diff --git a/Aspects.m b/Aspects.m
index c907066..612fd36 100644
--- a/Aspects.m
+++ b/Aspects.m
@@ -45,7 +45,7 @@ - (id)initWithInstance:(__unsafe_unretained id)instance invocation:(NSInvocation
 @end
 
 // Tracks a single aspect.
-@interface AspectIdentifier : NSObject
+@interface AspectIdentifier : NSObject <AspectToken>
 + (instancetype)identifierWithSelector:(SEL)selector object:(id)object options:(AspectOptions)options block:(id)block error:(NSError **)error;
 - (BOOL)invokeWithInfo:(id<AspectInfo>)info;
 @property (nonatomic, assign) SEL selector;
diff --git a/AspectsDemo/AspectsDemo.xcodeproj/project.pbxproj b/AspectsDemo/AspectsDemo.xcodeproj/project.pbxproj
index ecec2b8..acb3d0b 100644
--- a/AspectsDemo/AspectsDemo.xcodeproj/project.pbxproj
+++ b/AspectsDemo/AspectsDemo.xcodeproj/project.pbxproj
@@ -202,7 +202,7 @@
 			isa = PBXProject;
 			attributes = {
 				CLASSPREFIX = Aspects;
-				LastUpgradeCheck = 0510;
+				LastUpgradeCheck = 0900;
 				ORGANIZATIONNAME = "PSPDFKit GmbH";
 				TargetAttributes = {
 					78573F0B19155A2E000D3B00 = {
@@ -307,18 +307,30 @@
 				CLANG_CXX_LIBRARY = "libc++";
 				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_ARC = YES;
+				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
 				CLANG_WARN_BOOL_CONVERSION = YES;
+				CLANG_WARN_COMMA = YES;
 				CLANG_WARN_CONSTANT_CONVERSION = YES;
 				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
 				CLANG_WARN_EMPTY_BODY = YES;
 				CLANG_WARN_ENUM_CONVERSION = YES;
+				CLANG_WARN_INFINITE_RECURSION = YES;
 				CLANG_WARN_INT_CONVERSION = YES;
+				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
+				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
+				CLANG_WARN_STRICT_PROTOTYPES = YES;
+				CLANG_WARN_SUSPICIOUS_MOVE = YES;
+				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
 				"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "iPhone Developer";
 				COPY_PHASE_STRIP = NO;
+				ENABLE_STRICT_OBJC_MSGSEND = YES;
+				ENABLE_TESTABILITY = YES;
 				GCC_C_LANGUAGE_STANDARD = gnu99;
 				GCC_DYNAMIC_NO_PIC = NO;
+				GCC_NO_COMMON_BLOCKS = YES;
 				GCC_OPTIMIZATION_LEVEL = 0;
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"DEBUG=1",
@@ -331,7 +343,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 6.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
 				TARGETED_DEVICE_FAMILY = "1,2";
@@ -363,25 +375,36 @@
 				CLANG_CXX_LIBRARY = "libc++";
 				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_ARC = YES;
+				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
 				CLANG_WARN_BOOL_CONVERSION = YES;
+				CLANG_WARN_COMMA = YES;
 				CLANG_WARN_CONSTANT_CONVERSION = YES;
 				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
 				CLANG_WARN_EMPTY_BODY = YES;
 				CLANG_WARN_ENUM_CONVERSION = YES;
+				CLANG_WARN_INFINITE_RECURSION = YES;
 				CLANG_WARN_INT_CONVERSION = YES;
+				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
+				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
+				CLANG_WARN_STRICT_PROTOTYPES = YES;
+				CLANG_WARN_SUSPICIOUS_MOVE = YES;
+				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
 				"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "iPhone Developer";
 				COPY_PHASE_STRIP = YES;
 				ENABLE_NS_ASSERTIONS = NO;
+				ENABLE_STRICT_OBJC_MSGSEND = YES;
 				GCC_C_LANGUAGE_STANDARD = gnu99;
+				GCC_NO_COMMON_BLOCKS = YES;
 				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
 				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
 				GCC_WARN_UNDECLARED_SELECTOR = YES;
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 6.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
 				SDKROOT = iphoneos;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				VALIDATE_PRODUCT = YES;
@@ -413,6 +436,7 @@
 				GCC_PRECOMPILE_PREFIX_HEADER = YES;
 				GCC_PREFIX_HEADER = "AspectsDemo/AspectsDemo-Prefix.pch";
 				INFOPLIST_FILE = "AspectsDemo/AspectsDemo-Info.plist";
+				PRODUCT_BUNDLE_IDENTIFIER = "com.pspdfkit.aspects.${PRODUCT_NAME:rfc1034identifier}";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				WRAPPER_EXTENSION = app;
