我正在尝试缩放以适合 map 上的注释，同时锁定中心并提供一些插图。

- (void)fitAnnotations:(NSArray *)annotations edgeInsets:(UIEdgeInsets)insets
{
    CLLocationCoordinate2D originalCenter = self.centerCoordinate;
    MKMapRect mapRect = MKMapRectNull;

    for (id<MKAnnotation> annotation in annotations) {
        MKMapPoint p = MKMapPointForCoordinate([annotation coordinate]);
        mapRect = MKMapRectUnion(mapRect, MKMapRectMake(p.x, p.y, 0, 0));
    }

    mapRect = [self mapRectThatFits:mapRect edgePadding:insets];
    MKCoordinateRegion mapRegion = MKCoordinateRegionForMapRect(mapRect);

    // we now try to go back to the original center, while increasing the span by neccessary amount
    MKCoordinateSpan centeringDelta = MKCoordinateSpanMake(fabs(mapRegion.center.latitude - originalCenter.latitude), fabs(mapRegion.center.longitude - originalCenter.longitude));
    mapRegion.center = originalCenter;
    mapRegion.span.latitudeDelta += centeringDelta.latitudeDelta * 2.0;
    mapRegion.span.longitudeDelta += centeringDelta.longitudeDelta * 2.0;
    mapRegion = [self regionThatFits:mapRegion];
    [self setRegion:mapRegion animated:YES];
}

这里代码的第一部分按预期工作:它缩放以适契约(Contract)时尊重插图。但是，它会移动中心。

之后我尝试重新调整中心，但失败了。我不确定我关于重新居中的数学是否正确。

最佳答案

您的代码的第一部分计算适合注释的边界映射 rect 是可以的。

只需要更正“最小” map 矩形以使“锁定”中心实际上位于中心的调整。

我认为，主要问题是问题中的代码正在调整跨度，以便在调用 mapRectThatFits: 后重新居中区域并考虑插入:(它本身已经给出您实际请求的 rect 的略微修改版本)。

相反，您的代码应该只计算它想要 的实际最小矩形，然后然后 最终调用setVisibleMapRect:edgePadding:animated: 并让 map View 找出“适合的矩形”和插图。

请尝试以下操作:

- (void)fitAnnotations:(NSArray *)annotations edgeInsets:(UIEdgeInsets)insets
{
    MKMapPoint centerMapPoint = MKMapPointForCoordinate(originalCenter);

    //--- First create minimal bounding map rect to tightly fit annotations...
    MKMapRect minimalMapRect = MKMapRectNull;

    for (id<MKAnnotation> annotation in annotations) {
        MKMapPoint annMapPoint = MKMapPointForCoordinate(annotation.coordinate);
        minimalMapRect = MKMapRectUnion(minimalMapRect, MKMapRectMake(annMapPoint.x, annMapPoint.y, 0, 0));
    }


    //--- Now create adjusted map rect so center coordinate is in the center...

    //distance of desired center from minimal left edge...
    double centerXOffset = centerMapPoint.x - minimalMapRect.origin.x;

    //raw amount width needs to be adjusted to get center in center...
    //negative/positive indicates whether center is in left/right half
    double widthOffset = 2.0 * centerXOffset - minimalMapRect.size.width;

    //add absolute value of raw width offset to minimal width...
    double adjustedWidth = minimalMapRect.size.width + fabs(widthOffset);

    //distance of desired center from minimal top edge...
    double centerYOffset = centerMapPoint.y - minimalMapRect.origin.y;

    //raw amount height needs to be adjusted to get center in center...
    //negative/positive indicates whether center is in top/bottom half
    double heightOffset = 2.0 * centerYOffset - minimalMapRect.size.height;

    //add absolute value of raw height offset to minimal height...
    double adjustedHeight = minimalMapRect.size.height + fabs(heightOffset);

    //adjust origin if necessary (if center is in top/left half)...
    MKMapPoint adjustedOrigin = minimalMapRect.origin;
    if ((centerXOffset / minimalMapRect.size.width) < 0.5)
    {
        adjustedOrigin.x = adjustedOrigin.x + widthOffset;
    }
    if ((centerYOffset / minimalMapRect.size.height) < 0.5)
    {
        adjustedOrigin.y = adjustedOrigin.y + heightOffset;
    }

    //create adjusted MKMapRect...
    MKMapRect adjustedMapRect = MKMapRectMake(adjustedOrigin.x, adjustedOrigin.y, adjustedWidth, adjustedHeight);


    //--- Apply the adjusted map rect with insets to map view...
    [mapView setVisibleMapRect:adjustedMapRect edgePadding:insets animated:YES];
}

关于ios - MKMapView 缩放以在锁定中心时适合注释，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/29947643/