UIScrollview使当前图像变大

Question

I am building a scrollable gallery with 10 images. When I stop on an image, I want the current image to look little taller than the other ones on either side. How do I get the view in focus and adjust the frame ? Once the drag ends, the function scrollViewDidEndDecelerating gets called. How do I get the reference to that imageview's frame ?

Answer 1

Let's say that you hold reference to the UIImageView s in self.imageViews , you can try something like this.

CGFloat centerX = CGRectGetMidX(self.view.bounds);
for(UIImageView imgView * in self.imageViews)
{
    if(CGRectContainsPoint(imgView, centerX)) // If imgView is close to center
    {
        imgView.transform = CGAffineTransformMakeScale(1.2f, 1.2f);
    }
    else
    {
        imgView.transform = CGAffineTransformIdentity;
    }
}

I assumed you are scrolling horizontally, but if you are doing it vertically, you need to use centerY instead.

Answer 2

查看iCarousel，而不是重新发明轮子。... https://github.com/nicklockwood/iCarousel

Answer 3

If your list of images is finite, and won't get too large, I'd keep an NSArray of references to the images. Then, in scrollViewDidEndDecelerating you can use the scroll offset to determine where the scrolling stopped, and put that in proportion to the whole view, and you should be able to tell which index'd image in the array to show.

Something like this (syntax might be off)

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    //assumes that "arrayOfImages" is the array of images that you are showing
    //contentOffset.y assumes your scroll view is scrolling vertically, switch to x if horizontal
    int indexOfImageToShow = scrollView.contentOffset.y / [arrayOfImages count];
    UIImage *imageToShow = [arrayOfImages objectAtIndex:indexOfImageToShow];
}