While no operating system is foolproof, iOS
has been relatively exploit-free given the attention that's on it. And with the impending launch of iOS 8 this fall, Apple's ratcheting things up in a bid to add even more user privacy -- something that is becoming more of a foreign concept as advertisements grow and users become the product. With iOS 8, Apple will eliminate the unique device number that marketing clients and app devs have used to track users and their usage.
Essentially, iOS 8 will generate a random MAC address while scanning for a Wi-Fi network, which means that companies collecting that data won't be able to align things as they have before to track your hops around the Internet. In iOS 7, Apple bars app developers from using MAC addresses to track the quantity of people that have installed their apps, but iOS 8 takes it a step further. As Apple puts it: "The MAC address used for Wi-Fi scans may not always be the device’s real (universal) address."
It sounds minor in the grand scheme of things, but it's a pretty meaningful step for privacy, and we're hoping that other mobile OS providers follow suit.