diff --git a/ASN1Decoder.xcodeproj/project.pbxproj b/ASN1Decoder.xcodeproj/project.pbxproj
index ceee68b..2a19c54 100644
--- a/ASN1Decoder.xcodeproj/project.pbxproj
+++ b/ASN1Decoder.xcodeproj/project.pbxproj
@@ -347,6 +347,7 @@
 		412A9E4D1F55C6500099110C /* Debug */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
+				APPLICATION_EXTENSION_API_ONLY = YES;
 				CLANG_ENABLE_MODULES = YES;
 				CODE_SIGN_IDENTITY = "";
 				"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "iPhone Developer";
@@ -371,6 +372,7 @@
 		412A9E4E1F55C6500099110C /* Release */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
+				APPLICATION_EXTENSION_API_ONLY = YES;
 				CLANG_ENABLE_MODULES = YES;
 				CODE_SIGN_IDENTITY = "";
 				"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "iPhone Developer";
diff --git a/ASN1Decoder/ASN1Identifier.swift b/ASN1Decoder/ASN1Identifier.swift
index 1c36314..9afa36c 100644
--- a/ASN1Decoder/ASN1Identifier.swift
+++ b/ASN1Decoder/ASN1Identifier.swift
@@ -24,7 +24,7 @@
 import Foundation
 
 
-class ASN1Identifier : CustomStringConvertible {
+public class ASN1Identifier : CustomStringConvertible {
     
     enum Class : UInt8 {
         case universal = 0x00
@@ -93,7 +93,7 @@ class ASN1Identifier : CustomStringConvertible {
         return TagNumber(rawValue: rawValue & 0x1F) ?? .endOfContent
     }
     
-    var description: String {
+    public var description: String {
         if typeClass() == .universal {
             return String(describing: tagNumber())
         }
diff --git a/ASN1Decoder/ASN1Object.swift b/ASN1Decoder/ASN1Object.swift
index 077f4d3..520fbf5 100644
--- a/ASN1Decoder/ASN1Object.swift
+++ b/ASN1Decoder/ASN1Object.swift
@@ -25,20 +25,20 @@
 import Foundation
 
 
-public class ASN1Object : CustomStringConvertible {
+open class ASN1Object : CustomStringConvertible {
     
     init() {
     }
     
-    var rawValue: Data?
+    public internal(set) var rawValue: Data?
     
-    var identifier: ASN1Identifier?
+    public internal(set) var identifier: ASN1Identifier?
     
-    var value: Any?
+    public internal(set) var value: Any?
     
-    var sub: [ASN1Object]?
+    public internal(set) var sub: [ASN1Object]?
     
-    weak var parent: ASN1Object?
+    public internal(set) weak var parent: ASN1Object?
     
     
     func sub(_ index: Int) -> ASN1Object? {
diff --git a/ASN1Decoder/Asn1Decoder.swift b/ASN1Decoder/Asn1Decoder.swift
index 657b9cf..2466f22 100644
--- a/ASN1Decoder/Asn1Decoder.swift
+++ b/ASN1Decoder/Asn1Decoder.swift
@@ -24,7 +24,7 @@
 import Foundation
 
 
-public class ASN1DERDecoder {
+open class ASN1DERDecoder {
     
     public static func decode(data: Data) throws -> [ASN1Object] {
         var iterator = data.makeIterator()