我已经找到了如何使用关键字查找用户周围的位置。现在我的斗争是如何自动选择最近的项目，任何关于如何实现这一点的想法？谢谢，非常感谢。 `
//Map
@IBOutlet weak var map: MKMapView!
var matchingItems: [MKMapItem] = [MKMapItem]()
let manager = CLLocationManager()
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])
{
let location = locations[0]
let span:MKCoordinateSpan = MKCoordinateSpanMake(0.01, 0.01)
let myLocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)
let region:MKCoordinateRegion = MKCoordinateRegionMake(myLocation, span)
map.setRegion(region, animated: true)
matchingItems.removeAll()
let request = MKLocalSearchRequest()
request.naturalLanguageQuery = "Hopital"
request.region = map.region
let search = MKLocalSearch(request: request)
search.start(completionHandler: {(response, error) in
if error != nil {
print("Error occured in search: \(error!.localizedDescription)")
} else if response!.mapItems.count == 0 {
print("No matches found")
} else {
print("Matches found")
for item in response!.mapItems {
print("Name = \(item.name)")
print("Phone = \(item.phoneNumber)")
self.matchingItems.append(item as MKMapItem)
print("Matching items = \(self.matchingItems.count)")
let annotation = MKPointAnnotation()
annotation.coordinate = item.placemark.coordinate
annotation.title = item.name
self.map.addAnnotation(annotation)
}
}
})
self.map.showsUserLocation = true
}
编辑后的新代码，标有*
的行上的错误代码extension Array其中Iterator.Element：MKAnnotation {
func closest(to fixedLocation: CLLocation) -> Iterator.Element? {
guard !self.isEmpty else { return nil}
var closestAnnotation: Iterator.Element? = nil
var smallestDistance: CLLocationDistance = 9999999
for annotation in self {
*let locationForAnnotation = CLLocation(latitude: annotation.coordinate.latitude, longitude: annotation.coordinate.longitude)
let distanceFromUser = fixedLocation.distance(from:locationForAnnotation)
if distanceFromUser < smallestDistance {
smallestDistance = distanceFromUser
closestAnnotation = annotation
}
}
// now you can do whatever you want with the closest annotation
return closestAnnotation
}
}
并且错误显示“类型'元素'的值没有成员'坐标'
答案 0 :(得分：0)
extension Array where Iterator.Element == MKAnnotation {
func closest(to fixedLocation: CLLocation) -> Iterator.Element? {
guard !self.isEmpty else { return nil}
// create variables you'll use to track the smallest distance measured and the
// closest annotation
var closestAnnotation: Iterator.Element? = nil
var smallestDistance: CLLocationDistance = 9999999
// loop through your mapview's annotations (if you're using a different type of annotation,
// just substitude it here)
for annotation in self {
// create a location object from the coordinates for the annotation so you can easily
// compare the two locations
let locationForAnnotation = CLLocation(latitude: annotation.coordinate.latitude, longitude:annotation.coordinate.longitude)
// calculate the distance between the user's location and the location you just created
// from the annoatation's coordinates
let distanceFromUser = fixedLocation.distance(from:locationForAnnotation)
// if this calculated distance is smaller than the currently smallest distance, update the
// smallest distance thus far as well as the closest annotation
if distanceFromUser < smallestDistance {
smallestDistance = distanceFromUser
closestAnnotation = annotation
}
}
// now you can do whatever you want with the closest annotation
return closestAnnotation
}
}
sorted）extension Array where Iterator.Element == MKAnnotation {
func closest(to fixedLocation: CLLocation) -> Iterator.Element? {
return self.sorted { (annotation1, annotation2) -> Bool in
let location1 = CLLocation(latitude: annotation1.coordinate.latitude, longitude:annotation1.coordinate.longitude)
let location2 = CLLocation(latitude: annotation2.coordinate.latitude, longitude:annotation2.coordinate.longitude)
let distanceFromUser1 = fixedLocation.distance(from: location1)
let distanceFromUser2 = fixedLocation.distance(from: location2)
return distanceFromUser1 < distanceFromUser2
}.first
}
}
公用事业扩展：
extension MKMapView {
func closestAnnotationToUser() -> MKAnnotation? {
let userLoc = CLLocation(latitude: userLocation.coordinate.latitude, longitude: userLocation.coordinate.longitude)
return annotations.closest(to: userLoc)
}
}
用法：
// Works on any [MKAnnotation]
let nearestPin = self.map.annotations.closest(to: self.map.userLocation.location)
// OR
let nearestPin = self.map.closestAnnotationToUser()