是否有一种方法可以在swift中打印变量的运行时类型?例如:
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
在上面的例子中，我正在寻找一种方法来显示变量“soon”的类型是ImplicitlyUnwrappedOptional<NSDate>，或至少NSDate!
当前回答
斯威夫特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>"
其他回答
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)")
你可以使用reflect来获取关于对象的信息。 例如对象类的名称:
var classname = reflect(now).summary
这就是如何获得对象或type的类型字符串，它是一致的，并考虑到对象定义属于哪个模块或嵌套在哪个模块中。适用于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
这里的许多答案都不支持最新的Swift(本文撰写时为Xcode 7.1.1)。
目前获取信息的方法是创建一个Mirror并对其进行询问。对于类名，它很简单:
let mirror = Mirror(reflecting: instanceToInspect)
let classname:String = mirror.description
关于对象的其他信息也可以从镜像中检索。详情见http://swiftdoc.org/v2.1/type/Mirror/。
我目前的Xcode版本是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).")
}
}
输出:
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.
