Because of the size and weight of the iPad, it becomes quite apparent that the device should naturally be held with two hands, much like a book.
Holding the device this way does create several design challenges, which will alter the way in which we drive users through our application. Let's take a look at a standard iPad interface and how to best place objects on screen so that the app is manageable while holding the device with two hands.
Having an iPad and iPhone on hand, along with a book or notepad for a size comparison will be helpful for this recipe.
The standard hand position for the iPad is different than that for the typical iPhone user, and our application must be build with this fact taken into serious consideration. The way that a device feels in the hand may have been ignored on previous computing platforms, but with the touch-based iOS, it's important that the user can hold the device comfortably while using our app correctly.
The heavier device and requirement of two hands in order to interact with the iPad will require an increase in dexterity, somewhat greater concentration, and an adjusted interface. Here are some tips to make sure that our device works well when using two hands instead of one:
- Increase text size for the larger screen and increased view distance
- Slightly increase button size for all elements
- Place tap buttons near the corner of the screen
- Use swipe and flick often; refrain from taps
The larger size and weight of the iPad will make user interaction a bit more difficult than with the traditional iPhone or iPod touch sized screen. However, when we understand the physical and physiological differences that exist between the two device types, we can adjust our interface accordingly and create a great application.
The iPad is a larger, heavier device than its more mobile predecessors, which creates a difference in design in how we fundamentally structure our application.
While all iOS devices run the same operating system, with identical touch manipulation, the way we interact with content on screen varies quite a bit due to screen size. When we get a chance to hold both devices, it becomes easily apparent as to how each is unique.
The iPhone is typically held with only one hand, using the thumb of the same hand to quickly interact with items on screen. When typing heavily, the thumbs of both fingers may be used while holding the device in either portrait or a landscape orientation. However the iPad is much larger and heavier than the iPhone or iPod touch, making it difficult to hold the device with one hand for an extended period of time. Instead, we'll find that users traditionally hold the iPad with two hands and typical iPhone interactions are no longer possible.
We need to understand these physical limitations of the iPad, as well as the potential inconveniences that arise when using our application. We don't want to create something that requires the user to hold their iPad with one hand and tap on screen for an extended period of time, as it will become quite strenuous and users will refrain from using our app.
With regards to the first point and font size, the increase in distance from eye to screen will require a larger, more legible text for easy reading. In general, we should use a font that is at least twice as large than we would ever consider reasonable on an iPhone screen. Characters that measure one-fourth to nearly one-half an inch in physical size or larger are ideal. Font size can vary greatly based on type-face, style, and other attributes, but this should give us a good guideline to get started with.
If our application cannot be easily read while sitting two feet or slightly further away from the user's face, it will be difficult for our application to be read for extended periods of time.
Likewise, we should also slightly increase the size of our buttons on screen in order to account for the greater distance between face and device. While the minimum optimum button size for an iPhone application is a 44 pixel square, we should make our iPad buttons a minimum of 60 pixels in length or width if possible.
This increase in size also helps the users, as less hand-eye coordination is needed in order to accurately tap the proper location on screen. While user fingers will remain an average size of 44 pixels, the extra bit of leeway will give a bit more room for error.
We should consider the placement of such buttons as well when composing our interface design. On traditional mouse and keyboard computer interfaces, designers are often taught to observe Fitts' law, which in part explains that integral interface items should be placed close to the corners of the screen because these regions are easier for the user to quickly navigate to because the pointer will catch on the end of the screen. It's a useful observance and commonplace in good design.
Much in the same way, we should also place our iPad interface items near the corner of the screen. While we won't be using a mouse and don't need the corners to catch our pointer, such a design is cognitively simple to the user and quick to pick up. It will also allow for the user to tap on screen and not have the large display covered with their hands, giving full visibility of whatever is being altered by an action. Finally, the user's fingers will often be near the side of the screen anyway while sitting on the bezel to hold the device, so it will make for a much more rapid movement when they finally do decide to touch elements on screen.
With regards to the last point, when we do decide to require user action on screen, it's much more preferable to use swipes or flicks than it is to use taps. When possible, we should try our best to replace taps with another gesture.
Because of hand placement on the iPad, it's easier to slide over the thumb and quickly flick on screen than it is to raise a hand off of the device and tap. For nearly all users, no readjustment of the holding hand is necessary to reach with the thumb and make a swipe in any direction.
iBooks is a wonderful example of this, as the thumb can quickly swipe to change pages while the holding hand remains in place. iBooks also lets a user navigate from page to page by tapping the entire right side and left side of the book view. By giving a large tap zone, the user doesn't need to place their hands in any position other than what feels natural, and then make contact through a swipe or touch of the side of the screen in order to turn to the next page.
We'll gain a better understanding as to what gestures and device holding positions are more desirable as we use our gain experience using an iPad. As Apple continues to refine and adjust the device's design, it's guaranteed that the iPad will only become lighter and easier to use. But for the time being, such factors must be taken into account when attempting to build success.
We've discussed how the iPad will be held during use of our application, but with the growing market for iPad cases, does it make sense to design our application around the likelihood of the user having an iPad case?
In the year that the device has been on the market, an unbelievable number of iPad cases have been designed that attempt to help people protect their tablets.
But each case is slightly a different size, is made out of a different material, and ultimately will change the way in which the user holds the iPad.
We're better off not worrying about different case designs and their influence on our app, as we'll always find a case design that will drastically require us to change a part of our app. However if we do put energy into testing our iPad app with a case, we should only worry about Apple designed official cases. The portfolio case of the first iPad and Smart Cover for the iPad 2 account for an estimated 60 to 70 percent of case sales and are going to be the most common case for our user base.