diff --git a/DropdownMenu.xcodeproj/project.pbxproj b/DropdownMenu.xcodeproj/project.pbxproj
index dff4ff8..de08a39 100644
--- a/DropdownMenu.xcodeproj/project.pbxproj
+++ b/DropdownMenu.xcodeproj/project.pbxproj
@@ -161,22 +161,24 @@
 					ACE6DB6B1CF74183005C6667 = {
 						CreatedOnToolsVersion = 7.3.1;
 						DevelopmentTeam = 7NLBE99QC4;
-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1020;
 						ProvisioningStyle = Automatic;
 					};
 					ACE6DB751CF74183005C6667 = {
 						CreatedOnToolsVersion = 7.3.1;
 						DevelopmentTeam = 7NLBE99QC4;
+						LastSwiftMigration = 1020;
 						ProvisioningStyle = Automatic;
 					};
 				};
 			};
 			buildConfigurationList = ACE6DB661CF74183005C6667 /* Build configuration list for PBXProject "DropdownMenu" */;
 			compatibilityVersion = "Xcode 3.2";
-			developmentRegion = English;
+			developmentRegion = en;
 			hasScannedForEncodings = 0;
 			knownRegions = (
 				en,
+				Base,
 			);
 			mainGroup = ACE6DB621CF74183005C6667;
 			productRefGroup = ACE6DB6D1CF74183005C6667 /* Products */;
@@ -369,7 +371,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
@@ -390,7 +392,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = com.teambition.DropdownMenu;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Release;
 		};
@@ -403,7 +405,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.teambition.DropdownMenuTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
@@ -416,7 +418,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.teambition.DropdownMenuTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Release;
 		};
diff --git a/DropdownMenu.xcworkspace/xcuserdata/wangwei.xcuserdatad/UserInterfaceState.xcuserstate b/DropdownMenu.xcworkspace/xcuserdata/wangwei.xcuserdatad/UserInterfaceState.xcuserstate
deleted file mode 100644
index 174cc3f..0000000
Binary files a/DropdownMenu.xcworkspace/xcuserdata/wangwei.xcuserdatad/UserInterfaceState.xcuserstate and /dev/null differ
diff --git a/DropdownMenu.xcworkspace/xcuserdata/wangwei.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist b/DropdownMenu.xcworkspace/xcuserdata/wangwei.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist
deleted file mode 100644
index ed9a9b4..0000000
--- a/DropdownMenu.xcworkspace/xcuserdata/wangwei.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist
+++ /dev/null
@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<Bucket
-   type = "0"
-   version = "2.0">
-</Bucket>
diff --git a/DropdownMenu.xcworkspace/xcuserdata/zhangxiaolian.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist b/DropdownMenu.xcworkspace/xcuserdata/zhangxiaolian.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist
deleted file mode 100644
index 1071dcf..0000000
--- a/DropdownMenu.xcworkspace/xcuserdata/zhangxiaolian.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist
+++ /dev/null
@@ -1,23 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<Bucket
-   type = "0"
-   version = "2.0">
-   <Breakpoints>
-      <BreakpointProxy
-         BreakpointExtensionID = "Xcode.Breakpoint.FileBreakpoint">
-         <BreakpointContent
-            shouldBeEnabled = "Yes"
-            ignoreCount = "0"
-            continueAfterRunningActions = "No"
-            filePath = "DropdownMenu/DropdownMenu.swift"
-            timestampString = "543491683.296456"
-            startingColumnNumber = "9223372036854775807"
-            endingColumnNumber = "9223372036854775807"
-            startingLineNumber = "145"
-            endingLineNumber = "145"
-            landmarkName = "updateForOrientationChange(_:)"
-            landmarkType = "7">
-         </BreakpointContent>
-      </BreakpointProxy>
-   </Breakpoints>
-</Bucket>
diff --git a/DropdownMenu/DropUpMenu.swift b/DropdownMenu/DropUpMenu.swift
index 1ab9c30..685b825 100644
--- a/DropdownMenu/DropUpMenu.swift
+++ b/DropdownMenu/DropUpMenu.swift
@@ -33,14 +33,24 @@ public extension DropUpMenuDelegate {
 private let screenRect = UIScreen.main.bounds
 
