How do you zoom a UIScrollView's content to fit

My UIScrollView on the iPhone is 480x230 and the content is 972x230 when first displayed. I need to provide functionality where when the user double taps the UIScrollView the contents zoom to fit with the 480x230 UIScrollView proportionally. When the double tap it again it should zoom back out to it's original size.

What is the best way to do this? I have been fumbling for several hours with this and thought that this would work...

[bodyClockScrollView zoomToRect:bodyClockScroll开发者_JAVA技巧View.frame animated:YES];

But nothing seems to happen.

Thanks, any help pointing me in the right direction would be appreciated.

You need to make sure the class you've set up as the scrollview's delegate implements this method:

-(UIView *) viewForZoomingInScrollView:(UIScrollView *)scrollView {
return someView;

}

Using CGAffineTransform I figured out a way to do what I want...

    //bodyCleckScrollView contains a UIView name bodyClock
    //get the scale factor required to fit bodyClock inside the iPhone window and resize it...
    CGFloat scale = 480/bodyClockScrollView.contentSize.width;  
    bodyClock.transform = CGAffineTransformScale(bodyClock.transform, scale, scale);
    //move bodyClock to the bottom of bodyScrollView.
    bodyClock.transform = CGAffineTransformTranslate(bodyClock.transform, 0.0,bodyClockScrollView.frame.size.height-bodyClock.frame.size.height);
    //scoll bodyScrollView so that bodyClock is centered in the window 
    CGPoint offsetPoint = CGPointMake(bodyClock.frame.origin.x, 0.0);
    [bodyClockScrollView setContentOffset:offsetPoint animated:YES];   

This works great and when I want to zoom it back out to the default size and position you simply call...

    bodyClock.transform = CGAffineTransformIdentity;