ios - Swift:不知道如何调用我的委托(delegate)

Question

我是 Swift 的新手。我完全无法理解委托(delegate)。我有两个 View Controller ，我需要为另一个我想使用委托(delegate)的 Controller 设置 var。我在这里搜索了很多主题，但没有任何帮助。我的 View Controller B 有一个 var myFlag，我想从 View Controller A 设置它。这里是 View Controller B 代码

protocol flagDelegate {       
    func anyFlag(flag: Bool!)
}

class myBViewController: UIViewController {    
    var myFlag: Bool = false

    override func viewDidLoad() {
        super.viewDidLoad()
        println("myFlag: \(self.myFlag)")   
    }

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        println("myFlag: \(self.myFlag)")   
    }

    func anyFlag(flag: Bool!) {
        self.myFlag = flag
    }
} 

View Controller A 有一个按钮，它用代码加载 View Controller B:

@IBAction func addButton(sender: UIBarButtonItem) {
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let vc = storyboard.instantiateViewControllerWithIdentifier("myNC") as! UIViewController
        self.presentViewController(vc, animated: true, completion: nil)
    }

myNC 是一个包含 View Controller B 的导航 Controller 。我不知道如何设置委托(delegate)和调用它。请问你能帮帮我吗!提前致谢!

Answer 1

如果 View Controller A 在它即将显示的 View Controller ( View Controller B)上设置属性，则不需要使用委托(delegate)模式。委托(delegate)模式用于向后通信(从 B 到 A)。

所以你可以像这样在呈现 View Controller 之前设置一个属性:

@IBAction func addButton(sender: UIBarButtonItem) {
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let navigationVC = storyboard.instantiateViewControllerWithIdentifier("myNC") as! UINavigationController

    // get a reference to your VC
    let rootViewController = navigationVC.viewControllers[0] as MyBViewController

    // set the property
    rootViewController.myFlag = true // or false

    // or you could call the method you wrote
    rootViewController.anyFlag(true)

    // present the view controller
    self.presentViewController(navigationVC, animated: true, completion: nil)
}