相关疑难解决方法(0)

我正在尝试为应用程序开发一个指南针,它在地图上有一组注释.我希望能够选择一个注释,然后让指南针将用户指向所选位置.

我已经计算了从用户位置到注释位置的degress,我有磁性标题和iPhone的真实标题.我也知道如何旋转图像.但我无法弄清楚下一步是什么.

用户位置和注释位置之间的度数计算如下:

    // get user location
    locationManager = [[CLLocationManager alloc] init];
    locationManager.delegate = self; 
    locationManager.desiredAccuracy = kCLLocationAccuracyBest; 
    locationManager.distanceFilter = kCLDistanceFilterNone; 
    [locationManager startUpdatingLocation];
    [locationManager startUpdatingHeading];
    CLLocation *location = [locationManager location];
    CLLocationCoordinate2D coordinate = [location coordinate];

    float x1 = coordinate.latitude;
    float y1 = coordinate.longitude;
    float x2 = [annLatitude floatValue];
    float y2 = [annLongitude floatValue];

    float dx = (x2 - x1);
    float dy = (y2 - y1);

    if (dx == 0) {
        if (dy > 0) {
            result = 90;
        }
        else …