The Pros and Cons of Building a Contact Tracing Application for the Pandemic on iOS

Contact tracing has come about as a digital solution to the current health crisis that has rattled the world, COVID-19. The roots of contact tracing can be found during the SARS crisis when manual contact tracing became a method of identifying possible carriers of the virus.

In the wake of COVID-19, countries like South Korea, Singapore, and Israel have developed their own digital contact tracing platforms and have shown promising results.

On 10th April 2020, both Apple and Google announced that they would be releasing an API that allows interoperability between devices using apps from public health authorities. The future also finds these tech giants building contact tracing functionality within the platforms themselves for a more robust solution.

What is contact tracing, what are its important features, and limitations? Let’s find out.

What Is a Contact Tracing App?

A contact tracing app is a proximity detector that uses low-energy Bluetooth to identify devices that come into close contact with another device.

The app uses a unique code or identifier that changes frequently and transmits it to other devices. It logs the codes received and sent by the device. The app also monitors these logs for updates, in case anyone has flagged themselves after testing positive for COVID-19.BLE

If a device identifier is reported to have flagged themselves, the app checks it in the log and sends out an instant alert to the user of that app about possible exposure.

Important Features and Functionalities

Apart from the general infrastructure of the app, these are some of the features that developers will have to code in order to create a contact tracing app on iOS.

Contact Detection Service

Contact detection is a registered Low-energy Bluetooth service with Bluetooth SIG (16-bit service UUID). Contact Detection Services enable devices to perform proximity sensing of the unique identifiers called “Rolling Proximity Identifiers” between different devices to monitor the possible event of exposure.

The 16-bit service UUID allows the device to scan and advertise the Rolling Proximity Identifiers and uses a service Data type that contains a 128-bit Rolling Proximity Identifier, that is designed to change periodically.

Daily Tracking Key generation

The app derives a tracing key every 24 hours for privacy protection, to ensure that the key cannot be used to identify remotely, the identity of the key generator. This has to be performed every 24 hours to ensure the active masking of a device’s identity.

Rolling Proximity Identifier

A rolling proximity identifier is derived from this tracing key and advertised using the BLE service to other devices in the proximity. This identifier is set to change every 15 minutes to stop wireless tracking of a device and to ensure complete anonymity and privacy of the app’s users.

Push Notification and Alerts

If an identifier is flagged for contracting COVID-19, the app sends an alert on the mobile device, including time, date, and area of possible contraction, and can provide tips and next steps, depending on the app’s complexity.

Automated Log Monitoring

In order to ensure active and timely reporting, the app is designed to automatically monitor the log it stores of the Rolling proximity identifiers in case of an update, signaling that one of the identifiers has tested positive for COVID-19.

Timestamp Recording

The app also could record timestamps for purposes of accuracy. Though it’s not a necessity, it can help narrow down the location of the potential exposure for further tracing by health authorities.

How Much Does It Cost To Build A Contact Tracing App?

Just like any other app, the cost to build a contact tracing app also varies, depending on where you get it developed, the iOS app development company you hire, or if you’re the company yourself, the resources you leverage for the development.

An estimate that you can keep in your mind while stepping into developing a contact tracing app would be $25,000- 50,000 for iOS.

Functional Limitations and Problems

Some critics of Bluetooth technology have although mentioned that such a platform can result in a lot of false positives. Bluetooth technology cannot understand if there’s a wall between two people and is too reliant on proximity.

There might be a concrete wall between two people, and yet proximity alerts would catch that and tell the app’s user that they might be exposed, even though there’s no possible way that would have happened.

A contact tracing app can result into inaccurate alerts raising unnecessary panic among individuals. We do not know how far the COVID-19 particles travel can so it also is possible that they can reach places that are out of Bluetooth range, and don’t work to alert people who might be at risk.

Privacy is another issue that skeptics have talked about. The answer to concern over breach of privacy and misuse of data is simple – as a company, as an industry, the way to solve privacy problems with regards to contact tracing apps is to make it opt-in and regulate our own use of data. This could be done by allowing 3rd party audits and checks and by limiting the storage of data on local devices rather than company-owned servers.


The technology is nowhere near perfect, and it is not the single solution to the COVID-19 pandemic. Though, it can add a resource to the toolkit of our health sector that can help combat the virus alongside other strategies, such as social distancing, mass testing, and quarantines.

Until there’s a vaccine developed, the preventative measures required are massive, and fighting this battle on the digital end using mobile devices that have a tremendous use rate in the world can be an effective way to reduce the spread. Even if it’s not perfect, saving one life is enough of a reason to venture into a solution.