Learning the basics of UIScrollView

37
votes

I've been having a very hard time finding good examples of UIScrollView. Even Apple's UIScrollView Suite I find a bit lacking.

I'm looking for a tutorial or example set that shows me how to create something similar to the iPhone Safari tab scrolling, when you zoom out from one browser window and can flick to others.

But I'm having a hard time just getting any old view showing within a scroll view. I have a view set up with an image in it, but when I add it to the scroll view, I only get a black rectangle, no matter what I put in the view I add.

Any links or code snippets would be great!

3
iphoneobjective-ciphone-sdk-3.0uiscrollview
Can you explain what you mean by iPhone Safari tab scrolling? Is that after you click on the bottom-right page button and then you get a UIPageControl that let's you flick to other browser windows? - mahboudz

3 Answers

46
votes

Here is a scroll view guide from Apple

The basic steps are:

  1. Create a UIScrollView and a content view you want to put inside (in your case a UIImageView).
  2. Make the content view a subview of the scroll view.
  3. Set the content size of the scrollview to the frame size of the content view. This is a very important step that people often omit.
  4. Put the scroll view in a window somewhere.

As for the paging behavior, check out UIScrollView’s pagingEnabled property. If you need to scroll by less than a whole page you’ll need to play tricks with clipsToBounds, sort of the reverse of what is happening in this StackOverflow question.

16
votes
UIScrollView *scrollview = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)]; 

NSInteger viewcount= 4; 
for (int i = 0; i <viewcount; i++) 
{ 
CGFloat y = i * self.view.frame.size.height; 
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, y,self.view.frame.size.width, self .view.frame.size.height)];      
view.backgroundColor = [UIColor greenColor]; 
[scrollview addSubview:view]; 
[view release]; 
}
scrollview.contentSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height *viewcount);

For more information Create UIScrollView programmatically

4
votes

New 3/26/2013 I stumbled on an easier way to do this without code (contentSize)

https://stackoverflow.com/a/15649607/1705353