如何獲得一個點的經緯度？

Question

我是iPhone開發者的新手。我正在設計一個項目，我已經給出了起點和終點地址。假設我在這些點之間的距離是100英里，我分成五個相等的20英里。那麼從起點開始距離20英里的距離如何呢？

Answer 1

此功能添加到您的類：

// position is a number between 0 and 1, where 0 gives the start position, and 1 gives the end position 
- (CLLocationCoordinate2D)pointBetweenStartPoint:(CLLocationCoordinate2D)startPoint endPoint:(CLLocationCoordinate2D)endPoint position:(float)position { 

    CLLocationDegrees latSpan = endPoint.latitude - startPoint.latitude; 
    CLLocationDegrees longSpan = endPoint.longitude - startPoint.longitude; 

    CLLocationCoordinate2D ret = CLLocationCoordinate2DMake(startPoint.latitude + latSpan*position, 
                  startPoint.longitude + longSpan*position); 

    return ret; 
} 

然後，您可以使用此方法是這樣的（假設你想要的距離分成5）：

CLLocationCoordinate2D startPoint = CLLocationCoordinate2DMake(/* lat, long of start point */); 
CLLocationCoordinate2D endPoint = CLLocationCoordinate2DMake(/* lat, long of end point */); 

for (int i = 1; i < 5; i++) { 
    float position = i/5.0; 
    CLLocationCoordinate2D middlePosition = [self pointBetweenStartPoint:startPoint endPoint:endPoint position:position]; 
    NSLog("%f, %f", middlePosition.latitude, middlePosition.longitude); 
}