added mechanism to track transaction sources

Sources/CSUnsafeDataTransaction.swift

@@ -46,21 +46,25 @@ public final class CSUnsafeDataTransaction: CSBaseDataTransaction, CoreStoreObje
     @objc
     public func commitWithSuccess(_ success: (() -> Void)?, _ failure: ((CSError) -> Void)?) {
         
-        self.bridgeToSwift.context.saveAsynchronouslyWithCompletion { (_, error) in
-            
-            defer {
+        let transaction = self.bridgeToSwift
+        transaction.context.saveAsynchronously(
+            sourceIdentifier: transaction.sourceIdentifier,
+            completion: { (_, error) in
                 
-                withExtendedLifetime(self, {})
+                defer {
+                    
+                    withExtendedLifetime(self, {})
+                }
+                if let error = error {
+                    
+                    failure?(error.bridgeToObjectiveC)
+                }
+                else {
+                    
+                    success?()
+                }
             }
-            if let error = error {
-                
-                failure?(error.bridgeToObjectiveC)
-            }
-            else {
-                
-                success?()
-            }
-        }
+        )
     }
     
     /**
@@ -74,7 +78,11 @@ public final class CSUnsafeDataTransaction: CSBaseDataTransaction, CoreStoreObje
         
         return bridge(error) {
             
-            if case (_, let error?) = self.bridgeToSwift.context.saveSynchronously(waitForMerge: true) {
+            let transaction = self.bridgeToSwift
+            if case (_, let error?) = transaction.context.saveSynchronously(
+                waitForMerge: true,
+                sourceIdentifier: transaction.sourceIdentifier
+            ) {
                 
                 throw error
             }
@@ -152,15 +160,61 @@ public final class CSUnsafeDataTransaction: CSBaseDataTransaction, CoreStoreObje
     /**
      Begins a child transaction where `NSManagedObject` creates, updates, and deletes can be made. This is useful for making temporary changes, such as partially filled forms.
      
-     - prameter supportsUndo: `-undo`, `-redo`, and `-rollback` methods are only available when this parameter is `YES`, otherwise those method will raise an exception. Note that turning on Undo support may heavily impact performance especially on iOS or watchOS where memory is limited.
+     To support "undo" methods such as `-undo`, `-redo`, and `-rollback`, use the `-beginSafeWithSupportsUndo:` method passing `YES` to the argument. Without "undo" support, calling those methods will raise an exception.
+     - parameter sourceIdentifier: an optional value that identifies the source of this transaction. This identifier will be passed to the change notifications and callers can use it for custom handling that depends on the source.
      - returns: a `CSUnsafeDataTransaction` instance where creates, updates, and deletes can be made.
      */
     @objc
-    public func beginUnsafeWithSupportsUndo(_ supportsUndo: Bool) -> CSUnsafeDataTransaction {
+    public func beginUnsafeWithSourceIdentifier(
+        _ sourceIdentifier: Any?
+    ) -> CSUnsafeDataTransaction {
         
         return bridge {
             
-            self.bridgeToSwift.beginUnsafe(supportsUndo: supportsUndo)
+            self.bridgeToSwift.beginUnsafe(
+                sourceIdentifier: sourceIdentifier
+            )
+        }
+    }
+    
+    /**
+     Begins a child transaction where `NSManagedObject` creates, updates, and deletes can be made. This is useful for making temporary changes, such as partially filled forms.
+     
+     - parameter supportsUndo: `-undo`, `-redo`, and `-rollback` methods are only available when this parameter is `YES`, otherwise those method will raise an exception. Note that turning on Undo support may heavily impact performance especially on iOS or watchOS where memory is limited.
+     - returns: a `CSUnsafeDataTransaction` instance where creates, updates, and deletes can be made.
+     */
+    @objc
+    public func beginUnsafeWithSupportsUndo(
+        _ supportsUndo: Bool
+    ) -> CSUnsafeDataTransaction {
+        
+        return bridge {
+            
+            self.bridgeToSwift.beginUnsafe(
+                supportsUndo: supportsUndo
+            )
+        }
+    }
+    
+    /**
+     Begins a child transaction where `NSManagedObject` creates, updates, and deletes can be made. This is useful for making temporary changes, such as partially filled forms.
+     
+     - parameter supportsUndo: `-undo`, `-redo`, and `-rollback` methods are only available when this parameter is `YES`, otherwise those method will raise an exception. Note that turning on Undo support may heavily impact performance especially on iOS or watchOS where memory is limited.
+     - parameter sourceIdentifier: an optional value that identifies the source of this transaction. This identifier will be passed to the change notifications and callers can use it for custom handling that depends on the source.
+     - returns: a `CSUnsafeDataTransaction` instance where creates, updates, and deletes can be made.
+     */
+    @objc
+    public func beginUnsafeWithSupportsUndo(
+        _ supportsUndo: Bool,
+        sourceIdentifier: Any?
+    ) -> CSUnsafeDataTransaction {
+        
+        return bridge {
+            
+            self.bridgeToSwift.beginUnsafe(
+                supportsUndo: supportsUndo,
+                sourceIdentifier: sourceIdentifier
+            )
         }
     }