Considerations for SKAN 3.0 Postbacks

Jusang SongWritten by Jusang Song,

Several considerations for SKAdNetwork (SKAN) 3.0 postbacks need to be taken into account for the successful implementation of the privacy-preserving framework. SKAN sends postbacks containing the attribution data to ad channels which are forwarded to Airbridge. Therefore to receive SKAN data in Airbridge, ad channels that serve your ads must support SKAN to receive SKAN data in Airbridge.

Setting Conversion Values

To protect user privacy, SKAN sends postbacks containing conversion values, limiting the amount of event data shared. SKAN uses the conversion value mapping you create to send postbacks. For example, if an “Order Complete” event occurs, instead of sending the event data, SKAN sends the conversion value that is mapped to that event.

Therefore setting the conversion values in a way that is well-aligned with your business goals and marketing context is essential to effectively measure your iOS campaigns via SKAN. Read the following guide to learn how to set the conversion values in Airbridge.

Privacy Threshold

The privacy threshold is another restraint imposed by Apple to preserve user privacy. If the number of daily installs does not reach a certain threshold, SKAN sends postbacks with null conversion values.

Apple hasn’t defined the actual caps of the daily install numbers. See the following table for recommendations offered by major ad channels on the minimum number of daily installs to receive event data from SKAN.


Ad channel


Facebook (Meta)


Unity Ads



Minimum daily installs to receive post-install data




For example, Facebook recommends that at least 88 installs must occur on a daily basis per campaign whereas Google advises running a maximum of 8 iOS app campaigns to receive SKAN 3.0 postbacks.


The minimum daily installs are recommendations suggested by ad channels, and therefore SKAN may still send postbacks with null conversion values even if the numbers are met.

Data Discrepancy

SKAN sends postbacks with null conversion values when the privacy threshold is not met. This means that when you receive a postback with a null conversion value, install events are collected but the post-install events are not.

This could lead to a data discrepancy between your first-party data and the SKAN data displayed in the Airbridge reports. If the SKAN postbacks contain null conversion values, the SKAN installs and the installs from internal data should match, but the number of post-install events from SKAN data will be lower than that from the internal data.

Avoid null conversion values

Follow the recommendations below to prevent SKAN from sending null conversion values.


The recommendations below don’t guarantee that the privacy threshold is met and you may continue receiving null conversion values as SKAN postbacks are dependent on Apple’s privacy policies.

  • Once you start your iOS campaign, wait for at least 72 hours to view data.

  • Run a few campaigns on selective channels. Don’t run multiple channels across lots of channels at once.

  • Expand the target audience of your campaign. If the campaign is targeted to a small audience, the installs may remain small in number.

Measurement Window and Random Postback Timer

SKAN measures the in-app events for 24 hours upon app install. If a specified event is triggered before this measurement window ends, the corresponding conversion value is recorded and the 24 hour-window is opened again. If another event is triggered, the conversion value is updated to the new value. However, the Airbridge SDK limits the measurement window for event data collection to the initial 24 hours upon app install.

Once the measurement window is closed, the random postback timer is initiated which is set to 0-24 hours and the postback is sent at a random time during that 24-hour window. Consequently, the SKAN data is made available in Airbridge 24-48 hours after app installation. Facebook and Google Ads SKAN data may be delayed as Facebook and Google Ads aggregate the postbacks and pass them daily to Airbridge at a fixed time.

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