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Stub your network requests easily! Test your apps with fake network data and custom response time, response code and headers!
Objective-C Shell Swift Other
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A class to stub network requests easily: test your apps with fake network data (stubbed from file) and custom response time

Basic Usage

This is aimed to be very simple to use. It uses block to intercept outgoing requests and allow you to return data from a file instead.

This is the most simple way to use it:

[OHHTTPStubs addRequestHandler:^OHHTTPStubsResponse*(NSURLRequest *request, BOOL onlyCheck)
     return [OHHTTPStubsResponse responseWithFile:@"response.json" contentType:@"text/json" responseTime:2.0];

This will return the NSData corresponding to the content of the "response.json" file (that must be in your bundle) with a "Content-Type" header of "text/json" in the HTTP response, after 2 seconds.

The OHHTTPStubsResponse object

Each time a network request is done by your application (whatever the framework used, NSURLConnection, AFNetworking, or anything else) this requestHandler block will be called, allowing you to return an OHHTTPStubsResponse object describing the response to return. If you return a non-nil OHHTTPStubsResponse, it will automatically build a NSURLResponse and behave exactly like if you received the response from the network. If your return nil, the normal request will be sent

The OHHTTPStubsResponse class exposes multiple initializers:

The designed intializer
Commodity initializer to load data from a file in your bundle
Useful short-form initializer to load data from a file in your bundle, using the specified "Content-Type" header
To respond with an error instead of a success (e.g. [NSError errorWithDomain:NSURLErrorDomain code:404 userInfo:nil])

Advanced Usage

Return a response depending on the request

Of course, and that's the main reason this is implemented with blocks, you can do whatever you need in the block implementation. This includes checking the request URL to see if you want to return a stub or not, and pick the right file according to the requested URL.

Using download speed instead of responseTime

When building the OHHTTPStubsResponse object, you can specify a response time (in seconds) so that the sending of the fake response will be postponed (using GCD's dispatch_after function). This allows you to simulate a slow network for example.

If you specify a negative value for the responseTime parameter, instead of being interpreted as a time in seconds, it will be interpreted as a download speed in KBytes/s. In that case, the response time will be computed using the size of the response's data to simulate the indicated download speed.

The OHHTTPStubsResponse header defines some constants for standard download speeds:

  • OHHTTPStubsDownloadSpeedGPRS : 56 kbps (7 KB/s)
  • OHHTTPStubsDownloadSpeedEDGE : 128 kbps (16 KB/s)
  • OHHTTPStubsDownloadSpeed3G : 3200 kbps (400 KB/s)
  • OHHTTPStubsDownloadSpeed3GPlus : 7200 kbps (900 KB/s)
  • OHHTTPStubsDownloadSpeedWifi : 12000 kbps (1500 KB/s)

Return quickly when onlyCheck=YES

If the onlyCheck parameter of the requestHandler block is YES, then it means that the handler is called only to check if you will be able to return a stubbed response or if it has to do the standard request. In this scenario, the response will not actually be used but will only be compared to nil to check if it has to be stubbed later. The handler will be called later again (with onlyCheck=NO) to fetch the actual OHHTTPStubsResponse object.

So in such cases (onlyCheck==YES), you can simply return nil if you don't want to provide a stubbed response, and any non-nil value to indicate that you will provide a stubbed response later.

This may be useful if you intend to do some no-so-fast work to build your real OHHTTPStubsResponse (like reading some large file for example): in that case you can quickly return a dummy value when onlyCheck==YES without the burden of building the actual OHHTTPStubsResponse object. You will obviously return the real OHHTTPStubsResponse in the later call when onlyCheck==NO.

There is a macro OHHTTPStubsResponseUseStub provided in the header that you can use as a dummy return value for that purpose (it actually evaluates to (OHHTTPStubsReponse*)1)

Stack multiple responseHandlers

You can call +addResponseHandler multiple times. It will just add the response handlers in an internal list of handler.

When a network request is performed by the system, the response handlers are called in the same order that they have been added, and the first non-nil OHHTTPStubsResponse returned is used to reply to the request.

This may be useful to install different stubs in different classes (say different UIViewControllers) and various places in your application.

Complete example

NSArray* stubs = [NSArray arrayWithObjects:@"file1", @"file2", nil];

[OHHTTPStubs addRequestHandler:^OHHTTPStubsResponse*(NSURLRequest *request, BOOL onlyCheck)
     NSString* basename = [request.URL.absoluteString lastPathComponent];
     if (onlyCheck) {
         return ([stubs containsObject:basename] ? OHHTTPStubsResponseUseStub : nil);

     NSString* file = [basename stringByAppendingPathExtension:@"json"];
     return [OHHTTPStubsResponse responseWithFile:file contentType:@"text/json"


// Then this call (sending a request using the AFNetworking framework) will actually
// receive a fake response issued from the file "file1.json"
NSURLRequest* request = [NSURLRequest requestWithURL:[NSURL URLWithString:@""]];
AFJSONRequestOperation* req =
[AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON)
 } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON)
[req start];

ARC Support

This classes are not using ARC.

If you want to use it in an ARC-enabled project, you must add the -fobjc-arc compiler flag to OHHTTPStubs.m and OHHTTPStubsResponse.m in Target Settings > Build Phases > Compile Sources.


This project is brought to you by Olivier Halligon.

It has been inspired by this article from (See also his GitHub repository)

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