Fixes default datasources implementation. ReactiveX#825

Author: kzaher

RxCocoa/Common/DelegateProxyType.swift

@@ -178,14 +178,14 @@ extension DelegateProxyType {
         let maybeProxy = Self.assignedProxyFor(object) as? Self
 
         let proxy: Self
-        if maybeProxy == nil {
+        if let existingProxy = maybeProxy {
+            proxy = existingProxy
+        }
+        else {
             proxy = Self.createProxyForObject(object) as! Self
             Self.assignProxy(proxy, toObject: object)
             assert(Self.assignedProxyFor(object) === proxy)
         }
-        else {
-            proxy = maybeProxy!
-        }
 
         let currentDelegate: AnyObject? = Self.currentDelegateFor(object)
 

RxCocoa/iOS/Proxies/RxCollectionViewDataSourceProxy.swift

@@ -19,6 +19,11 @@ let collectionViewDataSourceNotSet = CollectionViewDataSourceNotSet()
 class CollectionViewDataSourceNotSet
     : NSObject
     , UICollectionViewDataSource {
+
+    func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
+        return 0
+    }
+
     func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
         rxAbstractMethodWithMessage(dataSourceNotSet)
     }

RxCocoa/iOS/Proxies/RxTableViewDataSourceProxy.swift

@@ -20,7 +20,7 @@ class TableViewDataSourceNotSet
     : NSObject
     , UITableViewDataSource {
     func numberOfSectionsInTableView(tableView: UITableView) -> Int {
-        rxAbstractMethodWithMessage(dataSourceNotSet)
+        return 0
     }
 
     func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
@@ -63,7 +63,7 @@ public class RxTableViewDataSourceProxy
     Required delegate method implementation.
     */
     public func numberOfSectionsInTableView(tableView: UITableView) -> Int {
-        return (_requiredMethodsDataSource ?? tableViewDataSourceNotSet).numberOfSectionsInTableView?(tableView) ?? 1
+        return (_requiredMethodsDataSource ?? tableViewDataSourceNotSet).numberOfSectionsInTableView?(tableView) ?? 0
     }
 
     /**