双击放大是 iPhone 的一个基本操作，第三方程序里引入这一功能的话，主要是在 scrollview 呈现一张图片或者 PDF 页面时，双击可以放大，主要代码如下
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{
NSLog(@"%s", _cmd);
CGFloat zs = scrollView.zoomScale;
zs = MAX(zs, 0.1);
zs = MIN(zs, 5.0);
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.3];
scrollView.zoomScale = zs;
[UIView commitAnimations];
}
#pragma mark -
#pragma mark === UITouch Delegate ===
#pragma mark -
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
//NSLog(@"%s", _cmd);
UITouch *touch = [touches anyObject];
if ([touch tapCount] == 2)
{
//NSLog(@"double click");
CGFloat zs = self.zoomScale;
zs = (zs == 1.0) ? 2.0 : 1.0;
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.3];
self.zoomScale = zs;
[UIView commitAnimations];
}
}