根据位置半径过滤Firebase数据库

Question

我有以下Firebase数据库结构,

"-KSupX7CppMD1zbqIy0y" : {
  "addedByUser" : "zQpb7o18VzYsSoTQtT9DNhOqTUn2",
  "content" : "Post 1",
  "cost" : "20",
  "duration" : "Weekly",
  "latitude" : "40.7594479995956",
  "longitude" : "-73.9838934062393",
  "timestamp" : "Fri 30 Sep"
},
"-KSuphuqO6a0lnrJYUkt" : {
  "addedByUser" : "zQpb7o18VzYsSoTQtT9DNhOqTUn2",
  "content" : "Post 2",
  "cost" : "10",
  "duration" : "Daily",
  "latitude" : "40.7594329996462",
  "longitude" : "-73.9846261181847",
  "timestamp" : "Fri 30 Sep"
}

我需要在一定的距离参数(小于50米,100米,150米和200米)内过滤帖子.我可以从"经度"和"纬度"获得坐标,但我很难过滤帖子.任何帮助将不胜感激.

提前谢谢了.新手到Firebase和Swift.

Answer 1

以下是您可以尝试的解决方案。这假设您已将所有帖子从 Firebase 下载到应用程序并存储在数组中。您还可以考虑使用我个人没有使用过的 GeoFire（但愿意）。我相信它允许您按位置查询 Firebase，因此您不必首先将所有帖子下载到用户的设备并在客户端进行过滤。

// assumes you have set up the app to get the user's current location
var currentLocation: CLLocation?

// Your array of posts downloaded from Firebase
var postArray = [post]()

let metersInTwentyFiveMiles = 40233.6

// You could put this in viewDidAppear after you load the post array from Firebase
for post in postArray {

    var distanceInMeters: CLLocationDistance = 0

    let postLocation = CLLocation(latitude: post.latitude, longitude: post.longitude)


    if let currentLocation = self.currentLocation {
         // Set distanceInMeters to the distance between the user's current location and the location of the post.
         distanceInMeters = currentLocation.distanceFromLocation(postLocation)
         // If this distance is not within 25 miles, remove this post from the array
         if self.metersInTwentyFiveMiles < distanceInMeters {
            self.posts = self.posts.filter{ $0 != post }
       }
    }
}