ios - DidSet 在 init 函数 swift 3 中不起作用

Question

我已经看过了

Is it possible to allow didSet to be called during initialization in Swift?

对我来说这是行不通的..

我在下面创建类的项目中工作

protocol FileManagerHelper {

    var fileName:String {get}
    var fileCategory:FileCategory {get set}
    var isFileExitsAtPath:Bool {get}
    var filePath:String {get}
    var fileType:FileTypes {get set}

}

class FileManager:FileManagerHelper {
    // Other property 

    //STORED PROPERY INIT WHEN OBJECT WILL CREATED WITH FileCategory OBJECT 
     var fileCategory:FileCategory  {
    didSet {
        switch fileCategory {
        case .XYZ:
            print("Test")


        ... other cases 
         }
     }

    required init(fileCategory:FileCategory,fileType:FileTypes = .Image) {

        self.fileCategory = fileCategory
        self.path = self.folderPath + self.fileName

   }

 }

设置方法不是调用 fileCategory

注意:我不想给默认值，我想在运行时从 init 方法传递它

尝试

1) 延迟

use of self in method called $defer before all stored property are initialised

2) 创建将分配该值并从 init 调用它的自定义方法

 private func setCategory(with category:FileCategory) {
    self.fileCategory = category
}

Use of method call setCategory before stored property ...

我知道所有存储的属性都应该在创建实例之前初始化。直到那个实例不会被创建所以我不会调用方法(使用自己)可能是为什么上面的解决方案不起作用

有知道的请帮帮我

Answer 1

对我来说，使用 defer 可读性更好。

import Foundation

class A {
    var b: String {
        didSet {
            print("didSet called with value: \(b)")
        }
    }

    init(x: String) {
        self.b = x
        defer { self.b = x }
    }
}

let a = A(x: "It's Working!") // didSet called with value: It's Working!
print(a.b) // It's Working