计算Swift中两个CLLocation点之间的方位 [英] Calculating bearing between two CLLocation points in Swift

问题描述

我正在尝试计算仅限swift的代码中两个CLLocation点之间的方位。我遇到了一些困难，并假设这是一个非常简单的功能。堆栈溢出似乎没有列出任何内容。

I'm trying to calculate a bearing between two CLLocation points in swift-only code. I've run into some difficulty and was assuming this is a pretty simple function. Stack overflow didn't seem to have anything listed.

func d2r(degrees : Double) -> Double {
    return degrees * M_PI / 180.0
}

func RadiansToDegrees(radians : Double) -> Double {
    return radians * 180.0 / M_PI
}


func getBearing(fromLoc : CLLocation, toLoc : CLLocation) {

    let fLat = d2r(fromLoc.coordinate.latitude)
    let fLng = d2r(fromLoc.coordinate.longitude)
    let tLat = d2r(toLoc.coordinate.latitude)
    let tLng = d2r(toLoc.coordinate.longitude)

    var a = CGFloat(sin(fLng-tLng)*cos(tLat));
    var b = CGFloat(cos(fLat)*sin(tLat)-sin(fLat)*cos(tLat)*cos(fLng-tLng))

    return atan2(a,b)
}

我的atan2调用有关lvalue cgfloat或其他什么的错误...

I'm getting an error with my atan2 call about lvalue cgfloat or something...

推荐答案

这是一个Objective-C解决方案

Here is an Objective-C solution

• 用于计算轴承w / Haversine功能的CLLocation类别

• CLLocation Category for Calculating Bearing w/ Haversine function

可轻松转换为Swift：

which can easily be translated to Swift:

func degreesToRadians(degrees: Double) -> Double { return degrees * .pi / 180.0 }
func radiansToDegrees(radians: Double) -> Double { return radians * 180.0 / .pi }

func getBearingBetweenTwoPoints1(point1 : CLLocation, point2 : CLLocation) -> Double {

    let lat1 = degreesToRadians(degrees: point1.coordinate.latitude)
    let lon1 = degreesToRadians(degrees: point1.coordinate.longitude)

    let lat2 = degreesToRadians(degrees: point2.coordinate.latitude)
    let lon2 = degreesToRadians(degrees: point2.coordinate.longitude)

    let dLon = lon2 - lon1

    let y = sin(dLon) * cos(lat2)
    let x = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLon)
    let radiansBearing = atan2(y, x)

    return radiansToDegrees(radians: radiansBearing)
}

结果类型是 Double 因为这是所有位置坐标都是
存储的方式（ CLLocationDegrees 是 Double 的类型别名。

The result type is Double because that is how all location coordinates are stored (CLLocationDegrees is a type alias for Double).

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