Question

我收到的错误是无法将'FIRDataSnapshot'类型的值转换为'NSString'。检索名称或检索数量/制造商都不起作用。两者都给出了相同的铸造误差。

ref = Database.database().reference()

    // Retrieve Names

    ref.child("rawMaterials").observeSingleEvent(of: .value, with: { (snapshot) in
        for child in snapshot.children {
            self.rawMaterialNames.append(child as! String)
        }
    })
    //Retrieve Quantities and Manfacturers

    for name in rawMaterialNames {
        ref.child("rawMaterials/\(name)").observe(.value, with: { (snapshot) in
            if let data = snapshot.value as? [String: Any] {
                for i in data {
                    let quantity = data["quantity"] as! String
                    let manafacturer = data["manafacturer"] as! String
                    self.rawMaterialManafacturers.append(manafacturer)
                    self.rawMaterialQuantities.append(quantity)
                  //self.rawMaterialQuantities.append(data!["quantity"] as! String)
                  //self.rawMaterialManafacturers.append(data!["manafacturer"] as! String)
                }
            }
        })

编辑：既然，没有人能够提供帮助，也许我提供的不够。我的firebase实时数据库树看起来像这样

应用名称

-contracts

--- ContractTest

-rawMaterials

---可选（ “画图”）

-------- manafacturer：“可选（\”Paint Company A \“）”

--------数量：“可选（\”120 \“）”

---可选（ “铅”）

Answer 1

您错过了一个能够转换为String的步骤：

ref.child("rawMaterials").observeSingleEvent(of: .value, with: { (snapshot) in
    for child in snapshot.children {
        let nameSnapshotValue = child.value as! FIRDataSnapshot
        let name = nameSnapshotValue["name"] as! String //or whatever the dictionary key is...
        self.rawMaterialNames.append(name)
    }
})

如何将'FIRDataSnapshot'转换为NSString＆amp; NSDict

1 个答案: