iPhone指南针显示到特定位置 [英] iPhone compass showing to a specific location

问题描述

我是Objective-c的新手，所以如果我的问题太垃圾，我想道歉。

I am new to objective-c so I want to apologize if my question is too rubbish.

我正在编程指南针然而，它正在工作（谢谢到教程）。
给出实际位置（经度和纬度）。
罗盘内的箭头是否可以显示指向特定位置（经度2和纬度2）的方向？
我读过我必须考虑iphone的磁性和真实标题。

I am programming a compass and yet, it is working (thanks to a tutorial). Actual position (Longitude and Lattitude) is given. Is it possible that my arrow within the compass can show me the direction to a specific location (longitude2 and lattitude2)? I have read that I have to consider the magnetic and the true heading of the iphone.

推荐答案

- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading {
    double heading = newHeading.trueHeading; //in degree relative to true north
    double bearing = ... //get current bearing in degree relative to true north
                         //with the JS library mentioned below it would be something like
                         //bearing = userLoc.bearingTo(destionation);

    //just two lines, the the sake of the example
    double rotationInDegree = (bearing - heading);  //the important line
    rotationInDegree = fmod((rotationInDegree + 360), 360);  //just to be on the safe side :-)
    compassViewPerhapsAsImage.transform=CGAffineTransformMakeRotation(DegreesToRadians(rotationInDegree));
}

计算方位的好链接：

• http：// www。 moving-type.co.uk/scripts/latlong.html 与eplanations和Javascript示例，但很容易转换！ ： - ）


• https://github.com/tadelv/CLLocation -Bearing as Objective C Project

• http://www.movable-type.co.uk/scripts/latlong.html with eplanations and Javascript exampless, but very easy to convert! :-)
• https://github.com/tadelv/CLLocation-Bearing as Objective C Project

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