Added elastic boolean to let the user pan the center view controller past the edge

MFSideMenu/MFSideMenuContainerViewController.h

@@ -61,6 +61,8 @@ typedef enum {
 @property (nonatomic, assign) BOOL menuSlideAnimationEnabled;
 @property (nonatomic, assign) CGFloat menuSlideAnimationFactor; // higher = less menu movement on animation
 
+// allow elastic panning when the side menu is in the open state
+@property (nonatomic, assign) BOOL elastic;
 
 - (void)toggleLeftSideMenuCompletion:(void (^)(void))completion;
 - (void)toggleRightSideMenuCompletion:(void (^)(void))completion;

MFSideMenu/MFSideMenuContainerViewController.m

@@ -45,6 +45,7 @@ @implementation MFSideMenuContainerViewController
 @synthesize menuAnimationDefaultDuration;
 @synthesize menuAnimationMaxDuration;
 @synthesize shadow;
+@synthesize elastic;
 
 
 #pragma mark -
@@ -85,6 +86,7 @@ - (void)setDefaultSettings {
     self.menuAnimationMaxDuration = 0.4f;
     self.panMode = MFSideMenuPanModeDefault;
     self.viewHasAppeared = NO;
+    self.elastic = NO;
 }
 
 - (void)setupMenuContainerView {
@@ -381,7 +383,7 @@ - (void)sendStateEventNotification:(MFSideMenuStateEvent)event {
 #pragma mark -
 #pragma mark - Side Menu Positioning
 
-- (void) setLeftSideMenuFrameToClosedPosition {
+- (void)setLeftSideMenuFrameToClosedPosition {
     if(!self.leftMenuViewController) return;
     CGRect leftFrame = [self.leftMenuViewController view].frame;
     leftFrame.size.width = self.leftMenuWidth;
@@ -391,7 +393,7 @@ - (void) setLeftSideMenuFrameToClosedPosition {
     [self.leftMenuViewController view].autoresizingMask = UIViewAutoresizingFlexibleRightMargin|UIViewAutoresizingFlexibleHeight;
 }
 
-- (void) setRightSideMenuFrameToClosedPosition {
+- (void)setRightSideMenuFrameToClosedPosition {
     if(!self.rightMenuViewController) return;
     CGRect rightFrame = [self.rightMenuViewController view].frame;
     rightFrame.size.width = self.rightMenuWidth;
@@ -406,7 +408,12 @@ - (void)alignLeftMenuControllerWithCenterViewController {
     CGRect leftMenuFrame = [self.leftMenuViewController view].frame;
     leftMenuFrame.size.width = _leftMenuWidth;
 
+    // prevent the slide from left animation from going past the menuWidth
     CGFloat xOffset = [self.centerViewController view].frame.origin.x;
+    if (xOffset > self.leftMenuWidth) {
+        return;
+    }
+
     CGFloat xPositionDivider = (self.menuSlideAnimationEnabled) ? self.menuSlideAnimationFactor : 1.0;
     leftMenuFrame.origin.x = xOffset / xPositionDivider - _leftMenuWidth / xPositionDivider;
 
@@ -417,11 +424,16 @@ - (void)alignRightMenuControllerWithCenterViewController {
     CGRect rightMenuFrame = [self.rightMenuViewController view].frame;
     rightMenuFrame.size.width = _rightMenuWidth;
 
+    // prevent the slide from right animation from going past the menuWidth
     CGFloat xOffset = [self.centerViewController view].frame.origin.x;
+    if (xOffset < -1*self.rightMenuWidth) {
+        return;
+    }
+
     CGFloat xPositionDivider = (self.menuSlideAnimationEnabled) ? self.menuSlideAnimationFactor : 1.0;
     rightMenuFrame.origin.x = self.menuContainerView.frame.size.width - _rightMenuWidth
-        + xOffset / xPositionDivider
-        + _rightMenuWidth / xPositionDivider;
+    + xOffset / xPositionDivider
+    + _rightMenuWidth / xPositionDivider;
 
     [self.rightMenuViewController view].frame = rightMenuFrame;
 }
@@ -483,11 +495,11 @@ - (void)setRightMenuWidth:(CGFloat)rightMenuWidth animated:(BOOL)animated {
 #pragma mark -
 #pragma mark - MFSideMenuPanMode
 
