From d97164f7284d55b3fb43d6c84c8256af3ee2cc5f Mon Sep 17 00:00:00 2001
From: Mazyad Alabduljaleel <mazjaleel@gmail.com>
Date: Tue, 15 Jul 2014 14:18:17 +0400
Subject: [PATCH] [FIX]: don't handle the scrolling if the content size of the
 scroll view is insufficiently long. #12

---
 TLYShyNavBar/TLYShyNavBarManager.m  | 11 ++++++++++-
 TLYShyNavBar/TLYShyViewController.h |  2 ++
 TLYShyNavBar/TLYShyViewController.m | 11 +++++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/TLYShyNavBar/TLYShyNavBarManager.m b/TLYShyNavBar/TLYShyNavBarManager.m
index 3f54c07..518d8c0 100644
--- a/TLYShyNavBar/TLYShyNavBarManager.m
+++ b/TLYShyNavBar/TLYShyNavBarManager.m
@@ -152,9 +152,18 @@ static inline CGFloat AACStatusBarHeight()
 
 #pragma mark - Private methods
 
+- (BOOL)_shouldHandleScrolling
+{
+    CGRect scrollFrame = UIEdgeInsetsInsetRect(self.scrollView.bounds, self.scrollView.contentInset);
+    CGFloat scrollableAmount = self.scrollView.contentSize.height - CGRectGetHeight(scrollFrame);
+    BOOL scrollViewIsSuffecientlyLong = (scrollableAmount > self.navBarController.totalHeight);
+    
+    return (self.isViewControllerVisible && scrollViewIsSuffecientlyLong);
+}
+
 - (void)_handleScrolling
 {
-    if (!self.isViewControllerVisible)
+    if (![self _shouldHandleScrolling])
     {
         return;
     }
diff --git a/TLYShyNavBar/TLYShyViewController.h b/TLYShyNavBar/TLYShyViewController.h
index 5d0bc71..1a7451d 100644
--- a/TLYShyNavBar/TLYShyViewController.h
+++ b/TLYShyNavBar/TLYShyViewController.h
@@ -35,6 +35,8 @@ typedef CGFloat(^TLYShyViewControllerContractionAmountBlock)(UIView *view);
 @property (nonatomic) BOOL hidesSubviews;
 @property (nonatomic) BOOL hidesAfterContraction;
 
+@property (nonatomic, readonly) CGFloat totalHeight;
+
 - (CGFloat)updateYOffset:(CGFloat)deltaY;
 
 - (CGFloat)snap:(BOOL)contract;
diff --git a/TLYShyNavBar/TLYShyViewController.m b/TLYShyNavBar/TLYShyViewController.m
index 9616df9..b09f610 100644
--- a/TLYShyNavBar/TLYShyViewController.m
+++ b/TLYShyNavBar/TLYShyViewController.m
@@ -24,6 +24,8 @@ const CGFloat contractionVelocity = 300.f;
 
 @implementation TLYShyViewController
 
+#pragma mark - Properties
+
 // convenience
 - (CGPoint)expandedCenterValue
 {
@@ -50,6 +52,13 @@ const CGFloat contractionVelocity = 300.f;
     return fabs(self.view.center.y - self.expandedCenterValue.y) < FLT_EPSILON;
 }
 
+- (CGFloat)totalHeight
+{
+    return self.child.totalHeight + (self.expandedCenterValue.y - self.contractedCenterValue.y);
+}
+
+#pragma mark - Private methods
+
 // This method is courtesy of GTScrollNavigationBar
 // https://github.com/luugiathuy/GTScrollNavigationBar
 - (void)_updateSubviewsToAlpha:(CGFloat)alpha
@@ -66,6 +75,8 @@ const CGFloat contractionVelocity = 300.f;
     }
 }
 
+#pragma mark - Public methods
+
 - (CGFloat)updateYOffset:(CGFloat)deltaY
 {
     if (self.child && deltaY < 0)