如何在Swift中打印一个变量的类型或类?
有没有办法在swift中打印一个变量的运行时类型?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ImplicitlyUnwrappedOptional,或至少NSDate!。
2016年9月更新
Swift 3.0:使用类型(of :),例如type(of:someThing)(因为dynamicType关键字已被删除) 2015年10月更新: 我更新了下面的例子到新的Swift 2.0语法(例如println被替换为print,toString()现在是String())。 从Xcode 6.3发行说明: @nschum指出在Xcode 6.3 release notes显示另一种方式的意见:
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)") 其中输出: 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> 更新Xcode 6.3: 您可以使用_stdlib_getDemangledTypeName(): print( "TypeName0 = (_stdlib_getDemangledTypeName(myvar0))") print( "TypeName1 = (_stdlib_getDemangledTypeName(myvar1))") print( "TypeName2 = (_stdlib_getDemangledTypeName(myvar2))") print( "TypeName3 = (_stdlib_getDemangledTypeName(myvar3))") 并将其作为输出: TypeName0 = NSString TypeName1 = __lldb_expr_26.PureSwiftClass TypeName2 = Swift.Int TypeName3 = Swift.String 原始答案: 在Xcode 6.3之前_stdlib_getTypeName获取变量的受损类型名称。 Ewan Swick’s blog entry帮助解密这些字符串: 例如_TtSi代表Swift的内部Int类型。 Mike Ash has a great blog entry covering the same topic。 (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |