我正在创建一个用于显示时间轴的控件。最初，应该显示年份。当缩放至zoomScale到达特定值时，它将显示每个月份的值，在下一个缩放级别中，它应该显示每个独立日的实际值。
我已经创建了一个scrollview，并将layers（用于显示月/年值）添加到其中。在覆盖收缩手势后，我能够进行缩放（基本的UIScrollview缩放）。但我需要将其缩放到特定点。即，假设我正在缩放一月份，则需要保持它在相同的位置（以创建类似于在一月份内移动的效果）。有什么建议可以实现这一点吗？
我的方式正确吗？否则，请帮我开始这个项目。
- (void)zoomToRect:(CGRect)rect animated:(BOOL)animated
只需使用您选择的框架或点来调用上述方法，例如如果选择了一月，则只需获取一月按钮或视图的位置并使用该框架调用上述方法。
如需更多信息，请参见此链接：UIScrollView_Class
希望这对您有所帮助...
@implementation UIScrollView (ZoomToPoint)
- (void)zoomToPoint:(CGPoint)zoomPoint withScale: (CGFloat)scale animated: (BOOL)animated
{
//Normalize current content size back to content scale of 1.0f
CGSize contentSize;
contentSize.width = (self.contentSize.width / self.zoomScale);
contentSize.height = (self.contentSize.height / self.zoomScale);
//translate the zoom point to relative to the content rect
zoomPoint.x = (zoomPoint.x / self.bounds.size.width) * contentSize.width;
zoomPoint.y = (zoomPoint.y / self.bounds.size.height) * contentSize.height;
//derive the size of the region to zoom to
CGSize zoomSize;
zoomSize.width = self.bounds.size.width / scale;
zoomSize.height = self.bounds.size.height / scale;
//offset the zoom rect so the actual zoom point is in the middle of the rectangle
CGRect zoomRect;
zoomRect.origin.x = zoomPoint.x - zoomSize.width / 2.0f;
zoomRect.origin.y = zoomPoint.y - zoomSize.height / 2.0f;
zoomRect.size.width = zoomSize.width;
zoomRect.size.height = zoomSize.height;
//apply the resize
[self zoomToRect: zoomRect animated: animated];
}
@end
看起来，应该很容易就能理解它的工作原理。如果你发现有什么问题，请在评论中告诉我。
谢谢 :)
来源: http://www.tim-oliver.com/2012/01/14/zooming-to-a-point-in-uiscrollview/
[self.scrollViewForMap setZoomScale:2.0 animated:YES]; //for zooming
_scrollViewForMap.contentOffset = CGPointMake(500,300); //for location
- (void)pinchDetected:(UIPinchGestureRecognizer *)gestureRecognizer {
if([gestureRecognizer state] == UIGestureRecognizerStateBegan) {
// Reset the last scale, necessary if there are multiple objects with different scales
lastScale = [gestureRecognizer scale];
}
if ([gestureRecognizer state] == UIGestureRecognizerStateBegan ||
[gestureRecognizer state] == UIGestureRecognizerStateChanged) {
CGFloat currentScale = [[[gestureRecognizer view].layer valueForKeyPath:@"transform.scale"] floatValue];
// Constants to adjust the max/min values of zoom
const CGFloat kMaxScale = 2.2;
const CGFloat kMinScale = 0.64;
CGFloat newScale = 1 - (lastScale - [gestureRecognizer scale]);
newScale = MIN(newScale, kMaxScale / currentScale);
newScale = MAX(newScale, kMinScale / currentScale);
CGAffineTransform transform = CGAffineTransformScale([[gestureRecognizer view] transform], newScale, newScale);
[gestureRecognizer view].transform = transform;
[gestureRecognizer setScale:1.0];
lastScale = [gestureRecognizer scale]; // Store the previous scale factor for the next pinch gesture call
}
}
对我有效的方法（Swift 4）：
func zoomIn(with gestureRecognizer: UIGestureRecognizer?) {
guard let location = gestureRecognizer?.location(in: gestureRecognizer?.view)
let rect = CGRect(x: location.x, y: location.y, width: 0, height: 0)
scrollView.zoom(to: rect, animated: true)
}
CGRect将导致UIScrollView在maximumZoomScale下缩放到矩形的origin。
-zoomToRect:animated:方法呢？ - holex