The UK's Competition and Markets Authority started an investigation into Apple's alleged anti-competitive behaviour.
The investigation was started after "several developers [reported] that Apple's terms and conditions are unfair and could break competition law," the CMA said.
The investigation will particularly be looking into the fact that Apple is preventing third-party developers from using their own payment system, which is what triggered the ongoing dispute with Epic Games.
Other aspects under scrutiny will include the infamous commission that Apple takes on transactions on the App Store, which can be up to 30%.
Andrea Coscelli, chief executive of the CMA, commented: "Millions of us use apps every day to check the weather, play a game or order a takeaway. So, complaints that Apple is using its market position to set terms which are unfair or may restrict competition and choice -- potentially causing customers to lose out when buying and using apps -- warrant careful scrutiny.
"Our ongoing examination into digital markets has already uncovered some worrying trends. We know that businesses, as well as consumers, may suffer real harm if anti-competitive practices by big tech go unchecked. That's why we're pressing on with setting up the new Digital Markets Unit and launching new investigations wherever we have grounds to do so."
Earlier this year, Epic expanded its ongoing legal battle against Apple and Google by filing a complaint in the UK against each of the mobile platform holders.