Objective-C (iOS) (0.4.0)

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1. Overview

The Snowplow iOS Tracker allows you to track Snowplow events from your iOS apps and games. It supports iOS 7.0+.

The tracker should be straightforward to use if you are comfortable with iOS development; its API is modelled after Snowplow's Python Tracker so any prior experience with that tracker is helpful but not necessary. If you haven't already, have a look at the iOS Tracker Setup guide before continuing.

You can also find detailed documentation for the method calls in the tracker classes available as part of the CocoaPods documentation.

2. Initialization

Assuming you have completed the iOS Tracker Setup for your project, you are now ready to initialize the Snowplow Tracker.

2.1 Importing the library

Adding the library into your project is as simple as adding the headers into your class file:

#import <SnowplowTracker.h>
#import <SnowplowEmitter.h>

If you have manually copied the library into your project, don't forget to change your import syntax:

#import "SnowplowTracker.h"
#import "SnowplowEmitter.h"

That's it - you are now ready to initialize a tracker instance.

2.2 Creating a tracker

To instantiate a tracker in your code simply instantiate the SnowplowTracker class with the constructor:

- (id) initWithCollector:(SnowplowEmitter *)collector_
                   appId:(NSString *)appId_
           base64Encoded:(Boolean)encoded
               namespace:(NSString *)namespace_

For example:

SnowplowTracker *t1 = [[SnowplowTracker alloc] initWithCollector:collector appId:@"AF003" base64Encoded:false namespace:@"cloudfront"];

Argument Name	Description
`collector`	The SnowplowEmitter object you create
`namespace`	The name of the tracker instance
`appId`	The application ID
`base64Encoded`	Whether to enable base 64 encoding

2.2.1 `collector`

This is a single SnowplowEmitter object that will be used to send all the tracking events created by the SnowplowTracker to a collector. See Sending events for more on its configuration.

2.2.2 `namespace`

If provided, the namespace argument will be attached to every event fired by the new tracker. This allows you to later identify which tracker fired which event if you have multiple trackers running.

2.2.3 `appId`

The appId argument lets you set the application ID to any string.

2.2.4 `base64Encoded`

By default, unstructured events and custom contexts are encoded into Base64 to ensure that no data is lost or corrupted. You can turn encoding on or off using the Boolean base64Encoded argument.

3. Adding extra data

Unlike the other Trackers, the iOS tracker automatically collects your platform, screen resolution, viewport, color depth, timezone and language from the device. You can still however, set your user ID to properly track different users if you require it.

setUserId
Sending IFA

3.1 Set user ID with `setUserId`

You can set the user ID to any string:

s1.setUserId( "{{USER ID}}" )

Example:

[tracker setUserId:@"alexd"];

3.2 Sending IFA

Apps that do not display advertisements are not allowed to access Apple's Identifier For Advertisers (IFA). For this reason, the Snowplow iOS Tracker will only send IFA as part of the mobile_context which is attached to each event if you have the AdSupport.framework included in your app (and are therefore intending to serve ads).

For the avoidance of doubt, you can also avoid sending IFA regardless of your advertising situation, thus:

Click on Build Settings to your app's project in Xcode
Search for Preprocessor Macros
Add a macro defined asSNOWPLOW_NO_IFA = 1

4. Tracking specific events

Snowplow has been built to enable you to track a wide range of events that occur when users interact with your websites and apps. We are constantly growing the range of functions available in order to capture that data more richly.

Tracking methods supported by the iOS Tracker at a glance:

Function	*Description
`trackScreenView:`	Track the user viewing a screen within the application
`trackPageView:`	Track and record views of web pages.
`trackEcommerceTransaction:`	Track an ecommerce transaction and its items
`trackStructuredEvent:`	Track a Snowplow custom structured event
`trackUnstructuredEvent:`	Track a Snowplow custom unstructured event
`trackTiming:`	Track a Snowplow user timing event

4.1 Common

All events are tracked with specific methods on the tracker instance, of the form trackXXX(), where XXX is the name of the event to track.

4.1.1 Custom contexts

In short, custom contexts let you add additional information about the circumstances surrounding an event in the form of an NSDictionary object. Each tracking method accepts an additional optional contexts parameter after all the parameters specific to that method:

- (void) trackPageView:(NSString *)pageUrl
                 title:(NSString *)pageTitle
              referrer:(NSString *)referrer;
- (void) trackPageView:(NSString *)pageUrl
                 title:(NSString *)pageTitle
              referrer:(NSString *)referrer
               context:(NSMutableArray *)context;
- (void) trackPageView:(NSString *)pageUrl
                 title:(NSString *)pageTitle
              referrer:(NSString *)referrer
             timestamp:(double)timestamp;
- (void) trackPageView:(NSString *)pageUrl
                 title:(NSString *)pageTitle
              referrer:(NSString *)referrer
               context:(NSMutableArray *)context
             timestamp:(double)timestamp;

The context argument should consist of a NSArray of NSDictionary representing an array of one or more contexts. The format of each individual context element is the same as for an unstructured event.