 			};
@@ -426,6 +450,7 @@
 				GCC_PRECOMPILE_PREFIX_HEADER = YES;
 				GCC_PREFIX_HEADER = "AspectsDemo/AspectsDemo-Prefix.pch";
 				INFOPLIST_FILE = "AspectsDemo/AspectsDemo-Info.plist";
+				PRODUCT_BUNDLE_IDENTIFIER = "com.pspdfkit.aspects.${PRODUCT_NAME:rfc1034identifier}";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				WRAPPER_EXTENSION = app;
 			};
@@ -447,6 +472,7 @@
 					"$(inherited)",
 				);
 				INFOPLIST_FILE = "AspectsDemoTests/AspectsDemoTests-Info.plist";
+				PRODUCT_BUNDLE_IDENTIFIER = "com.pspdfkit.aspects.${PRODUCT_NAME:rfc1034identifier}";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				TEST_HOST = "$(BUNDLE_LOADER)";
 				WRAPPER_EXTENSION = xctest;
@@ -465,6 +491,7 @@
 				GCC_PRECOMPILE_PREFIX_HEADER = YES;
 				GCC_PREFIX_HEADER = "AspectsDemo/AspectsDemo-Prefix.pch";
 				INFOPLIST_FILE = "AspectsDemoTests/AspectsDemoTests-Info.plist";
+				PRODUCT_BUNDLE_IDENTIFIER = "com.pspdfkit.aspects.${PRODUCT_NAME:rfc1034identifier}";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				TEST_HOST = "$(BUNDLE_LOADER)";
 				WRAPPER_EXTENSION = xctest;
diff --git a/AspectsDemo/AspectsDemo.xcodeproj/xcshareddata/xcschemes/AspectsDemo.xcscheme b/AspectsDemo/AspectsDemo.xcodeproj/xcshareddata/xcschemes/AspectsDemo.xcscheme
index 1b0cf72..9cdc51f 100644
--- a/AspectsDemo/AspectsDemo.xcodeproj/xcshareddata/xcschemes/AspectsDemo.xcscheme
+++ b/AspectsDemo/AspectsDemo.xcodeproj/xcshareddata/xcschemes/AspectsDemo.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0510"
+   LastUpgradeVersion = "0900"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
@@ -23,10 +23,11 @@
       </BuildActionEntries>
    </BuildAction>
    <TestAction
+      buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
-      shouldUseLaunchSchemeArgsEnv = "YES"
-      buildConfiguration = "Debug">
+      language = ""
+      shouldUseLaunchSchemeArgsEnv = "YES">
       <Testables>
          <TestableReference
             skipped = "NO">
@@ -48,17 +49,22 @@
             ReferencedContainer = "container:AspectsDemo.xcodeproj">
          </BuildableReference>
       </MacroExpansion>
+      <AdditionalOptions>
+      </AdditionalOptions>
    </TestAction>
    <LaunchAction
+      buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      language = ""
       launchStyle = "0"
       useCustomWorkingDirectory = "NO"
-      buildConfiguration = "Debug"
       ignoresPersistentStateOnLaunch = "NO"
       debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
       allowLocationSimulation = "YES">
-      <BuildableProductRunnable>
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
          <BuildableReference
             BuildableIdentifier = "primary"
             BlueprintIdentifier = "78573EF019155A2E000D3B00"
@@ -76,12 +82,13 @@
       </AdditionalOptions>
    </LaunchAction>
    <ProfileAction
+      buildConfiguration = "Release"
       shouldUseLaunchSchemeArgsEnv = "YES"
       savedToolIdentifier = ""
       useCustomWorkingDirectory = "NO"
-      buildConfiguration = "Release"
       debugDocumentVersioning = "YES">
-      <BuildableProductRunnable>
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
          <BuildableReference
             BuildableIdentifier = "primary"
             BlueprintIdentifier = "78573EF019155A2E000D3B00"
diff --git a/AspectsDemo/AspectsDemo/AspectsDemo-Info.plist b/AspectsDemo/AspectsDemo/AspectsDemo-Info.plist
index 5e1b0a5..6a012bd 100644
--- a/AspectsDemo/AspectsDemo/AspectsDemo-Info.plist
+++ b/AspectsDemo/AspectsDemo/AspectsDemo-Info.plist
@@ -9,7 +9,7 @@
 	<key>CFBundleExecutable</key>
 	<string>${EXECUTABLE_NAME}</string>
 	<key>CFBundleIdentifier</key>
-	<string>com.pspdfkit.aspects.${PRODUCT_NAME:rfc1034identifier}</string>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
 	<key>CFBundleInfoDictionaryVersion</key>
 	<string>6.0</string>
 	<key>CFBundleName</key>
diff --git a/AspectsDemo/AspectsDemo/AspectsViewController.xib b/AspectsDemo/AspectsDemo/AspectsViewController.xib
