Question

我正在尝试简化以下重复代码：

var cells = [Cell]()
var modules = [Module]()
var fields = [Field]()

root.child("cells").observeSingleEvent(of: .value) { (snapshot) in
    guard let dict = snapshot.value as? [String: Any],
        let cell = Cell(dict: dict) else { return }
    cells.append(cell)
}

root.child("modules").observeSingleEvent(of: .value) { (snapshot) in
    guard let dict = snapshot.value as? [String: Any],
        let module = Module(dict: dict) else { return }
    modules.append(module)
}

root.child("fields").observeSingleEvent(of: .value) { (snapshot) in
    guard let dict = snapshot.value as? [String: Any],
        let field = Field(dict: dict) else { return }
    fields.append(field)
}

Cell，Module，Field是自定义结构。我在想是否可以将他们的启动器init?(dict: [String: Any])放在一个数组中并将dict传递给它们中的每一个。

Answer 1

我认为你需要让你的结构采用一个协议：

protocol InitializableWithDictionary {
    init?(dict: [String : Any])
}

struct Cell: InitializableWithDictionary {

    //...

    init?(dict: [String : Any]){
        //...
    }
}

struct Module: InitializableWithDictionary {

   //...

    init?(dict: [String : Any]){
       //...
    }
}

struct Field: InitializableWithDictionary {

    //...

    init?(dict: [String : Any]){
        //...
    }
}

var cells: [InitializableWithDictionary] = [Cell]()
var modules: [InitializableWithDictionary] = [Module]()
var fields: [InitializableWithDictionary] = [Field]()

root.child("cells").observeSingleEvent(of: .value) { (snapshot) in

        guard let dict = snapshot.value as? [String: Any] else { return }

        let array: [InitializableWithDictionary.Type] = [Cell.self, Module.self, Field.self]

        array.forEach {

            if let element = $0.init(dict: dict) {

                switch element {

                case is Cell: cells.append(element)
                case is Module: modules.append(element)
                case is Field: fields.append(element)
                default: break
                }

            } else { return }
    }
}

Swift：是否可以迭代并调用函数数组？

1 个答案: