iphone - distanceFromLocation似乎不起作用

在应用程序中，我需要计算两点之间的距离。我就是这样

- (void)locationManager:(CLLocationManager *)manager
    didUpdateToLocation:(CLLocation *)newLocation
           fromLocation:(CLLocation *)oldLocation{
    NSLog(@"updating");
     //Getting my concerts
    arrConcerten = [matches mutableCopy];

       for (Event *concert in arrConcerten) {
            CLLocation *restaurnatLoc = [[CLLocation alloc] initWithLatitude:[concert.eve_latitude floatValue] longitude:[concert.eve_longitude floatValue]];

            CLLocationDistance meters = [restaurnatLoc distanceFromLocation:newLocation];
            NSLog(@"meters are %f",meters);
            if(meters > 5000){
                [locationManager2 stopUpdatingLocation];
                NSString *message2 = [NSString stringWithFormat:@"Long = %f and lat= %f and Concert Lat = %f and long = %f",newLocation.coordinate.longitude,newLocation.coordinate.latitude,[concert.eve_latitude floatValue],[concert.eve_longitude floatValue]];
                NSLog(@"%@",message2);
            }else{

                NSLog(@"too far away");
            }

        }
    }

这就是我的日志所说的。

2013-10-17 15:57:23.518 Domino[7468:907] meters are 7973.753294
2013-10-17 15:57:23.520 Domino[7468:907] Long = 5.621456 and lat= 51.097340 and Concert Lat = 51.038139 and long = 5.557330
2013-10-17 15:57:23.896 Domino[7468:907] meters are 27850.874245
2013-10-17 15:57:23.899 Domino[7468:907] Long = 5.621456 and lat= 51.097340 and Concert Lat = 50.860332 and long = 5.493722

如您所见，这些位置彼此靠近。但它仍然表示我们相距太远。有人可以帮我吗？

最佳答案

您为什么使用此：

如果超过5000米：做点什么，否则距离太远？我不明白逻辑。如果距离太远，则超过5000米。所以我认为：

  - (void)locationManager:(CLLocationManager *)manager
        didUpdateToLocation:(CLLocation *)newLocation
               fromLocation:(CLLocation *)oldLocation{
        NSLog(@"updating");
         //Getting my concerts
        arrConcerten = [matches mutableCopy];

       for (Event *concert in arrConcerten) {
            CLLocation *restaurnatLoc = [[CLLocation alloc] initWithLatitude:[concert.eve_latitude floatValue] longitude:[concert.eve_longitude floatValue]];

            CLLocationDistance meters = [restaurnatLoc distanceFromLocation:newLocation];
            NSLog(@"meters are %f",meters);
            if(meters <= 5000){
                [locationManager2 stopUpdatingLocation];
                NSString *message2 = [NSString stringWithFormat:@"Long = %f and lat= %f and Concert Lat = %f and long = %f",newLocation.coordinate.longitude,newLocation.coordinate.latitude,[concert.eve_latitude floatValue],[concert.eve_longitude floatValue]];
                NSLog(@"%@",message2);
            }else{

                NSLog(@"too far away");
            }

        }
    }

或不恰当：

if(meters > 5000){

                    NSLog(@"it's far enough");
 }else{

                    NSLog(@"too close");
 }

还有一件非常重要的事情：


  该方法通过跟踪来测量两个位置之间的距离
  它们之间的一条线跟随地球的曲率。的
  产生的圆弧是平滑曲线，未考虑在内
  两个位置之间的特定高度变化。
  来自apple documentation


distanceFromLocation测量“空中”的距离，而不是逐圈测量。

关于iphone - distanceFromLocation似乎不起作用，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/19428832/