Question

我正在尝试在基于View的应用程序中部署以下代码，但在尝试运行时遇到以下错误：

GPSViewController.h

CLLocationManager *lm;
CLLocation *firstLocation;
CLLocation *secondLocation;
CLLocationDistance *distance;
NSString *distanceString;

GPSViewController.m

firstLocation = [[[CLLocation alloc] initWithLatitude:lat1 longitude:lon1] autorelease];
secondLocation = [[[CLLocation alloc] initWithLatitude:lat2 longitude:lon2] autorelease];
distance = [secondLocation distanceFromLocation:firstLocation]; //CLLocation may not respond to distanceFromLocation

double dist = distance / 1000;  //invalid operands to binary

distanceString = [[NSString alloc] stringWithFormat: @"%f", dist];
NSLog(@"the distance between the two points is: %@", distanceString);

在上面的示例代码中，如何将变量“distance”从“CLLocationDistance”类型转换为“double”类型？

我只是尝试使用两个不同的CLLocation对象计算两点之间的距离，然后将其打印到控制台。 lat1，lon1，lat2，lon2是双打。

谁能看到我哪里出错了？

Answer 1

CLLocationDistance是一个双精度数，因此您无需尝试转换为double或其他任何内容。

你可以像这样计算你的数据，它会起作用：

CLLocationDistance distance = [secondLocation distanceFromLocation:firstLocation];  // distance is expressed in meters

CLLocationDistance kilometers = distance / 1000.0;
NSString *distanceString = [[NSString alloc] initWithFormat: @"%f", kilometers];

需要帮助调试CLLocation代码以找到两点之间的距离

1 个答案: