Currently, iOS developers can include PayPal payment buttons into their apps, but users are redirected to Safari to complete their transactions. Now, users will be able to pay without ever leaving the app, including using PayPal's card.io technology that allows users to pay with a credit card by taking a picture of it rather than manually entering the credit card number.
Apple does something similar in iTunes 11 with iTunes Gift Cards.
Mobile SDK – Everyone knows that mobile is changing the way consumers shop and pay, and no one more than developers who must have a mobile presence to compete in today’s environment. We’re launching a mobile SDK so that developers can deliver great experiences for their customers by reducing friction when it comes to payments. Customers never leave the developer’s app experience to pay and they have more choice in the way they want to pay – simply click a PayPal button or scan a credit card using our card.io technology. We’re making it available for iOS developers first, but we’ll expand to other platforms soon.PayPal promises more APIs and capabilities through the rest of 2013.