如何调整区域以适应刚刚出现的自定义注释标注？

Question

我使用MKAnnotationView的自定义子类.在mapView:didSelectAnnotationView:我的Map委托的方法我调用这个类的方法,它将UIImageView与图像作为子视图添加 - 它作为我的自定义注释标注.

当使用默认的MKPinAnnotationView地图时,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？

Answer 1

当前解决方案

我已经制作了具有下面讨论的内容的演示项目:参见 AdjustRegionToFitAnnotationCallout项目.

Map Kit的MKMapView渲染地图注释的最新iOS7变化让我重新审视了这个问题.我已经对它做了更准确的思考,并提出了更好,更好的解决方案.我将把上一个解决方案留在这个答案的底部,但请记住 - 当我这样做的时候,我错了.

首先,我们需要一个CGRectTransformToContainRect()扩展给定CGRect的包含另一个的帮助器CGRect.

注意:它的行为不同于CGRectUnion()- CGRectUnion()只返回CGRect包含两者的最小值CGRects,而后面的帮助器允许平行移动,即CGRectTransformToContainRect(CGRectMake(0, 0, 100, 100), CGRectMake(50, 50, 100, 100))等于(CGRect){50, 50, 100, 100}而不是(CGRect){0, 0, 150, 150}像CGRectUnion()它一样.当我们想要仅使用平行移动进行调整并且想要避免地图的缩放时,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

在地图上选择AnnotationView分类注释时,它会将其calloutView添加为子视图,因此会显示自定义注释标注视图.它是使用MKMapViewDelegate的方法完成的:

- (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,你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.如果您对上述解决方案有任何意见,请随时与我联系(参见个人资料).

以下Apple文档对于理解诸如 - [MKMapView convertRect:fromView:]等方法的内容非常有用:

http://developer.apple.com/library/ios/#documentation/MapKit/Reference/MKMapView_Class/MKMapView/MKMapView.html

http://developer.apple.com/library/ios/#documentation/MapKit/Reference/MapKitDataTypesReference/Reference/reference.html

http://developer.apple.com/library/ios/#documentation/MapKit/Reference/MapKitFunctionsReference/Reference/reference.html

此外,WWDC 2013会议的前10-15分钟"Map Kit中的新功能"(#304)非常适合观看Apple工程师完成的整个"带注释的地图"设置的精彩快速演示.

初始解决方案(在iOS7中不起作用,不要使用它,请使用上面的解决方案)

不知怎的,我忘了一次回答我的问题.这是我现在使用的完整解决方案(为了便于阅读,略微编辑):

首先,将一些映射逻辑封装在帮助器文件中的某个位置,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只是一种定义区域但使用其边缘坐标的方法.

MKEdgedRegionFromCoordinateRegion()是一个不言自明的转换器方法.

假设我们的注释有以下类,包含其标注作为子视图.

@interface AnnotationView : MKAnnotationView
@property AnnotationCalloutView *calloutView;
@end

在地图上选择AnnotationView分类注释时,它会将其calloutView添加为子视图,因此会显示自定义注释标注视图.它是使用MKMapViewDelegate的方法完成的:

- (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;
    }
}