从用户位置查找数组中最近的经度和纬度 - iOS Swift答案

【问题标题】：Find closest longitude and latitude in array from user location - iOS Swift从用户位置查找数组中最近的经度和纬度 - iOS Swift
【发布时间】：2018-04-23 17:22:02
【问题描述】：

在here发布的问题中，用户问：

我有一个充满经度和纬度的数组。我的用户位置有两个双重变量。我想测试我的用户位置与我的阵列之间的距离，以查看哪个位置最近。我该怎么做？

这将获得 2 个位置之间的距离，但很难理解我将如何针对一组位置进行测试。

作为回应，他得到了以下代码：

NSArray *locations = //your array of CLLocation objects
CLLocation *currentLocation = //current device Location

CLLocation *closestLocation;
CLLocationDistance smallestDistance = DBL_MAX; // set the max value

for (CLLocation *location in locations) {
    CLLocationDistance distance = [currentLocation  distanceFromLocation:location];

    if (distance < smallestDistance) {
        smallestDistance = distance;
        closestLocation = location;
    }
}
NSLog(@"smallestDistance = %f", smallestDistance);

我正在处理的应用程序中遇到完全相同的问题，我认为这段代码可以完美运行。但是，我使用的是 Swift，并且这段代码是在 Objective-C 中的。

我唯一的问题是：它在 Swift 中应该是什么样子？

感谢您的帮助。我对这一切都很陌生，在 Swift 中看到这段代码可能会大有帮助。

【问题讨论】：

标签： ios swift google-maps cllocationmanager cllocationdistance

【解决方案1】：

对于 Swift 3，我创建了这段“函数式”代码：

let coord1 = CLLocation(latitude: 52.12345, longitude: 13.54321)
let coord2 = CLLocation(latitude: 52.45678, longitude: 13.98765)
let coord3 = CLLocation(latitude: 53.45678, longitude: 13.54455)

let coordinates = [coord1, coord2, coord3]

let userLocation = CLLocation(latitude: 52.23678, longitude: 13.55555)

let closest = coordinates.min(by: 
{ $0.distance(from: userLocation) < $1.distance(from: userLocation) })

【讨论】：

【解决方案2】：

var closestLocation: CLLocation?
var smallestDistance: CLLocationDistance?

for location in locations {
  let distance = currentLocation.distanceFromLocation(location)
  if smallestDistance == nil || distance < smallestDistance {
    closestLocation = location
    smallestDistance = distance
  }
}

print("smallestDistance = \(smallestDistance)")

或作为一个函数：

func locationInLocations(locations: [CLLocation], closestToLocation location: CLLocation) -> CLLocation? {
  if locations.count == 0 {
    return nil
  }

  var closestLocation: CLLocation?
  var smallestDistance: CLLocationDistance?

  for location in locations {
    let distance = location.distanceFromLocation(location)
    if smallestDistance == nil || distance < smallestDistance {
      closestLocation = location
      smallestDistance = distance
    }
  }

  print("closestLocation: \(closestLocation), distance: \(smallestDistance)")
  return closestLocation
}

【讨论】：

现在我可以用它与Objective-C进行比较。它的帮助不止一种。谢谢！

【解决方案3】：

    func closestLoc(userLocation:CLLocation){
    var distances = [CLLocationDistance]()
    for location in locations{
        let coord = CLLocation(latitude: location.latitude!, longitude: location.longitude!)
        distances.append(coord.distance(from: userLocation))
        print("distance = \(coord.distance(from: userLocation))")
    }

    let closest = distances.min()//shortest distance
    let position = distances.index(of: closest!)//index of shortest distance
    print("closest = \(closest!), index = \(position)")
}

【讨论】：