5.2. Keyboard Keys

In this section, we introduce you to the keys of the phone keyboard. Although there is nothing particularly difficult in registering the click of a key, there are several things worth noticing.

First, a single physical key may produce different results based on the keyboard mode: for instance, a key might produce an upper or lower case 'a' depending whether some other key is active. Second, there are several different key events: the user can select a key, hold it down and release it – all these events can be registered separately.

With the help of the next three examples, we show three different approaches to programming keyboard keys. Each example takes a slightly different approach, but basically they all do the same thing:

  • If the user presses the up-arrow key (navigation key up), a note dialog tells us that the up-arrow key was pressed, as shown in Figure 5.2.

  • If the user presses keyboard key 2, a note dialog tells us that key 2 was pressed.

Figure 5-2. Up arrow is pressed

Even though all three approaches are used here to accomplish the same task, each of them is best suited to handle a particular use case:

  • The first approach (Section 5.2.1) is handy when you need to handle the clicks of only a few specific keys.

  • The second approach (Sections 5.2.2) is suitable if you need more complicated processing of several keys.

  • The third approach (Section 5.2.3) is a ...

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