通过纬度和经度吸引特定半径的用户 [英] Get users from certain radius by latitude and longitude

问题描述

我已在Firebase Firestore中为每个用户指定了经度和纬度的位置坐标.我只想按用户在特定半径内的坐标查询.例如50公里.如果我只知道每个用户的纬度和经度，怎么办?

I've locations coordinates in Firebase Firestore for each user with latitude and longitude. I want to query only users by their coordinates in certain radius. For example, 50km. How this can be done if I know only latitude and longitude for each user?

推荐答案

    let userLocation = CLLocation(latitude: 6.0, longitude: 6.0)
    
    let coordinate1 = CLLocation(latitude: 6.1, longitude: 6.1)
    let coordinate2 = CLLocation(latitude: 5.0, longitude: 3.0)
    let coordinate3 = CLLocation(latitude: 7.0, longitude: 3.0)
    
    let coordinatesArray = [coordinate1, coordinate2, coordinate3]
    
    for coordinate in coordinatesArray {
        if userLocation.distance(from: coordinate) < 50000 {
            print("Inside 50 km")
        }
    }

请注意， distance(from:)方法以米为单位，这就是为什么我要检查它是否在 50000m(50km)之内.应该在坐标1上执行打印语句，因为它距 15.6 km .

Note that distance(from:) method is measured in meters, thats why I am checking if it is inside 50000m(50km). Print statement should be executed for coordinate1 because it is 15.6 km away.

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