PureSwiftClass"
"Int"
"Double"
toString(self.dynamicType).componentsSeparatedByString(".").last!
, obviously I was in an object context and able to reference self
.
let i: Int = 20
func getTypeName(v: Any) -> String {
let fullName = _stdlib_demangleName(_stdlib_getTypeName(i))
if let range = fullName.rangeOfString(".") {
return fullName.substringFromIndex(range.endIndex)
}
return fullName
}
println("Var type is \(getTypeName(i)) = \(i)")
Swift version 4:
print("\(type(of: self)) ,\(#function)")
// within a function of a class
Thanks @Joshua Dance
Swift 4:
// "TypeName"
func stringType(of some: Any) -> String {
let string = (some is Any.Type) ? String(describing: some) : String(describing: type(of: some))
return string
}
// "ModuleName.TypeName"
func fullStringType(of some: Any) -> String {
let string = (some is Any.Type) ? String(reflecting: some) : String(reflecting: type(of: some))
return string
}
Usage:
print(stringType(of: SomeClass())) // "SomeClass"
print(stringType(of: SomeClass.self)) // "SomeClass"
print(stringType(of: String())) // "String"
print(fullStringType(of: String())) // "Swift.String"
There appears to be no generic way to print the type name of an arbitrary value's type. As others have noted, for class instances you can print value.className
but for primitive values it appears that at runtime, the type information is gone.
For instance, it looks as if there's not a way to type: 1.something()
and get out Int
for any value of something
. (You can, as another answer suggested, use i.bridgeToObjectiveC().className
to give you a hint, but __NSCFNumber
is not actually the type of i
-- just what it will be converted to when it crosses the boundary of an Objective-C function call.)
I would be happy to be proven wrong, but it looks like the type checking is all done at compile time, and like C++ (with RTTI disabled) much of the type information is gone at runtime.
This is how you get a type string of your object or Type which is consistent and takes into account to which module the object definition belongs to or nested in. Works in Swift 4.x.
@inline(__always) func typeString(for _type: Any.Type) -> String {
return String(reflecting: type(of: _type))
}
@inline(__always) func typeString(for object: Any) -> String {
return String(reflecting: type(of: type(of: object)))
}
struct Lol {
struct Kek {}
}
// if you run this in playground the results will be something like
typeString(for: Lol.self) // __lldb_expr_74.Lol.Type
typeString(for: Lol()) // __lldb_expr_74.Lol.Type
typeString(for: Lol.Kek.self)// __lldb_expr_74.Lol.Kek.Type
typeString(for: Lol.Kek()) // __lldb_expr_74.Lol.Kek.Type
Not exactly what you are after, but you can also check the type of the variable against Swift types like so:
let object: AnyObject = 1
if object is Int {
}
else if object is String {
}
For example.
Xcode 7.3.1, Swift 2.2:
String(instanceToPrint.self).componentsSeparatedByString(".").last
Success story sharing
_stdlib_getTypeName()
? The integrated REPL no longer exists,swift-ide-test
doesn't exist either, and Xcode's printing of the Swift module elides_
-prefixed values.lldb
easily enough in the repl. There's also_stdlib_getDemangledTypeName()
, and_stdlib_demangleName()
.image
was a shortcut fortarget modules
. I ended up usingtarget modules lookup -r -n _stdlib_
, which of course is better-expressed asimage lookup -r -n _stdlib_ libswiftCore.dylib
dynamicType
keyword has been removed from Swift. In its place a new primitive functiontype(of:)
has been added to the language: github.com/apple/swift/blob/master/CHANGELOG.md