我使用 MKAnnotationView 的自定义子类。在我的 Map 委托的 mapView:didSelectAnnotationView: 方法中，我调用了此类的方法，该方法将带有图像的 UIImageView 添加为子视图 - 它用作我的自定义注释标注。
当使用默认的 MKPinAnnotationView 地图时，地图会自动调整地图区域以显示刚刚出现的注释标注。如何使用自定义 MKAnnotationView 子类实现此行为？
【问题讨论】：
标签： ios mkmapview mkannotationview mapkit
当前解决方案
我制作了演示项目，实现了以下讨论的内容：请参阅 AdjustRegionToFitAnnotationCallout 项目。
iOS7 中 Map Kit 的 MKMapView 如何呈现地图注释的最新变化让我重新审视了这个问题。我对此进行了更准确的思考，并提出了非常非常好的解决方案。我将把之前的解决方案留在这个答案的底部，但请记住 - 当我这样做时我错了。
首先，我们需要一个帮助器CGRectTransformToContainRect()，它将给定的CGRect 扩展为包含另一个CGRect。
注意：它的行为与CGRectUnion() 的行为不同——CGRectUnion() 只返回包含CGRects 的最小CGRect，而下面的助手允许平行移动，即CGRectTransformToContainRect(CGRectMake(0, 0, 100, 100), CGRectMake(50, 50, 100, 100)) 等于(CGRect){50, 50, 100, 100} 而不是@ 987654334@ 就像CGRectUnion() 一样。当我们希望仅使用平行移动进行调整并希望避免地图缩放时，这种行为正是我们所需要的。
static inline CGRect CGRectTransformToContainRect(CGRect rectToTransform, CGRect rectToContain) {
CGFloat diff;
CGRect transformedRect = rectToTransform;
// Transformed rect dimensions should encompass the dimensions of both rects
transformedRect.size.width = MAX(CGRectGetWidth(rectToTransform), CGRectGetWidth(rectToContain));
transformedRect.size.height = MAX(CGRectGetHeight(rectToTransform), CGRectGetHeight(rectToContain));
// Comparing max X borders of both rects, adjust if
if ((diff = CGRectGetMaxX(rectToContain) - CGRectGetMaxX(transformedRect)) > 0) {
transformedRect.origin.x += diff;
}
// Comparing min X borders of both rects, adjust if
else if ((diff = CGRectGetMinX(transformedRect) - CGRectGetMinX(rectToContain)) > 0) {
transformedRect.origin.x -= diff;
}
// Comparing max Y borders of both rects, adjust if
if ((diff = CGRectGetMaxY(rectToContain) - CGRectGetMaxY(transformedRect)) > 0) {
transformedRect.origin.y += diff;
}
// Comparing min Y borders of both rects, adjust if
else if ((diff = CGRectGetMinY(transformedRect) - CGRectGetMinY(rectToContain)) > 0) {
transformedRect.origin.y -= diff;
}
return transformedRect;
}
Adjust method wrapped into an Objective-C category MKMapView(Extensions):
@implementation MKMapView (Extensions)
- (void)adjustToContainRect:(CGRect)rect usingReferenceView:(UIView *)referenceView animated:(BOOL)animated {
// I just like this assert here
NSParameterAssert(referenceView);
CGRect visibleRect = [self convertRegion:self.region toRectToView:self];
// We convert our annotation from its own coordinate system to a coodinate system of a map's top view, so we can compare it with the bounds of the map itself
CGRect annotationRect = [self convertRect:rect fromView:referenceView.superview];
// Fatten the area occupied by your annotation if you want to have a margin after adjustment
CGFloat additionalMargin = 2;
adjustedRect.origin.x -= additionalMargin;
adjustedRect.origin.y -= additionalMargin;
adjustedRect.size.width += additionalMargin * 2;
adjustedRect.size.height += additionalMargin * 2;
// This is the magic: if the map must expand its bounds to contain annotation, it will do this
CGRect adjustedRect = CGRectTransformToContainRect(visibleRect, annotationRect);
// Now we just convert adjusted rect to a coordinate region
MKCoordinateRegion adjustedRegion = [self convertRect:adjustedRect toRegionFromView:self];
// Trivial regionThatFits: sugar and final setRegion:animated: call
[self setRegion:[self regionThatFits:adjustedRegion] animated:animated];
}
@end
现在是控制器和视图：
@interface AnnotationView : MKAnnotationView
@property AnnotationCalloutView *calloutView;
@property (readonly) CGRect annotationViewWithCalloutViewFrame;
@end
@implementation AnnotationView
- (void)showCalloutBubble {
// This is a code where you create your custom annotation callout view
// add add it using -[self addSubview:]
// At the end of this method a callout view should be displayed.
}
- (CGRect)annotationViewWithCalloutViewFrame {
// Here you should adjust your annotation frame so it match itself in the moment when annotation callout is displayed and ...
return CGRectOfAdjustedAnnotation; // ...
}
@end
当在地图上选择 AnnotationView 类注解时，会将其 calloutView 添加为子视图，从而显示自定义注解标注视图。使用 MKMapViewDelegate 的方法完成：
- (void)mapView:(MapView *)mapView didSelectAnnotationView:(MKAnnotationView *)view {
// AnnotationPresenter is just a class that contains information to be displayed on callout annotation view
if ([view.annotation isKindOfClass:[AnnotationPresenter class]]) {
// Hide another annotation if it is shown
if (mapView.selectedAnnotationView != nil && [mapView.selectedAnnotationView isKindOfClass:[AnnotationView class]] && mapView.selectedAnnotationView != view) {
[mapView.selectedAnnotationView hideCalloutBubble];
}
mapView.selectedAnnotationView = view;
annotationView *annotationView = (annotationView *)view;
// This just adds *calloutView* as a subview
[annotationView showCalloutBubble];
[mapView adjustToContainRect:annotationView.annotationViewWithCalloutViewFrame usingReferenceView:annotationView animated:NO];
}
}
当然，您的实现可能与我在这里描述的不同（我的是！）。上面代码中最重要的部分当然是[MKMapView adjustToContainRect:usingReferenceView:animated: 方法。现在我对当前的解决方案和我对这个（以及一些相关的）问题的理解非常满意。如果您需要有关上述解决方案的任何 cmets，请随时与我联系（请参阅个人资料）。
以下 Apple 文档对于了解 -[MKMapView convertRect:fromView:] 等方法中发生的情况非常有用：
此外，WWDC 2013 会议的前 10-15 分钟“地图工具包的新功能”（#304）非常值得观看，以观看由 Apple 工程师完成的整个“带注释的地图”设置的出色快速演示。
初步解决方案（iOS7下不行，不要用，改用上面的解决方案）
不知怎的，我一次忘了回答我的问题。这是我现在使用的完整解决方案（为了便于阅读，稍作编辑）：
首先将一些地图逻辑封装在帮助文件中，例如 MapKit+Helpers.h
typedef struct {
CLLocationDegrees top;
CLLocationDegrees bottom;
} MKLatitudeEdgedSpan;
typedef struct {
CLLocationDegrees left;
CLLocationDegrees right;
} MKLongitudeEdgedSpan;
typedef struct {
MKLatitudeEdgedSpan latitude;
MKLongitudeEdgedSpan longitude;
} MKEdgedRegion;
MKEdgedRegion MKEdgedRegionFromCoordinateRegion(MKCoordinateRegion region) {
MKEdgedRegion edgedRegion;
float latitude = region.center.latitude;
float longitude = region.center.longitude;
float latitudeDelta = region.span.latitudeDelta;
float longitudeDelta = region.span.longitudeDelta;
edgedRegion.longitude.left = longitude - longitudeDelta / 2;
edgedRegion.longitude.right = longitude + longitudeDelta / 2;
edgedRegion.latitude.top = latitude + latitudeDelta / 2;
edgedRegion.latitude.bottom = latitude - latitudeDelta / 2;
return edgedRegion;
}
与 MKCoordinateRegion（中心坐标 + 跨度）一样，MKEdgedRegion 只是一种定义区域的方法，但使用的是其边缘的坐标。
MKEdgedRegionFromCoordinateRegion() 是一种不言自明的转换器方法。
假设我们的注释有以下类，包含它的标注作为子视图。
@interface AnnotationView : MKAnnotationView
@property AnnotationCalloutView *calloutView;
@end
当在地图上选择 AnnotationView 类注解时，会将其 calloutView 添加为子视图，从而显示自定义注解标注视图。使用 MKMapViewDelegate 的方法完成：
- (void)mapView:(MapView *)mapView didSelectAnnotationView:(MKAnnotationView *)view {
// AnnotationPresenter is just a class that contains information to be displayed on callout annotation view
