Sunday, July 13, 2014

RSNetworking: A networking library written in Swift

I was on vacation this past week and during some of my down time I started looking for a good networking library, like AFNetworking, written in Swift but I was unable to find anything mature enough to work with.  I know I could use any Objective-C library with Mix and Match but I wanted something I could use natively with Swift apps.  Therefore after all the searching I decided to write my own, it is called RSNetworking.  You can find the GitHub repository here:

RSNetworking is definitely not ready for a production app, after all I just started writing it a couple of nights ago but all good libraries have to start somewhere.  Right now the library consists on one simple file that contains the various functions.  As the library expands we will be breaking the functions into separate files but not sure how the library will expand yet.  I would welcome anyone that would like to contribute to this project or any suggestions that anyone may have.

Here is a list of the four functions that the library currently exposes:
* func dataFromURL(url: NSURL, completionHandler handler: RSNetworking.dataFromURLCompletionClosure):  Retrieves an NSData object from the URL passed in.  This is the main function and is used by the other three functions to retrieve an NSData object prior to converting it to the required format

* func stringFromURL(url: NSURL, completionHandler handler:  RSNetworking.stringFromURLCompletionClosure):  Retrieves an NSString object from the URL passed in.  This function uses the dataFromURL function to retrieve an NSData object and then converts it to an NSString object.

* func dictionaryFromJsonURL(url: NSURL, completionHandler handler:  RSNetworking.dictionaryFromURLCompletionClosure):  Retrieves an NSDictionary object from the URL passed in.  This function uses the dataFromURL function to retrieve an NSData object and then converts it to an NSDictionary object.  The data returned from the URL should be in JSON format for this function to work properly.

* func imageFromURL(url: NSURL, completionHandler handler:  RSNetworking.imageFromURLCompletionClosure):  Retrieves an UIImage object from the URL.  This function uses the dataFromURL function to retrieve an NSData object and then converts it to an UIImage object.

Lets look at how we would use the RSNetworking library.  Here is a sample of how we would call Apple’s iTunes search API:

var client = RSNetworking()
var testURL = NSURL.URLWithString("")

client.dictionaryFromJsonURL(testURL, completionHandler: {(response : NSURLResponse!, responseDictionary: NSDictionary!, error: NSError!) -> Void in

    if !error? {
      println("Response Dictionary: \(responseDictionary)")
  } else {
         println("Error : \(error)")

In this sample we begin by initializing RSNetworking and then we create a NSURL object with the URL of the service we wish to access.  We use the dictionaryFromJsonURL function to make our request to the iTunes search API.  When it returns the block is then executed.  Within the block we check for errors.  If there are no errors we log the dictionary however if there is an error we log the error.

You can download and try RSNetworking here:  You can also find the latest information on RSNetworking that thegithub URL.  I have included a sample project with the library that downloads and displays the data returned from the iTunes search above in a UITableView.  The sample also retrieves images and put them in an in-memory cache before displaying them in the UITableView.  Please try the library and let me know what you would like to see added.  Also, if you can, please contribute to RSNetworking.

See update 1 to library here

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