-- (BOOL) centerViewControllerPanEnabled {
+- (BOOL)centerViewControllerPanEnabled {
     return ((self.panMode & MFSideMenuPanModeCenterViewController) == MFSideMenuPanModeCenterViewController);
 }
 
-- (BOOL) sideMenuPanEnabled {
+- (BOOL)sideMenuPanEnabled {
     return ((self.panMode & MFSideMenuPanModeSideMenu) == MFSideMenuPanModeSideMenu);
 }
 
@@ -504,7 +516,7 @@ - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceive
             return [self centerViewControllerPanEnabled];
 
         if([gestureRecognizer.view isEqual:self.menuContainerView])
-           return [self sideMenuPanEnabled];
+            return [self sideMenuPanEnabled];
 
         // pan gesture is attached to a custom view
         return YES;
@@ -528,7 +540,7 @@ - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
 
 // this method handles any pan event
 // and sets the navigation controller's frame as needed
-- (void) handlePan:(UIPanGestureRecognizer *)recognizer {
+- (void)handlePan:(UIPanGestureRecognizer *)recognizer {
     UIView *view = [self.centerViewController view];
 
 	if(recognizer.state == UIGestureRecognizerStateBegan) {
@@ -553,10 +565,10 @@ - (void) handlePan:(UIPanGestureRecognizer *)recognizer {
         }
     }
 
-    if((self.menuState == MFSideMenuStateRightMenuOpen && self.panDirection == MFSideMenuPanDirectionLeft)
-       || (self.menuState == MFSideMenuStateLeftMenuOpen && self.panDirection == MFSideMenuPanDirectionRight)) {
+    if (!self.elastic &&
+        (self.menuState == MFSideMenuStateLeftMenuOpen && self.panDirection == MFSideMenuPanDirectionRight) &&
+        (self.menuState == MFSideMenuStateRightMenuOpen && self.panDirection == MFSideMenuPanDirectionLeft)) {
         self.panDirection = MFSideMenuPanDirectionNone;
-        return;
     }
 
     if(self.panDirection == MFSideMenuPanDirectionLeft) {
@@ -566,7 +578,7 @@ - (void) handlePan:(UIPanGestureRecognizer *)recognizer {
     }
 }
 
-- (void) handleRightPan:(UIPanGestureRecognizer *)recognizer {
+- (void)handleRightPan:(UIPanGestureRecognizer *)recognizer {
     if(!self.leftMenuViewController && self.menuState == MFSideMenuStateClosed) return;
 
     UIView *view = [self.centerViewController view];
@@ -576,8 +588,12 @@ - (void) handleRightPan:(UIPanGestureRecognizer *)recognizer {
     translatedPoint = CGPointMake(adjustedOrigin.x + translatedPoint.x,
                                   adjustedOrigin.y + translatedPoint.y);
 
-    translatedPoint.x = MAX(translatedPoint.x, -1*self.rightMenuWidth);
-    translatedPoint.x = MIN(translatedPoint.x, self.leftMenuWidth);
+    // Allow user to pan past the edge if elastic is YES
+    if (!self.elastic) {
+        translatedPoint.x = MAX(translatedPoint.x, -1*self.rightMenuWidth);
+        translatedPoint.x = MIN(translatedPoint.x, self.leftMenuWidth);
+    }
+
     if(self.menuState == MFSideMenuStateRightMenuOpen) {
         // menu is already open, the most the user can do is close it in this gesture
         translatedPoint.x = MIN(translatedPoint.x, 0);
@@ -591,7 +607,7 @@ - (void) handleRightPan:(UIPanGestureRecognizer *)recognizer {
         CGFloat finalX = translatedPoint.x + (.35*velocity.x);
         CGFloat viewWidth = view.frame.size.width;
 
-        if(self.menuState == MFSideMenuStateClosed) {
+        if (self.menuState == MFSideMenuStateClosed) {
             BOOL showMenu = (finalX > viewWidth/2) || (finalX > self.leftMenuWidth/2);
             if(showMenu) {
                 self.panGestureVelocity = velocity.x;
@@ -603,9 +619,17 @@ - (void) handleRightPan:(UIPanGestureRecognizer *)recognizer {
         } else {
             BOOL hideMenu = (finalX > adjustedOrigin.x);
             if(hideMenu) {
+                if (self.elastic && self.menuState == MFSideMenuStateLeftMenuOpen) {
+                    [self setMenuState:MFSideMenuStateLeftMenuOpen];
+                    return;
+                }
                 self.panGestureVelocity = velocity.x;
                 [self setMenuState:MFSideMenuStateClosed];
             } else {
+                if (self.elastic && self.menuState == MFSideMenuStateLeftMenuOpen) {
+                    [self setMenuState:MFSideMenuStateClosed];
+                    return;
+                }
                 self.panGestureVelocity = 0;
                 [self setCenterViewControllerOffset:adjustedOrigin.x animated:YES completion:nil];
             }
@@ -617,7 +641,7 @@ - (void) handleRightPan:(UIPanGestureRecognizer *)recognizer {
     }
 }
 
