Improve network history interface when new requests are fired.

If the user is at the top of the table, we animate the insertion of the new row. If they have scrolled down the list, we maintain their relative position while adding the new row at the top without animation.

Classes/Network/FLEXNetworkHistoryTableViewController.m

@@ -69,8 +69,25 @@
 
 - (void)handleNewTransactionRecordedNotification:(NSNotification *)notification
 {
+    NSInteger existingRowCount = [self.networkTransactions count];
     [self updateTransactions];
-    [self.tableView reloadData];
+    NSInteger newRowCount = [self.networkTransactions count];
+    NSInteger addedRowCount = newRowCount - existingRowCount;
+
+    if (self.tableView.contentOffset.y <= 0.0 && addedRowCount > 0) {
+        // Insert animation if we're at the top.
+        NSMutableArray *indexPathsToReload = [NSMutableArray array];
+        for (NSInteger row = 0; row < addedRowCount; row++) {
+            [indexPathsToReload addObject:[NSIndexPath indexPathForRow:row inSection:0]];
+        }
+        [self.tableView insertRowsAtIndexPaths:indexPathsToReload withRowAnimation:UITableViewRowAnimationAutomatic];
+    } else {
+        // Maintain the user's position if they've scrolled down.
+        CGSize existingContentSize = self.tableView.contentSize;
+        [self.tableView reloadData];
+        CGFloat contentHeightChange = self.tableView.contentSize.height - existingContentSize.height;
+        self.tableView.contentOffset = CGPointMake(self.tableView.contentOffset.x, self.tableView.contentOffset.y + contentHeightChange);
+    }
 
     if (self.searchController.isActive) {
         [self updateSearchResultsWithSearchString:self.searchController.searchBar.text];
@@ -115,7 +132,9 @@
     FLEXNetworkTransactionTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kFLEXNetworkTransactionCellIdentifier forIndexPath:indexPath];
     cell.transaction = [self transactionAtIndexPath:indexPath inTableView:tableView];
 
-    if (indexPath.row % 2 == 0) {
+    // Since we insert from the top, assign background colors bottom up to keep them consistent for each transaction.
+    NSInteger totalRows = [tableView numberOfRowsInSection:indexPath.section];
+    if ((totalRows - indexPath.row) % 2 == 0) {
         cell.backgroundColor = [UIColor colorWithWhite:0.95 alpha:1.0];
     } else {
         cell.backgroundColor = [UIColor whiteColor];