Easiest way to do this is add some transparent UIButton instances on UIScrollView, set actions and do something in each button.
for example,
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch
...
UIButton* someButton = [[[UIButton alloc] initWithFrame:CGRectMake(100.0f, 100.0f, 100.0f, 100.0f)] autorelease];
[someButton addTarget:self action:@selector(doSomething) forControlEvents:UIControlEventTouchDown];
[someUIScrollView addSubview:someButton];
...
}
- (void)doSomething {
NSLog(@"Do something");
}
You should write some codes for judging whether touched point is inside or not, if you want to create non-rect spot (such as circle). But considering finger size and user recognition, I think you don't have to implement a strict judgement.