This task allows repetitively execute some tasks while task's condition is true. To add a task to "While" task - tap to the task's end "} +" row or move a task there using drag&drop.

The following are properties of "While" task:

Condition: defines loop condition. To make a loop that repeats indefinitely - specify YES or TRUE as a condition. Note, you must have some tasks inside an infinite loop to conditionally break it; otherwise such the loop will be (safely) stopped by runtime at some point. Check the Predicate Format Syntax article for the description of condition format.

Label: optional label, which can be used by a "Break" task to break that particular loop.  

For example, the following workflow repeats 5 times:

i = evaluate(0);
while (i < 5);
 <some tasks to repeat>
 i = evaluate($(i) + 1)

See also:
Common Task Attributes
Task Options
Variable Types