 open class DropUpMenu: UIView {
-    fileprivate var items: [DropdownItem] = []
-    fileprivate var selectedRow: Int
-    open var tableView: UITableView!
-    fileprivate var barCoverView: UIView!
-    fileprivate var isShow = false
-    fileprivate var addedWindow: UIWindow?
-    fileprivate var windowRootView: UIView?
-    fileprivate lazy var tapGestureRecognizer: UITapGestureRecognizer = {
+    private var items: [DropdownItem] = []
+    private var selectedRow: Int
+    open lazy var tableView: UITableView = {
+        let tableView = UITableView(frame: CGRect.zero, style: .grouped)
+        tableView.estimatedSectionHeaderHeight = 0
+        tableView.estimatedSectionFooterHeight = 0
+        return tableView
+    }()
+    private lazy var barCoverView: UIView = {
+        let barCoverView = UIView()
+        barCoverView.backgroundColor = UIColor.clear
+        barCoverView.translatesAutoresizingMaskIntoConstraints = false
+        return barCoverView
+    }()
+    private var isShow = false
+    private var addedWindow: UIWindow?
+    private var windowRootView: UIView?
+    private lazy var tapGestureRecognizer: UITapGestureRecognizer = {
         return UITapGestureRecognizer(target: self, action: #selector(self.hideMenu))
     }()
     
@@ -86,10 +96,10 @@ open class DropUpMenu: UIView {
         
         clipsToBounds = true
         setupGestureView()
-        initTableView()
+        setupTableView()
     }
     
-    fileprivate func setupGestureView() {
+    private func setupGestureView() {
         let gestureView = UIView()
         gestureView.backgroundColor = UIColor.clear
         addSubview(gestureView)
@@ -102,16 +112,13 @@ open class DropUpMenu: UIView {
         gestureView.addGestureRecognizer(tapGestureRecognizer)
     }
     
-    fileprivate func initTableView() {
-        tableView = UITableView(frame: CGRect.zero, style: .grouped)
-        tableView?.delegate = self
-        tableView?.dataSource = self
-        tableView.estimatedSectionHeaderHeight = 0
-        tableView.estimatedSectionFooterHeight = 0
+    private func setupTableView() {
+        tableView.delegate = self
+        tableView.dataSource = self
         addSubview(tableView)
     }
     
-    fileprivate func layoutTableView() {
+    private func layoutTableView() {
         tableViewHeight = CGFloat(items.count) * rowHeight
         let maxHeight = UIScreen.main.bounds.height - bottomOffsetY
         if tableViewHeight > maxHeight {
@@ -125,7 +132,7 @@ open class DropUpMenu: UIView {
         NSLayoutConstraint.activate([NSLayoutConstraint.init(item: tableView, attribute: .right, relatedBy: .equal, toItem: self, attribute: .right, multiplier: 1.0, constant: 0)])
     }
     
-    fileprivate func setupBottomSeperatorView() {
+    private func setupBottomSeperatorView() {
         let seperatorView = UIView()
         seperatorView.backgroundColor = tableViewSeperatorColor
         addSubview(seperatorView)
@@ -136,10 +143,7 @@ open class DropUpMenu: UIView {
         NSLayoutConstraint.activate([NSLayoutConstraint.init(item: seperatorView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 0.5)])
     }
     
-    fileprivate func setupBottomCoverView(on view: UIView) {
-        barCoverView = UIView()
-        barCoverView.backgroundColor = UIColor.clear
-        barCoverView.translatesAutoresizingMaskIntoConstraints = false
+    private func setupBottomCoverView(on view: UIView) {
         view.addSubview(barCoverView)
         NSLayoutConstraint.activate([NSLayoutConstraint.init(item: barCoverView, attribute: .bottom, relatedBy: .equal, toItem: view, attribute: .bottom, multiplier: 1.0, constant: 0)])
         NSLayoutConstraint.activate([NSLayoutConstraint.init(item: barCoverView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: bottomOffsetY)])
diff --git a/DropdownMenu/DropdownMenu.swift b/DropdownMenu/DropdownMenu.swift
index 742c9cd..0022bf3 100644
--- a/DropdownMenu/DropdownMenu.swift
+++ b/DropdownMenu/DropdownMenu.swift
@@ -33,23 +33,28 @@ public extension DropdownMenuDelegate {
 }
 
 open class DropdownMenu: UIView {
-    fileprivate weak var navigationController: UINavigationController!
+    private weak var navigationController: UINavigationController!
    
-    fileprivate var sections: [DropdownSection] = []
-    fileprivate var selectedIndexPath: IndexPath
+    private var sections: [DropdownSection] = []
+    private var selectedIndexPath: IndexPath
     
-    open var tableView: UITableView!
-    fileprivate var barCoverView: UIView?
+    open var tableView: UITableView = {
+        let tableView = UITableView(frame: CGRect.zero, style: .grouped)
+        tableView.estimatedSectionFooterHeight = 0
+        tableView.estimatedSectionHeaderHeight = 0
+        return tableView
+    }()
+    private var barCoverView: UIView?
     open var isShow = false
-    fileprivate var addedWindow: UIWindow?
-    fileprivate var windowRootView: UIView?
-    fileprivate var topConstraint: NSLayoutConstraint?
-    fileprivate var navigationBarCoverViewHeightConstraint: NSLayoutConstraint?
-    fileprivate var tableViewHeightConstraint: NSLayoutConstraint?
-    fileprivate let iPhoneXPortraitTopOffset: CGFloat = 88.0
-    fileprivate let portraitTopOffset: CGFloat = 64.0
-    fileprivate let landscapeTopOffset: CGFloat = 32.0
-    fileprivate var topLayoutConstraintConstant: CGFloat {
+    private var addedWindow: UIWindow?
+    private var windowRootView: UIView?
+    private var topConstraint: NSLayoutConstraint?
+    private var navigationBarCoverViewHeightConstraint: NSLayoutConstraint?
+    private var tableViewHeightConstraint: NSLayoutConstraint?
+    private let iPhoneXPortraitTopOffset: CGFloat = 88.0
+    private let portraitTopOffset: CGFloat = 64.0
+    private let landscapeTopOffset: CGFloat = 32.0
+    private var topLayoutConstraintConstant: CGFloat {
         var offset: CGFloat = 0
         if !navigationController.isNavigationBarHidden {
           offset = navigationController.navigationBar.frame.height + navigationController.navigationBar.frame.origin.y
@@ -108,7 +113,7 @@ open class DropdownMenu: UIView {
         
         clipsToBounds = true
         setupGestureView()
-        initTableView()
+        setupTableView()
         
         NotificationCenter.default.addObserver(self, selector: #selector(self.updateForOrientationChange(_:)), name: UIApplication.willChangeStatusBarOrientationNotification, object: nil)
     }
@@ -123,7 +128,7 @@ open class DropdownMenu: UIView {
         
         clipsToBounds = true
         setupGestureView()
-        initTableView()
+        setupTableView()
         
         NotificationCenter.default.addObserver(self, selector: #selector(self.updateForOrientationChange(_:)), name: UIApplication.willChangeStatusBarOrientationNotification, object: nil)
     }
@@ -186,7 +191,7 @@ open class DropdownMenu: UIView {
         }
     }
     
-    fileprivate func setupGestureView() {
+    private func setupGestureView() {
         let gestureView = UIView()
         gestureView.backgroundColor = UIColor.clear
         addSubview(gestureView)
@@ -199,17 +204,14 @@ open class DropdownMenu: UIView {
         gestureView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(hideMenu)))
     }
     
-    fileprivate func initTableView() {
-        tableView = UITableView(frame: CGRect.zero, style: .grouped)
+    private func setupTableView() {
         tableView.separatorStyle = separatorStyle
         tableView.delegate = self
         tableView.dataSource = self
-        tableView.estimatedSectionFooterHeight = 0
-        tableView.estimatedSectionHeaderHeight = 0
         addSubview(tableView)
     }
     
-    fileprivate func layoutTableView() {
+    private func layoutTableView() {
         tableView.translatesAutoresizingMaskIntoConstraints = false
 
         updateTableViewHeight()
@@ -222,7 +224,7 @@ open class DropdownMenu: UIView {
         self.tableViewHeightConstraint = tableViewHeightConstraint
     }
 
-    fileprivate func updateTableViewHeight() {
+    private func updateTableViewHeight() {
         tableViewHeight = tableviewHeight()
         
         let maxHeight = navigationController.view.frame.height - topLayoutConstraintConstant - defaultBottonMargin
@@ -236,7 +238,7 @@ open class DropdownMenu: UIView {
         }
     }
 
-    fileprivate func updateForSectionsChange(_ animations: (() -> Void)? = nil) {
+    private func updateForSectionsChange(_ animations: (() -> Void)? = nil) {
         updateTableViewHeight()
         tableViewHeightConstraint?.constant = tableViewHeight
         UIView.animate(withDuration: 0.3) { [weak self] in
@@ -248,7 +250,7 @@ open class DropdownMenu: UIView {
         }
     }
     
-    fileprivate func setupTopSeperatorView() {
+    private func setupTopSeperatorView() {
         let seperatorView = UIView()
         seperatorView.backgroundColor = tableViewSeperatorColor
         addSubview(seperatorView)
@@ -259,7 +261,7 @@ open class DropdownMenu: UIView {
         NSLayoutConstraint.activate([NSLayoutConstraint.init(item: seperatorView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 0.5)])
     }
     
