There is a new pre-built control in iOS 5 for incrementing or
decrementing a value, UIStepper. The control has two buttons aligned
horizontally, one labeled with a plus (+) the other a minus (-).
One nice feature is a continuous option, wherein if the user presses and holds down either +/- button, the stepper value is incremented repeatedly. The longer the button is held down, the faster the increment will occur. Also, you can have the increment value wrap around when a range of values is specified, for example, if you set min and max to 0 and 99 respectively, when the value reaches 99, the next value will be 0 (and vice-versa).
Below is a screenshot that shows the output of the example code below:

One nice feature is a continuous option, wherein if the user presses and holds down either +/- button, the stepper value is incremented repeatedly. The longer the button is held down, the faster the increment will occur. Also, you can have the increment value wrap around when a range of values is specified, for example, if you set min and max to 0 and 99 respectively, when the value reaches 99, the next value will be 0 (and vice-versa).
Below is a screenshot that shows the output of the example code below: