Apple Watch was the leading smartwatch in the second quarter, with an estimated 4 million shipped worldwide, for a market share of more than 75 percent, according to Strategy Analytics. [...] the market is still nascent, and Apple Watch isn't an option for people who use Android smartphones. [...] watches running Google's Android Wear software will now work with Apple's iPhones. The S2 has a circular frame that can be rotated to scroll through notifications and apps, so your fingers won't tire out from endless swiping. [...] many leading app developers have focused on Apple Watch and Android Wear instead, as Samsung watches use a little-known system called Tizen. In a surprise move, Samsung is making the S2 work with a range of Android smartphones, though some features, such as setting alarms, might not work with all phones. Consumers get choice, without compromising on app selection, as developers can write apps just once for multiple devices. Sport will have GPS built-in, along with a screen that can adapt to bright sunlight, with high-contrast text and graphics for better visibility in glare.