development: added begin and commit methods to Grid for transactional calculations

Sources/iOS/ControlView.swift

@@ -171,7 +171,7 @@ open class ControlView: View {
             let p = width - l - r - contentEdgeInsets.left - contentEdgeInsets.right
 			let columns = Int(p / gridFactor)
             
-            grid.deferred = true
+            grid.begin()
             grid.views.removeAll()
             grid.axis.columns = columns
             
@@ -209,8 +209,7 @@ open class ControlView: View {
                 contentView.grid.columns = columns - lc - rc
             }
             
-            grid.deferred = false
-            grid.reload()
+            grid.commit()
         }
     }
     

Sources/iOS/Grid.swift

@@ -197,6 +197,17 @@ public class Grid {
         axis = GridAxis(grid: self)
     }
     
+    /// Begins a deferred block.
+    public func begin() {
+        deferred = true
+    }
+    
+    /// Completes a deferred block.
+    public func commit() {
+        deferred = false
+        reload()
+    }
+    
     /// Reload the button layout.
     public func reload() {
         guard !deferred else {

Sources/iOS/NavigationBar.swift

@@ -204,7 +204,7 @@ open class NavigationBar: UINavigationBar {
             let p = width - l - r - contentEdgeInsets.left - contentEdgeInsets.right
             let columns = Int(p / gridFactor)
             
-            item.titleView!.grid.deferred = true
+            item.titleView!.grid.begin()
             item.titleView!.grid.views.removeAll()
             item.titleView!.grid.axis.columns = columns
             
@@ -244,8 +244,7 @@ open class NavigationBar: UINavigationBar {
             
             item.titleView!.grid.interimSpace = interimSpace
             item.titleView!.grid.contentEdgeInsets = contentEdgeInsets
-            item.titleView!.grid.deferred = false
-            item.titleView!.grid.reload()
+            item.titleView!.grid.commit()
             
             // contentView alignment.
             if nil != item.title && "" != item.title {