Use try function and Result.flatMap

Author: ikesyo

APIKit/APIKit.swift

@@ -94,20 +94,18 @@ public class API {
                     dispatch_async(mainQueue, { handler(.Failure(Box(error))) })
                     return
                 }
-                
-                switch self.responseBodyParser().parseData(data) {
-                case .Failure(let box):
-                    dispatch_async(mainQueue, { handler(failure(box.unbox)) })
-                    
-                case .Success(let box):
-                    if let response = request.responseFromObject(box.unbox) {
-                        dispatch_async(mainQueue, { handler(success(response)) })
+
+                let mappedResponse: Result<T.Response, NSError> = self.responseBodyParser().parseData(data).flatMap { rawResponse in
+                    if let response = request.responseFromObject(rawResponse) {
+                        return success(response)
                     } else {
                         let userInfo = [NSLocalizedDescriptionKey: "failed to create model object from raw object."]
                         let error = NSError(domain: APIKitErrorDomain, code: 0, userInfo: userInfo)
-                        dispatch_async(mainQueue, { handler(failure(error)) })
+                        return failure(error)
                     }
+
                 }
+                dispatch_async(mainQueue, { handler(mappedResponse) })
             }
 
             task.resume()            

APIKit/RequestBodyBuilder.swift

@@ -35,20 +35,14 @@ public enum RequestBodyBuilder {
                 result = failure(error)
                 break
             }
-            
-            var error: NSError?
-            if let data = NSJSONSerialization.dataWithJSONObject(object, options: writingOptions, error: &error) {
-                result = success(data)
-            } else {
-                result = failure(error!)
+
+            result = try { error in
+                return NSJSONSerialization.dataWithJSONObject(object, options: writingOptions, error: error)
             }
 
         case .URL(let encoding):
-            var error: NSError?
-            if let data = URLEncodedSerialization.dataFromObject(object, encoding: encoding, error: &error) {
-                result = success(data)
-            } else {
-                result = failure(error!)
+            result = try { error in
+                return URLEncodedSerialization.dataFromObject(object, encoding: encoding, error: error)
             }
 
         case .Custom(let (_, buildBodyFromObject)):

APIKit/ResponseBodyParser.swift

@@ -27,19 +27,13 @@ public enum ResponseBodyParser {
 
         switch self {
         case .JSON(let readingOptions):
-            var error: NSError?
-            if let object: AnyObject = NSJSONSerialization.JSONObjectWithData(data, options: readingOptions, error: &error) {
-                result = success(object)
-            } else {
-                result = failure(error!)
+            result = try { error in
+                return NSJSONSerialization.JSONObjectWithData(data, options: readingOptions, error: error)
             }
 
         case .URL(let encoding):
-            var error: NSError?
-            if let object: AnyObject = URLEncodedSerialization.objectFromData(data, encoding: encoding, error: &error) {
-                result = success(object)
-            } else {
-                result = failure(error!)
+            result = try { error in
+                return URLEncodedSerialization.objectFromData(data, encoding: encoding, error: error)
             }
 
         case .Custom(let (accept, parseData)):

APIKit/URLEncodedSerialization.swift

@@ -9,7 +9,7 @@ private func unescape(string: String) -> String {
 }
 
 public class URLEncodedSerialization {
-    public class func objectFromData(data: NSData, encoding: NSStringEncoding, inout error: NSError?) -> AnyObject? {
+    public class func objectFromData(data: NSData, encoding: NSStringEncoding, error: NSErrorPointer) -> AnyObject? {
         var dictionary: [String: AnyObject]?
 
         if let string = NSString(data: data, encoding: encoding) as? String {
@@ -26,19 +26,19 @@ public class URLEncodedSerialization {
 
         if dictionary == nil {
             let userInfo = [NSLocalizedDescriptionKey: "failed to decode urlencoded string."]
-            error = NSError(domain: APIKitErrorDomain, code: 0, userInfo: userInfo)
+            error.memory = NSError(domain: APIKitErrorDomain, code: 0, userInfo: userInfo)
         }
 
         return dictionary
     }
 
-    public class func dataFromObject(object: AnyObject, encoding: NSStringEncoding, inout error: NSError?) -> NSData? {
+    public class func dataFromObject(object: AnyObject, encoding: NSStringEncoding, error: NSErrorPointer) -> NSData? {
         let string = stringFromObject(object, encoding: encoding)
         let data = string.dataUsingEncoding(encoding, allowLossyConversion: false)
 
         if data == nil {
             let userInfo = [NSLocalizedDescriptionKey: "failed to decode urlencoded string."]
-            error = NSError(domain: APIKitErrorDomain, code: 0, userInfo: userInfo)
+            error.memory = NSError(domain: APIKitErrorDomain, code: 0, userInfo: userInfo)
         }
 
         return data