在Swift

Question

我正在尝试传递我从Firebase数据库中读取的变量。

    func annotatemyMap() {

    let refx = Database.database().reference().child("child").child("child").child("child").child("LocX")
    ref.observeSingleEvent(of: .value, with: { (snapshot) in
        let locX = snapshot.value as! Double
    })

    let refy = Database.database().reference().child("child").child("child").child("child").child("LocY")
    refy.observeSingleEvent(of: .value, with: { (snapshot) in
        let LocY = snapshot.value as! Double
    })

    point.coordinate = CLLocationCoordinate2DMake(locX , locY)
    //REST OF MY FUNCTIONS CODE........

}

point.coordinate中的locX和locY为零。我理解为什么，但我无法弄清楚如何将locX和locY传递给point.coordinate。

问题：如何将loxX和locY的值（从firebase读取）传递给point.coordinate。

Answer 1

您可以尝试嵌套调用或使用完成

let refx = Database.database().reference().child("child").child("child").child("child").child("LocX")
ref.observeSingleEvent(of: .value, with: { (snapshot) in
    let locX = snapshot.value as! Double

      let refy = Database.database().reference().child("child").child("child").child("child").child("LocY")
      refy.observeSingleEvent(of: .value, with: { (snapshot) in
       let LocY = snapshot.value as! Double

         point.coordinate = CLLocationCoordinate2DMake(locX , locY)
        //REST OF MY FUNCTIONS CODE........

     })

})