diff --git a/README.md b/README.md
index 4c6b2aa..b284492 100644
--- a/README.md
+++ b/README.md
@@ -29,12 +29,30 @@ ZLSwipeableView *swipeableView = [[ZLSwipeableView alloc] initWithFrame:self.vie
 
 A `ZLSwipeableView` **must** have an object that implements `ZLSwipeableViewDelegate` to act as a data source. `ZLSwipeableView` will prefetch **three** views in advance to animate them.
 ~~~objective-c
+// required data source
 self.swipeableView.dataSource = self;
 
+#pragma mark - ZLSwipeableViewDataSource
 - (UIView *)nextViewForSwipeableView:(ZLSwipeableView *)swipeableView {
   return [[UIView alloc] init];
 }
 ~~~
+A `ZLSwipeableView` can have an optional delegate to receive callback.
+~~~objective-c
+// optional delegate
+self.swipeableView.delegate = self;
+
+#pragma mark - ZLSwipeableViewDelegate
+- (void)swipeableView: (ZLSwipeableView *)swipeableView didSwipeLeft:(UIView *)view {
+    NSLog(@"did swipe left");
+}
+- (void)swipeableView: (ZLSwipeableView *)swipeableView didSwipeRight:(UIView *)view {
+    NSLog(@"did swipe right");
+}
+- (void)swipeableView: (ZLSwipeableView *)swipeableView swipingView:(UIView *)view atLocation:(CGPoint)location {
+    NSLog(@"swiping at location: x %f, y%f", location.x, location.y);
+}
+~~~
 
 To swipe the top view programmatically:
 ~~~objective-c
diff --git a/ZLSwipeableViewDemo/ZLSwipeableViewDemo/Base.lproj/Main.storyboard b/ZLSwipeableViewDemo/ZLSwipeableViewDemo/Base.lproj/Main.storyboard
index bbd4ed5..f5f2eb9 100644
--- a/ZLSwipeableViewDemo/ZLSwipeableViewDemo/Base.lproj/Main.storyboard
+++ b/ZLSwipeableViewDemo/ZLSwipeableViewDemo/Base.lproj/Main.storyboard
@@ -27,7 +27,7 @@
                                 </connections>
                             </button>
                             <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="a3E-tF-qFC" userLabel="Reload">
-                                <rect key="frame" x="275.5" y="542" width="49" height="30"/>
+                                <rect key="frame" x="276" y="542" width="49" height="30"/>
                                 <state key="normal" title="Reload">
                                     <color key="titleShadowColor" white="0.5" alpha="1" colorSpace="calibratedWhite"/>
                                 </state>
@@ -44,7 +44,7 @@
                                     <action selector="swipeRightButtonAction:" destination="vXZ-lx-hvc" eventType="touchUpInside" id="tZK-sW-KTp"/>
                                 </connections>
                             </button>
-                            <view contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="C0K-0Y-C7k" userLabel="SwipeableContainerView" customClass="ZLSwipeableView">
+                            <view contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="C0K-0Y-C7k" userLabel="ZLSwipeableView" customClass="ZLSwipeableView">
                                 <rect key="frame" x="36" y="60" width="528" height="442"/>
                                 <color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
                             </view>
@@ -64,7 +64,7 @@
                         </constraints>
                     </view>
                     <connections>
-                        <outlet property="containerView" destination="C0K-0Y-C7k" id="rr8-xW-Wlk"/>
+                        <outlet property="swipeableView" destination="C0K-0Y-C7k" id="DWp-Pc-Kwe"/>
                     </connections>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="x5A-6p-PRh" sceneMemberID="firstResponder"/>
diff --git a/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ViewController.m b/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ViewController.m
index 4820f7e..7fff861 100644
--- a/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ViewController.m
+++ b/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ViewController.m
@@ -11,7 +11,7 @@
 #import "UIColor+FlatColors.h"
 #import "CardView.h"
 
-@interface ViewController () <ZLSwipeableViewDataSource>
+@interface ViewController () <ZLSwipeableViewDataSource, ZLSwipeableViewDelegate>
 @property (weak, nonatomic) IBOutlet ZLSwipeableView *swipeableView;
 
 @property (nonatomic, strong) NSArray *colors;
@@ -47,12 +47,17 @@ - (void)viewDidLoad {
                     @"Asbestos",
                     ];
 
-//    ZLSwipeableContainterView *container = [[ZLSwipeableContainterView alloc] initWithFrame:self.view.frame];
-//    [self.view addSubview:container];
+    // ZLSwipeableView *swipeableView = [[ZLSwipeableView alloc] initWithFrame:self.view.frame];