-- (void) handleLeftPan:(UIPanGestureRecognizer *)recognizer {
+- (void)handleLeftPan:(UIPanGestureRecognizer *)recognizer {
     if(!self.rightMenuViewController && self.menuState == MFSideMenuStateClosed) return;
 
     UIView *view = [self.centerViewController view];
@@ -627,8 +651,12 @@ - (void) handleLeftPan:(UIPanGestureRecognizer *)recognizer {
     translatedPoint = CGPointMake(adjustedOrigin.x + translatedPoint.x,
                                   adjustedOrigin.y + translatedPoint.y);
 
-    translatedPoint.x = MAX(translatedPoint.x, -1*self.rightMenuWidth);
-    translatedPoint.x = MIN(translatedPoint.x, self.leftMenuWidth);
+    // allow user to pan past the edge if elastic is enabled
+    if (!self.elastic) {
+        translatedPoint.x = MAX(translatedPoint.x, -1*self.rightMenuWidth);
+        translatedPoint.x = MIN(translatedPoint.x, self.leftMenuWidth);
+    }
+
     if(self.menuState == MFSideMenuStateLeftMenuOpen) {
         // don't let the pan go less than 0 if the menu is already open
         translatedPoint.x = MAX(translatedPoint.x, 0);
@@ -637,8 +665,6 @@ - (void) handleLeftPan:(UIPanGestureRecognizer *)recognizer {
         translatedPoint.x = MIN(translatedPoint.x, 0);
     }
 
-    [self setCenterViewControllerOffset:translatedPoint.x];
-
 	if(recognizer.state == UIGestureRecognizerStateEnded) {
         CGPoint velocity = [recognizer velocityInView:view];
         CGFloat finalX = translatedPoint.x + (.35*velocity.x);
@@ -656,9 +682,17 @@ - (void) handleLeftPan:(UIPanGestureRecognizer *)recognizer {
         } else {
             BOOL hideMenu = (finalX < adjustedOrigin.x);
             if(hideMenu) {
+                if (self.elastic && self.menuState == MFSideMenuStateRightMenuOpen) {
+                    [self setMenuState:MFSideMenuStateRightMenuOpen];
+                    return;
+                }
                 self.panGestureVelocity = velocity.x;
                 [self setMenuState:MFSideMenuStateClosed];
             } else {
+                if (self.elastic && self.menuState == MFSideMenuStateRightMenuOpen) {
+                    [self setMenuState:MFSideMenuStateClosed];
+                    return;
+                }
                 self.panGestureVelocity = 0;
                 [self setCenterViewControllerOffset:adjustedOrigin.x animated:YES completion:nil];
             }
@@ -743,6 +777,7 @@ - (CGFloat)animationDurationFromStartPosition:(CGFloat)startPosition toEndPositi
     if(ABS(self.panGestureVelocity) > 1.0) {
         // try to continue the animation at the speed the user was swiping
         duration = animationPositionDelta / ABS(self.panGestureVelocity);
+        self.panGestureVelocity = 0.0;
     } else {
         // no swipe was used, user tapped the bar button item
         // TODO: full animation duration hard to calculate with two menu widths

README.mdown

@@ -81,6 +81,14 @@ You can add panning to any view like so:
 [panView addGestureRecognizer:[self.menuContainerViewController panGestureRecognizer];
 ```
 
+###Elasticity
+
+You can enable elasticity which allows the user to pan beyond the edges of the screen for a more natural feel. By default, this feature is disabled.
+
+```objective-c
+self.menuContainerViewController.elastic = YES;
+```
+
 ###Listening for Menu Events
 
 You can listen for menu state event changes (i.e. menu will open, menu did open, etc.). See MFSideMenuContainerViewController.h for the different types of events.