如何在viewDidLoad方法内部的UIViewController中初始化方法

Question

There is a method for creating data. This method needs to be called only once. So currently this is the structure:

var dataCreated : Bool? = false



override func viewDidLoad() {
    super.viewDidLoad()

    if dataCreated! == false {
        createData()
        self.dataCreated = true
    }
}

Is this the right way to ensure createData() method is called only once? Thank you.

Answer 1

Since you only want createData to be called once per instance of your view controller, then using viewDidLoad is a good place to call it. Further, since viewDidLoad is only called once per instance of the view controller, there is no need for the dataCreated property. You can remove that.

override func viewDidLoad() {
    super.viewDidLoad()

    createData()
}

Another option would be to call createData from the init method of the view controller. This depends on what createData needs to access. If the createData method needs access to views and outlets, then you must use viewDidLoad .

Answer 2

Your code will work as expected. You might prefer to compute whether data has been created by checking for its existence rather than tracking a separate Boolean variable. Although this will work too.