Rather than being touch-enabled, applications can be touch-optimised, that is, designed primarily for touch screen interaction. When developing applications for a touch interface, consider which interactions benefit the most from a touch UI. While physical strokes and gestures provide a natural interaction with objects, the fact that one can apply them does not mean they are appropriate for every situation.

Here are two tips for designing applications for touch use. First, base your design decisions on real, considered touch use cases. Second, as touch functions require a fair amount of discovery from the user, make only the most obvious functions touch-enabled.

Why to use touch

• More flexible: Compared to fixed hardware keys, the interface can change dynamically. This allows for flexible configurations depending on the functionality needs, languages, and so on. Thus, even a very small screen can include several button sets. Also, with indirect strokes and gestures, there are numerous possibilities. No use of physical buttons is required.

• More intuitive: Manipulating objects directly by touching them is natural and intuitive. Keyboards, mice, trackballs, and other input devices are not able to convey as much subtlety as touch can. Direct manipulation can deliver a lot more meaning to controlling a tool.

• More fun: You can design a game in which the user presses a button, and an on-screen avatar swings a tennis racket. It can be simply more entertaining to mimic movements physically and to see the action mirrored on-screen. Strokes and gestures encourage play and exploration of a system by providing a hands-on experience.

• More engaging: Through play, users start to engage with the interface, first by trying it out to see how it works.

Limitations of touch

• Heavy data input: A hardware keyboard is faster for most people to use when entering a large amount of text or numbers, and applications which involve heavy data input are not necessarily ideal for touch devices. Virtual keyboards are adequate, for example, for messaging applications. Consider using adaptive methods – such as options and selections filtered according to what is available on the screen or in a list – and pre-filled items, when possible.

• Reliance on the visual: While touch devices provide tactile feedback capability, some applications can rely heavily on visual feedback to indicate actions. Provide scalability, larger buttons and text sizes, for example, for visually impaired users.

• Reliance on the physical: Touch interface can be more demanding on the physical context than mechanical keys. Tapping a touch screen button while wearing winter gloves, or with long fingernails can be difficult, for instance. The inverse is also true: the more subtle and small the movement, the less likely it is that everyone will be able to do it. To overcome this, the most basic use cases, such as answering an incoming phone call, must utilise large enough elements and straightforward interaction.