swift - 多字符串变量数组 swift

Question

我有两个数组，我想将这些数组收集为一个数组。所以我想做的是拥有

gradepickervalues 1 + gradepickervalues 2 + gradepickervalues 3 = gradePickerValues

我该怎么办？它现在在代码中不起作用。

 var picker = UIPickerView()

    var gradePickerValues1 = [String]()
    var gradePickerValues2 = [String]()
    var gradePickerValues3 = [String]()
    var gradePickerValues = [String]()

    @objc func GetDevice() {


        if !chipnumber.text!.isEmpty {
            let ref = Database.database().reference().child(chipnumber.text!).child("titles").child("0").child("DeviceName")

            ref.observeSingleEvent(of: .value, with: { (snapshot) in
                //let value: NSDictionary = snapshot.value as! NSDictionary
                let dic = snapshot.value as! String
                self.gradePickerValues = [dic]
            })

        }

        if !chipnumber2.text!.isEmpty {
            let ref = Database.database().reference().child(chipnumber2.text!).child("titles").child("0").child("DeviceName")

            ref.observeSingleEvent(of: .value, with: { (snapshot) in
                //let value: NSDictionary = snapshot.value as! NSDictionary
                let dic = snapshot.value as! String
                self.gradePickerValues = [dic]

            })

        }

        if !chipnumber3.text!.isEmpty {
            let ref = Database.database().reference().child(chipnumber3.text!).child("titles").child("0").child("DeviceName")

            ref.observeSingleEvent(of: .value, with: { (snapshot) in
                //let value: NSDictionary = snapshot.value as! NSDictionary
                let dic = snapshot.value as! String
                self.gradePickerValues = [dic]

            })

        }

    }

Answer 1

目前您在每个响应中都覆盖了gradePickerValues，您可以尝试使用

var picker = UIPickerView() 
var gradePickerValues1 = [String]()
var gradePickerValues2 = [String]()
var gradePickerValues3 = [String]()
var gradePickerValues = [String]()

let g = DispatchGroup()

@objc func GetDevice() {



    if !chipnumber.text!.isEmpty {

        g.enter()

        let ref = Database.database().reference().child(chipnumber.text!).child("titles").child("0").child("DeviceName")

        ref.observeSingleEvent(of: .value, with: { (snapshot) in
            //let value: NSDictionary = snapshot.value as! NSDictionary
            let dic = snapshot.value as! String
            self.gradePickerValues1 = [dic]
            self.g.leave()
        })

    }

    if !chipnumber2.text!.isEmpty {

        g.enter()

        let ref = Database.database().reference().child(chipnumber2.text!).child("titles").child("0").child("DeviceName")

        ref.observeSingleEvent(of: .value, with: { (snapshot) in
            //let value: NSDictionary = snapshot.value as! NSDictionary
            let dic = snapshot.value as! String
            self.gradePickerValues2 = [dic]
            self.g.leave()
        })

    }

    if !chipnumber3.text!.isEmpty {

        g.enter()

        let ref = Database.database().reference().child(chipnumber3.text!).child("titles").child("0").child("DeviceName")

        ref.observeSingleEvent(of: .value, with: { (snapshot) in
            //let value: NSDictionary = snapshot.value as! NSDictionary
            let dic = snapshot.value as! String
            self.gradePickerValues3 = [dic]
            self.g.leave()

        })

    }

    g.notify(queue:.main) {

        self.gradePickerValues = gradePickerValues1 + gradePickerValues2 + gradePickerValues3

        print(self.gradePickerValues)
    }

}