How to use CCProgressTimer in Cocos2D to show progress?

The progress timer takes a
sprite and, based on a percentage, displays only a part of it to visualize some kind of
progress in your game.

CCProgressTimer* timer = [CCProgressTimer progressWithFile:@"progress.png"];
timer.type = kCCProgressTimerTypeRadialCCW;
timer.percentage = 0;
[self addChild:timer z:1 tag: my_tag];
// The update is needed for the progress timer.
[self scheduleUpdate];

You can choose between radial, vertical, and horizontal progress timers. But the timer doesn’t update itself. You have to change the timer’s percentage value frequently to update the progress.