+    // [self.view addSubview:swipeableView];
     
     [self.swipeableView setNeedsLayout];
     [self.swipeableView layoutIfNeeded];
+    
+    // required data source
     self.swipeableView.dataSource = self;
+    
+    // optional delegate
+    self.swipeableView.delegate = self;
 }
 - (IBAction)swipeLeftButtonAction:(UIButton *)sender {
     [self.swipeableView swipeTopViewToLeft];
@@ -66,6 +71,18 @@ - (IBAction)reloadButtonAction:(UIButton *)sender {
     [self.swipeableView loadNextSwipeableViewsIfNeeded];
 }
 
+#pragma mark - ZLSwipeableViewDelegate
+- (void)swipeableView: (ZLSwipeableView *)swipeableView didSwipeLeft:(UIView *)view {
+    NSLog(@"did swipe left");
+}
+- (void)swipeableView: (ZLSwipeableView *)swipeableView didSwipeRight:(UIView *)view {
+    NSLog(@"did swipe right");
+}
+- (void)swipeableView: (ZLSwipeableView *)swipeableView swipingView:(UIView *)view atLocation:(CGPoint)location {
+    NSLog(@"swiping at location: x %f, y%f", location.x, location.y);
+}
+
+#pragma mark - ZLSwipeableViewDataSource
 - (UIView *)nextViewForSwipeableView:(ZLSwipeableView *)swipeableView {
     if (self.colorIndex<self.colors.count) {
         CardView *view = [[CardView alloc] initWithFrame:swipeableView.bounds];
@@ -75,6 +92,8 @@ - (UIView *)nextViewForSwipeableView:(ZLSwipeableView *)swipeableView {
     }
     return nil;
 }
+
+#pragma mark - ()
 - (UIColor *)colorForName:(NSString *)name
 {
     NSString *sanitizedName = [name stringByReplacingOccurrencesOfString:@" " withString:@""];
diff --git a/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ZLSwipeableView/ZLSwipeableView.h b/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ZLSwipeableView/ZLSwipeableView.h
index 7fc0580..65fd80b 100644
--- a/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ZLSwipeableView/ZLSwipeableView.h
+++ b/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ZLSwipeableView/ZLSwipeableView.h
@@ -11,12 +11,11 @@
 @class ZLSwipeableView;
 
 // Delegate
-@protocol ZLSwipeableContainerViewDelegate <NSObject>
+@protocol ZLSwipeableViewDelegate <NSObject>
 @optional
-
 - (void)swipeableView: (ZLSwipeableView *)swipeableView didSwipeLeft:(UIView *)view;
 - (void)swipeableView: (ZLSwipeableView *)swipeableView didSwipeRight:(UIView *)view;
-
+- (void)swipeableView: (ZLSwipeableView *)swipeableView swipingView:(UIView *)view atLocation:(CGPoint)location;
 @end
 
 
@@ -28,7 +27,7 @@
 
 @interface ZLSwipeableView : UIView
 @property (nonatomic, weak) id <ZLSwipeableViewDataSource> dataSource;
-@property (nonatomic, weak) id <ZLSwipeableContainerViewDelegate> delegate;
+@property (nonatomic, weak) id <ZLSwipeableViewDelegate> delegate;
 
 /**
  *  Enable this to rotate the views behind the top view. Default to YES.
diff --git a/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ZLSwipeableView/ZLSwipeableView.m b/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ZLSwipeableView/ZLSwipeableView.m
index 52be4bf..5ba6066 100644
--- a/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ZLSwipeableView/ZLSwipeableView.m
+++ b/ZLSwipeableViewDemo/ZLSwipeableViewDemo/ZLSwipeableView/ZLSwipeableView.m
@@ -30,7 +30,7 @@ @interface ZLSwipeableView () <UICollisionBehaviorDelegate, UIDynamicAnimatorDel
 @implementation ZLSwipeableView
 
 #pragma mark - Init
-- (id)initWithFrame:(CGRect)frame {
+- (instancetype)initWithFrame:(CGRect)frame {
     self = [super initWithFrame:frame];
     if (self) {
         [self setup];
@@ -55,8 +55,6 @@ -(void)setup {
     self.reuseCoverContainerView.userInteractionEnabled = false;
     [self addSubview:self.reuseCoverContainerView];
     
-    NSLog(@"self frame: %f %f %f %f", self.frame.origin.x, self.frame.origin.y, self.frame.size.width, self.frame.size.height);
-    NSLog(@"self bounds: %f %f %f %f", self.bounds.origin.x, self.bounds.origin.y, self.bounds.size.width, self.bounds.size.height);
     // Default properties
     self.isRotationEnabled = YES;
     self.rotationDegree = 1;
@@ -178,6 +176,9 @@ -(void)handlePan:(UIPanGestureRecognizer *)recognizer {
     
     if (recognizer.state == UIGestureRecognizerStateChanged) {
         self.anchorViewAttachmentBehavior.anchorPoint = location;
+        if (self.delegate && [self.delegate respondsToSelector:@selector(swipeableView:swipingView:atLocation:)]) {
+            [self.delegate swipeableView:self swipingView:swipeableView atLocation:location];
+        }
     }
     
     if(recognizer.state == UIGestureRecognizerStateEnded || recognizer.state == UIGestureRecognizerStateCancelled) {