if ([view.annotation isKindOfClass:[AnnotationPresenter class]]) {
// Hide another annotation if it is shown
if (mapView.selectedAnnotationView != nil && [mapView.selectedAnnotationView isKindOfClass:[AnnotationView class]] && mapView.selectedAnnotationView != view) {
[mapView.selectedAnnotationView hideCalloutBubble];
}
mapView.selectedAnnotationView = view;
annotationView *annotationView = (annotationView *)view;
// This just adds *calloutView* as a subview
[annotationView showCalloutBubble];
/* Here the trickiest piece of code goes */
/* 1. We capture _annotation's (not callout's)_ frame in its superview's (map's!) coordinate system resulting in something like (CGRect){4910547.000000, 2967852.000000, 23.000000, 28.000000} The .origin.x and .origin.y are especially important! */
CGRect annotationFrame = annotationView.frame;
/* 2. Now we need to perform an adjustment, so our frame would correspond to the annotation view's _callout view subview_ that it holds. */
annotationFrame.origin.x = annotationFrame.origin.x + ANNOTATION_CALLOUT_TRIANLE_HALF; // Mine callout view has small x offset - you should choose yours!
annotationFrame.origin.y = annotationFrame.origin.y - ANNOTATION_CALLOUT_HEIGHT / 2; // Again my custom offset.
annotationFrame.size = placeAnnotationView.calloutView.frame.size; // We can grab calloutView size directly because in its case we don't care about the coordinate system.
MKCoordinateRegion mapRegion = mapView.region;
/* 3. This was a long run before I did stop to try to pass mapView.view as an argument to _toRegionFromView_. */
/* annotationView.superView is very important - it gives us the same coordinate system that annotationFrame.origin is based. */
MKCoordinateRegion annotationRegion = [mapView convertRect:annotationFrame toRegionFromView:annotationView.superview];
/* I hope that the following MKEdgedRegion magic is self-explanatory */
MKEdgedRegion mapEdgedRegion = MKEdgedRegionFromCoordinateRegion(mapRegion);
MKEdgedRegion annotationEdgedRegion = MKEdgedRegionFromCoordinateRegion(annotationRegion);
float diff;
if ((diff = (annotationEdgedRegion.longitude.left - mapEdgedRegion.longitude.left)) < 0 ||
(diff = (annotationEdgedRegion.longitude.right - mapEdgedRegion.longitude.right)) > 0)
mapRegion.center.longitude += diff;
if ((diff = (annotationEdgedRegion.latitude.bottom - mapEdgedRegion.latitude.bottom)) < 0 ||
(diff = (annotationEdgedRegion.latitude.top - mapEdgedRegion.latitude.top)) > 0)
mapRegion.center.latitude += diff;
mapView.region = mapRegion;
}
}
【讨论】：
我一直在寻找类似的解决方案，以在屏幕的可见矩形中适应路线和标注。我尝试了一些解决方案，但最终只是在setVisibleMapRect:edgePadding:animated: 上设置了足够的填充。可能没有那么复杂，但基本上可以满足我的需要。
MKMapRect routeMapRect = myRoute.polyline.boundingMapRect;
CGFloat padding = myCallout.bounds.width / 2.0;
[myMapView setVisibleMapRect: routeMapRect edgePadding:UIEdgeInsetsMake(padding, padding, padding, padding) animated:YES];
当然，这可以更加优化，例如通过检测您实际需要填充的一侧并在另一侧设置较小的填充。但你明白了。
【讨论】：