Reply to http://ericasadun.com/2016/04/18/default-reflection/

DefaultReflectable.swift

import Foundation

/// A reference type that provides a better default representation than the class name
public protocol DefaultReflectable: Streamable {}

/// A default implementation that enables class members to display their values
extension DefaultReflectable {
    /// Constructs a better representation using reflection
    internal func DefaultDescription<T>(instance: T) -> String {
        let mirror = Mirror(reflecting: instance)
        let chunks = mirror.children.map({
            (label: String?, value: Any) -> String in
            if let label = label {
                if value is String {
                    return "\(label): \"\(value)\""
                }
                return "\(label): \(value)"
            } else {
                return "\(value)"
            }
        })
        if chunks.isEmpty {
            return "\(instance)"
        } else {
            let chunksString = chunks.joinWithSeparator(", ")
            return "\(mirror.subjectType)(\(chunksString))"
        }
    }
    
    public func writeTo<Target : OutputStreamType>(inout target: Target) {
        target.write(DefaultDescription(self))
    }
}

struct S1 {var a = 1; var b = "x"}
class C1 {var a = 1; var b = "x"}
class C2: DefaultReflectable {var a = 1; var b = "x"}
class C3: NSObject {var a = 1; var b = "x"}
class C4: NSObject, DefaultReflectable {var a = 1; var b = "x"}

print(S1()) // S1(a: 1, b: "x")
print(C1()) // C1
print(C2()) // C2(a: 1, b: "x")
print(C3()) // <__lldb_expr_163.C3: 0x7fb52452dc00>
print(C4()) // C4(a: 1, b: "x")