scroll top and bottom with page control - ios6

Question

Using scrollview with page control for displaying different pages. want to scroll up and down on each page. How can i do that.
[scrollView setContentSize:CGSizeMake(self.view.frame.size.width * 3, self.view.frame.size.height)];
[scrollView setDelegate:self];
[scrollView setPagingEnabled:YES];
scrollView.showsVerticalScrollIndicator = NO;
scrollView.showsHorizontalScrollIndicator = NO;
// Add our views to the scroll view
[scrollView addSubview:pageOne.view];
[scrollView addSubview:pageTwo.view];
[scrollView addSubview:pageThree.view];
[self.view addSubview:self.scrollView];
_pageControl = [[UIPageControl alloc] init];
[_pageControl setCurrentPage:0];
[_pageControl setNumberOfPages:3];
[_pageControl sizeToFit];
[_pageControl setFrame:CGRectMake((scrollView.frame.size.width / 2) - (_pageControl.frame.size.width / 2), scrollView.frame.size.height - _pageControl.frame.size.height, _pageControl.frame.size.width, _pageControl.frame.size.height)];
[self.view addSubview:self.pageControl];
How can i enable scrolling up and down on each page.
Thanks for help.

Answer 1

You need to monitor the UIControlEventValueChanged event to determine when the page control has changed pages. You can do this programmatically view the addTarget method.
[_pageControl addTarget:self action:#selector(positionChanged)
forControlEvents:UIControlEventValueChanged];
This tells the page control to call the positionChanged method in the current object, whenever the page is changed. The positionChanged method can then look at the currentPage of the page control to determine where to move to.
So the positionChanged method might look something like this:
- (void)positionChanged {
NSUInteger page = [_pageControl currentPage];
CGFloat yoffset = self.view.frame.size.height * page;
[scrollView setContentOffset:CGPointMake(0,y)];
}
Don't forget that you'll need to call removeTarget sometime before your object is destroyed, possibly in your dealloc method.
[_pageControl removeTarget:self action:#selector(positionChanged)
forControlEvents:UIControlEventValueChanged];
Code hasn't been tested, but hopefully that's enough to get you started.
If you don't want to do this programmatically, you can also connect your page control to the positionChanged method using the Xcode Interface Builder. The details are explained in the Xcode User Guide.