diff --git a/SnapKit.xcodeproj/project.pbxproj b/SnapKit.xcodeproj/project.pbxproj
index 7221d08..91d18f6 100644
--- a/SnapKit.xcodeproj/project.pbxproj
+++ b/SnapKit.xcodeproj/project.pbxproj
@@ -302,16 +302,16 @@
 			isa = PBXProject;
 			attributes = {
 				LastSwiftUpdateCheck = 0720;
-				LastUpgradeCheck = 0820;
+				LastUpgradeCheck = 0900;
 				ORGANIZATIONNAME = "SnapKit Team";
 				TargetAttributes = {
 					EEBCC9D719CC627D0083B827 = {
 						CreatedOnToolsVersion = 6.0;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0900;
 					};
 					EEBCC9E119CC627D0083B827 = {
 						CreatedOnToolsVersion = 6.0;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0900;
 						ProvisioningStyle = Automatic;
 					};
 				};
@@ -412,14 +412,20 @@
 				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;
@@ -463,14 +469,20 @@
 				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;
@@ -513,6 +525,7 @@
 				SKIP_INSTALL = YES;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_VERSION = 4.0;
 				VERSIONING_SYSTEM = "apple-generic";
 			};
 			name = Debug;
@@ -532,6 +545,7 @@
 				PRODUCT_NAME = SnapKit;
 				SKIP_INSTALL = YES;
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
+				SWIFT_VERSION = 4.0;
 				VERSIONING_SYSTEM = "apple-generic";
 			};
 			name = Release;
@@ -545,7 +559,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks @loader_path/../Frameworks @executable_path/../Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "io.snapkit.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -559,7 +573,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "io.snapkit.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};
diff --git a/SnapKit.xcodeproj/xcshareddata/xcschemes/SnapKit.xcscheme b/SnapKit.xcodeproj/xcshareddata/xcschemes/SnapKit.xcscheme
index 5760875..48ec452 100644
--- a/SnapKit.xcodeproj/xcshareddata/xcschemes/SnapKit.xcscheme
+++ b/SnapKit.xcodeproj/xcshareddata/xcschemes/SnapKit.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0820"
+   LastUpgradeVersion = "0900"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/Source/Constraint.swift b/Source/Constraint.swift
index a4ec7f1..cd53ade 100644
--- a/Source/Constraint.swift
+++ b/Source/Constraint.swift
@@ -166,7 +166,7 @@ public final class Constraint {
             layoutConstraint.label = self.label
 
             // set priority
-            layoutConstraint.priority = self.priority.constraintPriorityTargetValue
+            layoutConstraint.priority = UILayoutPriority(rawValue: self.priority.constraintPriorityTargetValue)
 
             // set constraint
             layoutConstraint.constraint = self
@@ -243,8 +243,8 @@ public final class Constraint {
             layoutConstraint.constant = self.constant.constraintConstantTargetValueFor(layoutAttribute: attribute)
 
             let requiredPriority = ConstraintPriority.required.value
-            if (layoutConstraint.priority < requiredPriority), (self.priority.constraintPriorityTargetValue != requiredPriority) {
-                layoutConstraint.priority = self.priority.constraintPriorityTargetValue
+            if (layoutConstraint.priority.rawValue < requiredPriority), (self.priority.constraintPriorityTargetValue != requiredPriority) {
+                layoutConstraint.priority = UILayoutPriority(rawValue: self.priority.constraintPriorityTargetValue)
             }
         }
     }
diff --git a/Source/ConstraintDSL.swift b/Source/ConstraintDSL.swift
index ed7b7e5..a7e1798 100644
--- a/Source/ConstraintDSL.swift
+++ b/Source/ConstraintDSL.swift
@@ -39,10 +39,10 @@ public protocol ConstraintDSL {
 extension ConstraintDSL {
     
     public func setLabel(_ value: String?) {
-        objc_setAssociatedObject(self.target, &labelKey, value, .OBJC_ASSOCIATION_COPY_NONATOMIC)
+        objc_setAssociatedObject(self.target as Any, &labelKey, value, .OBJC_ASSOCIATION_COPY_NONATOMIC)
     }
     public func label() -> String? {
-        return objc_getAssociatedObject(self.target, &labelKey) as? String
+        return objc_getAssociatedObject(self.target as Any, &labelKey) as? String
     }
     
 }
diff --git a/Source/ConstraintViewDSL.swift b/Source/ConstraintViewDSL.swift
index 8b38d32..4485da4 100644
--- a/Source/ConstraintViewDSL.swift
+++ b/Source/ConstraintViewDSL.swift
@@ -53,37 +53,37 @@ public struct ConstraintViewDSL: ConstraintAttributesDSL {
     
     public var contentHuggingHorizontalPriority: Float {
         get {
-            return self.view.contentHuggingPriority(for: .horizontal)
+            return self.view.contentHuggingPriority(for: .horizontal).rawValue
         }
         set {
-            self.view.setContentHuggingPriority(newValue, for: .horizontal)
+            self.view.setContentHuggingPriority(UILayoutPriority(rawValue: newValue), for: .horizontal)
         }
     }
     
     public var contentHuggingVerticalPriority: Float {
         get {
-            return self.view.contentHuggingPriority(for: .vertical)
+            return self.view.contentHuggingPriority(for: .vertical).rawValue
         }
         set {
-            self.view.setContentHuggingPriority(newValue, for: .vertical)
+            self.view.setContentHuggingPriority(UILayoutPriority(rawValue: newValue), for: .vertical)
         }
     }
     
     public var contentCompressionResistanceHorizontalPriority: Float {
         get {
-            return self.view.contentCompressionResistancePriority(for: .horizontal)
+            return self.view.contentCompressionResistancePriority(for: .horizontal).rawValue
         }
         set {
-            self.view.setContentCompressionResistancePriority(newValue, for: .horizontal)
+            self.view.setContentCompressionResistancePriority(UILayoutPriority(rawValue: newValue), for: .horizontal)
         }
     }
     
     public var contentCompressionResistanceVerticalPriority: Float {
         get {
-            return self.view.contentCompressionResistancePriority(for: .vertical)
+            return self.view.contentCompressionResistancePriority(for: .vertical).rawValue
         }
         set {
-            self.view.setContentCompressionResistancePriority(newValue, for: .vertical)
+            self.view.setContentCompressionResistancePriority(UILayoutPriority(rawValue: newValue), for: .vertical)
         }
     }
     
diff --git a/Source/Debugging.swift b/Source/Debugging.swift
index fdc505d..d57dde5 100644
--- a/Source/Debugging.swift
+++ b/Source/Debugging.swift
@@ -66,7 +66,7 @@ public extension LayoutConstraint {
             }
         }
         
-        if self.priority != 1000.0 {
+        if self.priority.rawValue != 1000.0 {
             description += " ^\(self.priority)"
         }
         
diff --git a/Tests/Tests.swift b/Tests/Tests.swift
index e232fcc..34f74ac 100644
--- a/Tests/Tests.swift
+++ b/Tests/Tests.swift
@@ -542,7 +542,7 @@ class SnapKitTests: XCTestCase {
 
     func testPriorityStride() {
         let highPriority: ConstraintPriority = .high
-        let higherPriority: ConstraintPriority = .high + 1
+        let higherPriority: ConstraintPriority = ConstraintPriority.high.advanced(by: 1)
         XCTAssertEqual(higherPriority.value, highPriority.value + 1)
     }
 }