-    fileprivate func setupNavigationBarCoverView(on view: UIView) {
+    private func setupNavigationBarCoverView(on view: UIView) {
         barCoverView = UIView()
         barCoverView?.backgroundColor = UIColor.clear
         view.addSubview(barCoverView!)
@@ -273,7 +275,7 @@ open class DropdownMenu: UIView {
         barCoverView?.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(hideMenu)))
     }
     
-    fileprivate func tableviewHeight() -> CGFloat {
+    private func tableviewHeight() -> CGFloat {
         var height: CGFloat = 0
         sections.enumerated().forEach {
             if displaySectionHeader {
diff --git a/DropdownMenu/SectionHeader.swift b/DropdownMenu/SectionHeader.swift
index ca39a21..f8fda7f 100644
--- a/DropdownMenu/SectionHeader.swift
+++ b/DropdownMenu/SectionHeader.swift
@@ -7,7 +7,12 @@
 //
 
 open class SectionHeader: UIView {
-    var titleLabel: UILabel!
+    var titleLabel: UILabel =  {
+        let titleLabel = UILabel()
+        titleLabel.translatesAutoresizingMaskIntoConstraints = false
+        return titleLabel
+    }()
+    
     var style: SectionHeaderStyle = SectionHeaderStyle()
 
     convenience init(style: SectionHeaderStyle) {
@@ -25,8 +30,6 @@ open class SectionHeader: UIView {
     }
 
     func commonInit() {
-        titleLabel = UILabel()
-        titleLabel.translatesAutoresizingMaskIntoConstraints = false
         titleLabel.font = style.font
         titleLabel.textColor = style.textColor
         backgroundColor = style.backgroundColor
diff --git a/DropdownMenuDemo/DropdownMenuDemo.xcodeproj/project.pbxproj b/DropdownMenuDemo/DropdownMenuDemo.xcodeproj/project.pbxproj
index ecb07d9..586e282 100644
--- a/DropdownMenuDemo/DropdownMenuDemo.xcodeproj/project.pbxproj
+++ b/DropdownMenuDemo/DropdownMenuDemo.xcodeproj/project.pbxproj
@@ -224,25 +224,25 @@
 					ACE6DB8E1CF741F6005C6667 = {
 						CreatedOnToolsVersion = 7.3.1;
 						DevelopmentTeam = ZDUX4TJC7F;
-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1020;
 					};
 					ACE6DBA21CF741F6005C6667 = {
 						CreatedOnToolsVersion = 7.3.1;
 						DevelopmentTeam = 7NLBE99QC4;
-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1020;
 						TestTargetID = ACE6DB8E1CF741F6005C6667;
 					};
 					ACE6DBAD1CF741F6005C6667 = {
 						CreatedOnToolsVersion = 7.3.1;
 						DevelopmentTeam = 7NLBE99QC4;
-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1020;
 						TestTargetID = ACE6DB8E1CF741F6005C6667;
 					};
 				};
 			};
 			buildConfigurationList = ACE6DB8A1CF741F6005C6667 /* Build configuration list for PBXProject "DropdownMenuDemo" */;
 			compatibilityVersion = "Xcode 3.2";
-			developmentRegion = English;
+			developmentRegion = en;
 			hasScannedForEncodings = 0;
 			knownRegions = (
 				en,
@@ -400,7 +400,7 @@
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Debug;
@@ -450,7 +450,7 @@
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				VALIDATE_PRODUCT = YES;
 			};
@@ -466,7 +466,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.teambition.DropdownMenu2;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
@@ -480,7 +480,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.teambition.DropdownMenu2;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Release;
 		};
@@ -493,7 +493,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.teambition.DropdownMenuDemoTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/DropdownMenuDemo.app/DropdownMenuDemo";
 			};
 			name = Debug;
@@ -507,7 +507,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.teambition.DropdownMenuDemoTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/DropdownMenuDemo.app/DropdownMenuDemo";
 			};
 			name = Release;
@@ -520,7 +520,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.teambition.DropdownMenuDemoUITests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TEST_TARGET_NAME = DropdownMenuDemo;
 			};
 			name = Debug;
@@ -533,7 +533,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.teambition.DropdownMenuDemoUITests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TEST_TARGET_NAME = DropdownMenuDemo;
 			};
 			name = Release;
diff --git a/DropdownMenuTests/DropdownMenuTests.swift b/DropdownMenuTests/DropdownMenuTests.swift
index be0825e..bd89027 100644
--- a/DropdownMenuTests/DropdownMenuTests.swift
+++ b/DropdownMenuTests/DropdownMenuTests.swift
@@ -28,7 +28,7 @@ class DropdownMenuTests: XCTestCase {
     
     func testPerformanceExample() {
         // This is an example of a performance test case.
-        self.measureBlock {
+        self.measure {
             // Put the code you want to measure the time of here.
         }
     }