Apple's logo for its programming language, Swift. Source: Apple

Apple's (NASDAQ:AAPL) Worldwide Developer Conference had an eventful first day this week. Investors and fans were treated to the introduction of a new desktop operating system, OS X El Capitan, the newest upgrade of its mobile operating system, iOS 9, and the continued push for Apple into the music industry with its Beats streaming radio offering and Apple Music upgrades. All-in-all, a solid first day for Apple fans.

For attendees, a mostly developer-oriented audience, perhaps the most important announcement was lost among the casual watchers tuning in from their Macs, iPads, and iPhones. Nearly a year after Apple introduced its new programming language, Swift, the company announced Swift 2.0, along with the huge announcement that Swift will be going open source.

Open source pros ...
Open source is akin to a double-edge sword. On one hand, there are many reasons to go that route and give developers more latitude. For a comparison, look no further than Apple's mobile OS competitor, Google (NASDAQ:GOOG) (NASDAQ:GOOGL) Android, for the pros of open source. One of the obvious benefits of open source is it fuels innovation as many developers are able to bring skills and competencies outside of the ones direct employees have.

In nascent and developing markets, open sourcing increases the chances your product will become the accepted marketplace standard, allowing your company to acquire significant market share in the process. Open-source Android boasted 81.5% of all smartphone shipments and a massive 1 billion smartphones with Android were shipped last year as Asia markets came online in a major way.

... and cons
On the other hand, there are negatives with open source. First, and a big issue specific to Android, is the fragmentation problem. For example, Apple's newest mobile operating system, iOS 8, has an adoption rate of 83% as Apple can push it out to all users at once, while Google's recent version, Lollipop, has a 12% adoption rate as the OS is on many different devices not controlled by Google. This presents issues for developers, especially from a security standpoint, and can degrade the user experience as optimization suffers.

Next, there's the potential of losing your ability to monetize if you go open source. While Google's Android is on solid ground domestically, as its APIs are required to connect the open-source software/OS to third-party plugins desperately needed here in the U.S., a cautionary tale is occurring in China as hardware partners and a nationalistic government have paired up to deny Google full monetization of its Android OS there.

Apple will not become Google here
In Apple's case, this isn't a full-blown operating system open-source conversion where Apple gives away its walled garden to any hardware manufacturer that wants to use it. This is simply opening up the programming language that developers use to make apps and software for Apple's operating systems. Apple will still firmly control its ecosystem, and users shouldn't expect any changes from a user-experience standpoint from Swift going open source.

However, by opening up the programming code, developers who work on Swift everyday can provide input and updates to make the programming language more efficient and to provide an even better user experience through collaboration and innovation. At the very least, Apple's move should make it easier for developers to build and update apps, improving the experience for all Apple users.