gonzalezreal · February 8, 2017 16:22 · Apr 8, 2015 · Apr 7, 2015
diff --git a/ValueTransformer.swift b/ValueTransformer.swift
@@ -50,7 +50,7 @@ public extension NSValueTransformer {
      */
     class func setValueTransformerWithName<T, U>(name: String, transform: (T) -> (U?)) {
         let transformer = ValueTransformer { value in
-            return flatMap(value as? T) {
+            return (value as? T).flatMap {
                 transform($0) as? AnyObject
             }
         }
@@ -67,11 +67,11 @@ public extension NSValueTransformer {
      */
     class func setValueTransformerWithName<T, U>(name: String, transform: (T) -> (U?), reverseTransform: (U) -> (T?)) {
         let transformer = ReversibleValueTransformer(transform: { value in
-            return flatMap(value as? T) {
+            return (value as? T).flatMap {
                 transform($0) as? AnyObject
             }
         }, reverseTransform: { value in
-            return flatMap(value as? U) {
+            return (value as? U).flatMap {
                 reverseTransform($0) as? AnyObject
             }
         })

diff --git a/ValueTransformer.swift b/ValueTransformer.swift
@@ -0,0 +1,81 @@
+import Foundation
+
+private class ValueTransformer: NSValueTransformer {
+    let transform: (AnyObject?) -> (AnyObject?)
+
+    init(transform: (AnyObject?) -> (AnyObject?)) {
+        self.transform = transform
+    }
+
+    // MARK: NSValueTransformer
+
+    override class func allowsReverseTransformation() -> Bool {
+        return false;
+    }
+
+    override class func transformedValueClass() -> AnyClass {
+        return NSObject.self
+    }
+
+    override func transformedValue(value: AnyObject?) -> AnyObject? {
+        return transform(value)
+    }
+}
+
+private class ReversibleValueTransformer: ValueTransformer {
+    let reverseTransform: (AnyObject?) -> (AnyObject?)
+
+    init(transform: (AnyObject?) -> (AnyObject?), reverseTransform: (AnyObject?) -> (AnyObject?)) {
+        self.reverseTransform = reverseTransform
+        super.init(transform: transform)
+    }
+
+    // MARK: NSValueTransformer
+
+    override class func allowsReverseTransformation() -> Bool {
+        return true;
+    }
+
+    override func reverseTransformedValue(value: AnyObject?) -> AnyObject? {
+        return reverseTransform(value)
+    }
+}
+
+public extension NSValueTransformer {
+    /**
+     Registers a value transformer with a given name and transform function.
+
+     :param: name The name of the transformer.
+     :param: transform The function that performs the transformation.
+     */
+    class func setValueTransformerWithName<T, U>(name: String, transform: (T) -> (U?)) {
+        let transformer = ValueTransformer { value in
+            return flatMap(value as? T) {
+                transform($0) as? AnyObject
+            }
+        }
+
+        self.setValueTransformer(transformer, forName: name)
+    }
+
+    /**
+     Registers a reversible value transformer with a given name and transform functions.
+
+     :param: name The name of the transformer.
+     :param: transform The function that performs the forward transformation.
+     :param: reverseTransform The function that performs the reverse transformation.
+     */
+    class func setValueTransformerWithName<T, U>(name: String, transform: (T) -> (U?), reverseTransform: (U) -> (T?)) {
+        let transformer = ReversibleValueTransformer(transform: { value in
+            return flatMap(value as? T) {
+                transform($0) as? AnyObject
+            }
+        }, reverseTransform: { value in
+            return flatMap(value as? U) {
+                reverseTransform($0) as? AnyObject
+            }
+        })
+
+        self.setValueTransformer(transformer, forName: name)
+    }
+}
diff --git a/usage.swift b/usage.swift
@@ -0,0 +1,9 @@
+func stringToInt(value: String) -> Int? {
+    return value.toInt()
+}
+
+func intToString(value: Int) -> String? {
+    return "\(value)"
+}
+
+NSValueTransformer.setValueTransformerWithName("StringToInt", transform: stringToInt, reverseTransform: intToString)