Extract controller logic into models

Tweets/app/data_parser.rb

@@ -0,0 +1,10 @@
+class DataParser
+  def self.parse(url)
+    error_ptr = Pointer.new(:object)
+    data = NSData.alloc.initWithContentsOfURL(NSURL.URLWithString(url), options:NSDataReadingUncached, error:error_ptr)
+    unless data
+      raise error_ptr[0]
+    end
+    data
+  end
+end

Tweets/app/json_parser.rb

@@ -0,0 +1,12 @@
+class JSONParser
+  def self.parse_from_url(url)
+    data = DataParser.parse(url)
+
+    error_ptr = Pointer.new(:object)
+    json = NSJSONSerialization.JSONObjectWithData(data, options:0, error:error_ptr)
+    unless json
+      raise error_ptr[0]
+    end
+    json
+  end
+end

Tweets/app/tweets_controller.rb

@@ -18,16 +18,11 @@ def searchBarSearchButtonClicked(searchBar)
 
     @tweets.clear
     Dispatch::Queue.concurrent.async do 
-      error_ptr = Pointer.new(:object)
-      data = NSData.alloc.initWithContentsOfURL(NSURL.URLWithString(url), options:NSDataReadingUncached, error:error_ptr)
-      unless data
-        presentError error_ptr[0]
-        return
-      end
-      json = NSJSONSerialization.JSONObjectWithData(data, options:0, error:error_ptr)
-      unless json
-        presentError error_ptr[0]
-        return
+      json = nil
+      begin
+        json = JSONParser.parse_from_url(url)
+      rescue RuntimeError => e
+        presentError e.message
       end
 
       new_tweets = []