fixed bug which caused scroll view content to scroll under navigation bar after popping view controller #117

Author: LS

TPKeyboardAvoiding/UIScrollView+TPKeyboardAvoidingAdditions.m

@@ -59,6 +59,10 @@ - (void)TPKeyboardAvoiding_keyboardWillShow:(NSNotification*)notification {
 
     UIView *firstResponder = [self TPKeyboardAvoiding_findFirstResponderBeneathView:self];
 
+    if (!firstResponder) {
+        return;
+    }
+    
     state.keyboardRect = keyboardRect;
     state.keyboardVisible = YES;
     state.priorInset = self.contentInset;