index 2e4af86..f962150 100644
--- a/AspectsDemo/AspectsDemo/AspectsViewController.xib
+++ b/AspectsDemo/AspectsDemo/AspectsViewController.xib
@@ -1,8 +1,12 @@
-<?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="5056" systemVersion="13C1021" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES">
+<?xml version="1.0" encoding="UTF-8"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="13196" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" colorMatched="YES">
+    <device id="retina4_7" orientation="portrait">
+        <adaptation id="fullscreen"/>
+    </device>
     <dependencies>
-        <deployment defaultVersion="1536" identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="3733"/>
+        <deployment version="2048" identifier="iOS"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="13173"/>
+        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
     <objects>
         <placeholder placeholderIdentifier="IBFilesOwner" id="-1" userLabel="File's Owner" customClass="AspectsViewController">
@@ -12,29 +16,26 @@
         </placeholder>
         <placeholder placeholderIdentifier="IBFirstResponder" id="-2" customClass="UIResponder"/>
         <view clearsContextBeforeDrawing="NO" contentMode="scaleToFill" id="i5M-Pr-FkT">
-            <rect key="frame" x="0.0" y="0.0" width="320" height="568"/>
+            <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
             <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
             <subviews>
                 <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="gKX-p5-Qxl">
-                    <rect key="frame" x="43" y="269" width="235" height="30"/>
-                    <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
+                    <rect key="frame" x="43" y="269" width="290" height="129"/>
                     <state key="normal" title="Present hooked System Controller">
-                        <color key="titleShadowColor" white="0.5" alpha="1" colorSpace="calibratedWhite"/>
+                        <color key="titleShadowColor" red="0.5" green="0.5" blue="0.5" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
                     </state>
                     <connections>
                         <action selector="buttonPressed:" destination="-2" eventType="touchUpInside" id="GAj-Jc-g4a"/>
                     </connections>
                 </button>
             </subviews>
-            <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="calibratedWhite"/>
+            <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
             <constraints>
                 <constraint firstAttribute="trailing" secondItem="gKX-p5-Qxl" secondAttribute="trailing" constant="42" id="2Xt-SA-Rbc"/>
                 <constraint firstItem="gKX-p5-Qxl" firstAttribute="leading" secondItem="i5M-Pr-FkT" secondAttribute="leading" constant="43" id="93u-8g-6Sl"/>
                 <constraint firstAttribute="bottom" secondItem="gKX-p5-Qxl" secondAttribute="bottom" constant="269" id="9Ns-Ri-BGy"/>
                 <constraint firstItem="gKX-p5-Qxl" firstAttribute="top" secondItem="i5M-Pr-FkT" secondAttribute="top" constant="269" id="gRf-at-BdM"/>
             </constraints>
-            <simulatedStatusBarMetrics key="simulatedStatusBarMetrics"/>
-            <simulatedScreenMetrics key="simulatedDestinationMetrics" type="retina4"/>
         </view>
     </objects>
 </document>
diff --git a/AspectsDemo/AspectsDemoTests/AspectsDemoTests-Info.plist b/AspectsDemo/AspectsDemoTests/AspectsDemoTests-Info.plist
index e4881ad..169b6f7 100644
--- a/AspectsDemo/AspectsDemoTests/AspectsDemoTests-Info.plist
+++ b/AspectsDemo/AspectsDemoTests/AspectsDemoTests-Info.plist
@@ -7,7 +7,7 @@
 	<key>CFBundleExecutable</key>
 	<string>${EXECUTABLE_NAME}</string>
 	<key>CFBundleIdentifier</key>
-	<string>com.pspdfkit.aspects.${PRODUCT_NAME:rfc1034identifier}</string>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
 	<key>CFBundleInfoDictionaryVersion</key>
 	<string>6.0</string>
 	<key>CFBundlePackageType</key>