If a visitor arrives on a page advertising a movie, the context dictionary might look like this:

{
  "schema": "iglu:com.acme_company/movie_poster/jsonschema/2.1.1",
  "data": {
    "movieName": "The Guns of Navarone",
    "posterCountry": "US",
    "posterYear": "1961"
  }
}

The corresponding NSDictionary would look like this:

NSDictionary *poster = @{
                         @"schema":@"iglu:com.acme_company/movie_poster/jsonschema/1-0-0",
                         @"data": @{
                                 @"movieName": @"The Guns of Navarone",
                                 @"posterCountry": @"US",
                                 @"posterYear": @"1961"
                                 }
                         };

Sending the movie poster context with an event looks like this:

[tracker trackStructuredEvent:@"Product"
                       action:@"View"
                        label:nil
                     property:nil
                        value:0
                      context:[NSMutableArray arrayWithArray:@[poster]]];

Note that even if there is only one custom context attached to the event, it still needs to be placed in an array.

4.1.2 Optional timestamp & context argument

In all the trackers, we offer a way to set the timestamp if you want the event to show as tracked at a specific time. If you don't, we create a timestamp while the event is being tracked.

Here is an example:

[tracker trackPageView:@"www.page.com" title:@"Example Page" referrer:@"www.referrer.com"];
[tracker trackPageView:@"www.page.com" title:@"Example Page" referrer:@"www.referrer.com" context:contextArray];
[tracker trackPageView:@"www.page.com" title:@"Example Page" referrer:@"www.referrer.com" timestamp:1234567890];
[tracker trackPageView:@"www.page.com" title:@"Example Page" referrer:@"www.referrer.com" context:contextArray timestamp:1234567890];

4.1.3 Tracker method return values

To be confirmed. As of now, trackers do not return anything.

4.2 Track screen views with `trackScreenView:`

Use trackScreenView: to track a user viewing a screen (or equivalent) within your app. Arguments are:

Argument	Description	Required?	Validation
`name`	Human-readable name for this screen	No	NSString*
`id_`	Unique identifier for this screen	No	NSString*
`context`	Custom context for the event	No	NSMutableArray*
`timestamp`	Optional timestamp for the event	No	double

Example:

[t1 trackScreenView:@"HUD > Save Game" screen:@"screen23"];
[t1 trackScreenView:@"HUD > Save Game" screen:nil timestamp:12435678];
[t1 trackScreenView:@"HUD > Save Game" screen:@"screen23" timestamp:12435678];

4.3 Track pageviews with `trackPageView:`

Use trackPageView: to track a user viewing a page within your app.

Arguments are:

Argument	Description	Required?	Validation
`pageUrl`	The URL of the page	Yes	NSString*
`pageTitle`	The title of the page	Yes	NSString*
`referrer`	The address which linked to the page	Yes	NSString*
`context`	Custom context for the event	No	NSMutableArray*
`timestamp`	Optional timestamp for the event	No	double

Example:

[t1 trackPageView:@"www.example.com" title:@"example" referrer:@"www.referrer.com" context:contextList];
[t1 trackPageView:@"www.example.com" title:@"example" referrer:@"www.referrer.com"];

4.4 Track ecommerce transactions with `trackEcommerceTransaction:`

Use trackEcommerceTransaction: to track an ecommerce transaction. Arguments:

Argument	Description	Required?	Validation
`orderId`	ID of the eCommerce transaction	Yes	NSString*
`totalValue`	Total transaction value	Yes	float
`affiliation`	Transaction affiliation	No	NSString*
`taxValue`	Transaction tax value	No	float
`shipping`	Delivery cost charged	No	float
`city`	Delivery address city	No	NSString*
`state`	Delivery address state	No	NSString*
`country`	Delivery address country	No	NSString*
`currency`	Transaction currency	No	NSString*
`items`	Items in the transaction	Yes	NSMutableArray*
`context`	Custom context for the event	No	NSMutableArray*
`tstamp`	When the transaction event occurred	No	double

trackEcommerceTransaction: fires multiple events: one "transaction" event for the transaction as a whole, and one "transaction item" event for each element of the items array. Each transaction item event will have the same timestamp, orderId, and currency as the main transaction event.

