iOS地图 mapView.region.span.latitudedelta 属性

最新推荐文章于 2021-02-28 13:17:14 发布

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最新推荐文章于 2021-02-28 13:17:14 发布

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文章标签： python

原文链接：https://my.oschina.net/u/728866/blog/123940

本文探讨了如何在移动应用中有效限制地图的显示范围，并针对MKCoordinateSpan结构的应用进行了深入研究。作者通过实验发现，随着地图上下拖动，latitudeDelta而非longitudeDelta发生变化，且在接近两极时该值减小。

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应客户要求需要限制地图的显示范围，但因了解不深，所以效果总是不理想。终小有体会，留记以醒。

先看官方文档：

MKCoordinateSpan

A structure that defines the area spanned by a map region.

typedef struct {

   CLLocationDegrees latitudeDelta;

   CLLocationDegrees longitudeDelta;

} MKCoordinateSpan;

Fields

latitudeDelta

The amount of north-to-south distance (measured in degrees) to display on the map. Unlike longitudinal distances, which vary based on the latitude, one degree of latitude is always approximately 111 kilometers (69 miles).

longitudeDelta

The amount of east-to-west distance (measured in degrees) to display for the map region. The number of kilometers spanned by a longitude range varies based on the current latitude. For example, one degree of longitude spans a distance of approximately 111 kilometers (69 miles) at the equator but shrinks to 0 kilometers at the poles.

Discussion

You use the delta values in this structure to indicate the desired zoom level of the map, with smaller delta values corresponding to a higher zoom level.

Availability