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

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

其他回答

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/。

您仍然可以通过className(返回String)访问该类。

实际上有几种方法来获取类,例如classForArchiver, classForCoder, classForKeyedArchiver(都返回AnyClass!)

无法获取原语的类型(原语不是类)。

例子:

var ivar = [:]
ivar.className // __NSDictionaryI

var i = 1
i.className // error: 'Int' does not have a member named 'className'

如果你想获取一个原语的类型,你必须使用bridgetooobjecvec()。例子:

var i = 1
i.bridgeToObjectiveC().className // __NSCFNumber

上面的答案没有使用type(of:的新方法的工作示例。所以为了帮助像我这样的新手,这里有一个工作的例子,主要来自苹果的文档- 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'

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>"
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)")