The items argument is an NSMutableArray containing an NSDictionary for each item in the transaction. There is a convenience constructor for each item called trackEcommerceTransactionItem:. Arguments:

Field	Description	Required?	Validation
`sku`	Item SKU	Yes	NSString*
`price`	Item price	Yes	float
`quantity`	Item quantity	Yes	float
`name`	Item name	No	NSString*
`category`	Item category	No	NSString*
`context`	Custom context for the event	No	NSMutableArray*
`currency`	Transaction currency	No	NSString*
`context`	Custom context for the event	No	NSMutableArray*
`tstamp`	When the transaction event occurred	No	double

Example of tracking a transaction containing one item:

NSString *transactionID = @"6a8078be";
NSMutableArray *itemArray = [NSMutableArray array];

[itemArray addObject:[t trackEcommerceTransactionItem:transactionID
                                                  sku:@"pbz0026"
                                                 name:@"Hot Chocolate"
                                             category:@"Drink"
                                                price:0.75F
                                             quantity:1
                                             currency:@"USD"]];

[t trackEcommerceTransaction:transactionID totalValue:350 affiliation:@"no_affiliate" taxValue:10 shipping:15 city:@"Boston" state:@"Massachusetts" country:@"USA" currency:@"USD" items:itemArray];

4.5 Track structured events with `trackStructuredEvent:`

Use trackStructuredEvent: to track a custom event happening in your app which fits the Google Analytics-style structure of having up to five fields (with only the first two required):

Argument	Description	Required?	Validation
`category`	The grouping of structured events which this `action` belongs to	Yes	NSString*
`action`	Defines the type of user interaction which this event involves	Yes	NSString*
`label`	A string to provide additional dimensions to the event data	Yes	NSString*
`property`	A string describing the object or the action performed on it	Yes	NSString*
`value`	A value to provide numerical data about the event	Yes	int
`context`	Custom context for the event	No	NSMutableArray*
`timestamp`	Optional timestamp for the event	No	double

Example:

[t1 trackStructuredEvent:@"shop" action:@"add-to-basket" label:@"Add To Basket" property:@"pcs" value:27];
[t1 trackStructuredEvent:@"shop" action:@"add-to-basket" label:@"Add To Basket" property:@"pcs" value:27 timestamp:1234569];

4.6 Track unstructured events with `trackUnstructuredEvent:`

Custom unstructured events are a flexible tool that enable Snowplow users to define their own event types and send them into Snowplow.

When a user sends in a custom unstructured event, they do so as a JSON of name-value properties, that conforms to a JSON schema defined for the event earlier.

Use trackUnstructuredEvent: to track a custom event which consists of a name and an unstructured set of properties. This is useful when:

You want to track event types which are proprietary/specific to your business (i.e. not already part of Snowplow), or
You want to track events which have unpredictable or frequently changing properties

The arguments are as follows:

Argument	Description	Required?	Validation
`eventJson`	The properties of the event	Yes	NSDictionary*
`context`	Custom context for the event	No	NSMutableArray*
`timestamp`	Optional timestamp for the event	No	double

Example:

- (void) trackUnstructuredEvent:(NSDictionary *)eventJson
                        context:(NSMutableArray *)context
                      timestamp:(double)timestamp;

If you supply a NSDictionary*, make sure that this top-level contains your schema and data keys, and then store your data properties as a child NSDictionary*.

Example:

NSDictionary *event = @{
                          @"schema":@"iglu:com.acme/save_game/jsonschema/1-0-0",
                          @"data": @{
                                  @"level": @23,
                                  @"score": @56473
                                  }
                          };
tracker trackUnstructuredEvent:event
                        context:nil
                      timestamp:12345678;

For more on JSON schema, see the blog post.

4.7 Track user timings with `trackTimingWithCategory:`

Use trackTiming: to track a user timing in your app - for example, how long a game took to load, or how long an in-app purchase took to download. The fields are as follows:

Argument	Description	Required?	Validation
`category`	Categorizing timing variables into logical groups (e.g API calls, asset loading)	Yes	NSString*
`variable`	Identify the timing being recorded	Yes	NSString*
`timing`	The number of milliseconds in elapsed time to report	Yes	NSUInteger
`label`	Optional description of this timing	Yes	NSString*
`context`	Custom context for the event	No	NSMutableArray*
`timestamp`	Optional timestamp for the event	No	double

Example:

[t1 trackTimingWithCategory:@"Application"
                   variable:@"Background"
                     timing:324
                      label:@"5231804123"];

[t1 trackTimingWithCategory:@"Application" variable:@"Background" timing:324 label:@"5231804123" timestamp:1234569];

5. Sending events: `SnowplowEmitter`

Events created by the Tracker are sent to a collector using a SnowplowEmitter instance. You can create one using one of the init methods:

- (id) initWithURLRequest:(NSURL *)url
               httpMethod:(NSString *)method
             bufferOption:(enum SnowplowBufferOptions)option;
- (id) initWithURLRequest:(NSURL *)url
               httpMethod:(NSString* )method;

For example:

NSURL *url = [[NSURL alloc] initWithString:@"https://collector.acme.net"];
SnowplowEmitter emitter = [[SnowplowEmitter alloc] initWithURLRequest:url
                                                           httpMethod:@"POST"
                                                         bufferOption:SnowplowBufferInstant];
SnowplowEmitter emitter2 = [[SnowplowEmitter alloc] initWithURLRequest:url
                                                            httpMethod:@"GET"];

5.1 Using a buffer

A buffer is used to group events together in bulk before sending them. This is especially handy to reduce network usage. By default, the SnowplowEmitter buffers up to 10 events before sending them.

You can set this during the creation of a SnowplowEmitter object or using the setter -(void)setBufferOption:

NSURL *url = [[NSURL alloc] initWithString:@"https://collector.acme.net"];
SnowplowEmitter emitter = [[SnowplowEmitter alloc] initWithURLRequest:url
                                                           httpMethod:@"POST"
                                                         bufferOption:SnowplowBufferInstant];
SnowplowEmitter emitter2 = [[SnowplowEmitter alloc] initWithURLRequest:url
                                                           httpMethod:@"POST"
                                                         bufferOption:SnowplowBufferDefault];

[emitter setBufferOption:SnowplowBufferInstant];

Here are all the posibile options that you can use:

Option	Description
`SnowplowBufferInstant`	Events are sent as soon as they are created
`SnowplowBufferDefault`	Sends events in a group when 10 events are created

5.2 Choosing the HTTP method

Snowplow supports receiving events via GET requests, but will soon have POST support. In a GET request, each event is sent in individual request. With POST requests, events are bundled together in one request.

Here are all the posibile options that you can use:

Option	Description
`@"GET"`	Events are sent individually as GET requests
`@"POST"`	Events are sent in a group when 10 events are received in one POST request

5.3 Sending HTTP requests

You can set this during the creation of a SnowplowEmitter object:

NSURL *url = [[NSURL alloc] initWithString:@"https://collector.acme.net"];
SnowplowEmitter emitter = [[SnowplowEmitter alloc] initWithURLRequest:url
                                                           httpMethod:@"POST"
                                                         bufferOption:SnowplowBufferInstant];
SnowplowEmitter emitter2 = [[SnowplowEmitter alloc] initWithURLRequest:url
                                                           httpMethod:@"GET"
                                                         bufferOption:SnowplowBufferDefault];

1. Overview​

2. Initialization​

2.1 Importing the library​

2.2 Creating a tracker​

2.2.1 collector​

2.2.2 namespace​

2.2.3 appId​

2.2.4 base64Encoded​

3. Adding extra data​

3.1 Set user ID with setUserId​

3.2 Sending IFA​

4. Tracking specific events​

4.1 Common​

4.1.1 Custom contexts​

4.1.2 Optional timestamp & context argument​

4.1.3 Tracker method return values​

4.2 Track screen views with trackScreenView:​

4.3 Track pageviews with trackPageView:​

4.4 Track ecommerce transactions with trackEcommerceTransaction:​

4.5 Track structured events with trackStructuredEvent:​

4.6 Track unstructured events with trackUnstructuredEvent:​

4.7 Track user timings with trackTimingWithCategory:​

5. Sending events: SnowplowEmitter​

5.1 Using a buffer​

5.2 Choosing the HTTP method​

5.3 Sending HTTP requests​

1. Overview

2. Initialization

2.1 Importing the library

2.2 Creating a tracker

2.2.1 `collector`

2.2.2 `namespace`

2.2.3 `appId`

2.2.4 `base64Encoded`

3. Adding extra data

3.1 Set user ID with `setUserId`

3.2 Sending IFA

4. Tracking specific events

4.1 Common

4.1.1 Custom contexts

4.1.2 Optional timestamp & context argument

4.1.3 Tracker method return values

4.2 Track screen views with `trackScreenView:`

4.3 Track pageviews with `trackPageView:`

4.4 Track ecommerce transactions with `trackEcommerceTransaction:`

4.5 Track structured events with `trackStructuredEvent:`

4.6 Track unstructured events with `trackUnstructuredEvent:`

4.7 Track user timings with `trackTimingWithCategory:`

5. Sending events: `SnowplowEmitter`

5.1 Using a buffer

5.2 Choosing the HTTP method

5.3 Sending HTTP requests