使用pushViewController传递数据？

Question

使用此代码,我可以"segue"到我的视图控制器的同一个实例

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let vc = storyboard.instantiateViewController(withIdentifier: "DetailVC")
    self.navigationController?.pushViewController(vc, animated: true)


}

但是,如何传递数据？我只知道如何使用segue选项传递数据.当我用这个运行代码时,我得到nil错误,因为新的实例化视图控制器无法读取数据.

Answer 1

例如我在这里添加,有关详细说明,您可以从此处获取教程

class SecondViewController: UIViewController {

var myStringValue:String?

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
}

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)

    // We will simply print out the value here
    print("The value of myStringValue is: \(myStringValue!)")
}

并将字符串发送为

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let vc = storyboard.instantiateViewController(withIdentifier: "DetailVC") as! SecondViewController
      vc.myStringValue = "yourvalue"

    self.navigationController?.pushViewController(vc, animated: true)


}

Answer 2

首先.这不是一个segue.这只是将另一个视图推向堆栈.并且(如Ashley Mills所说)这与您当前所处的实例不同.这是一个视图控制器的新实例.

但您需要做的就是填充数据.你已经在这里安装了控制器......

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    // you need to cast this next line to the type of VC.
    let vc = storyboard.instantiateViewController(withIdentifier: "DetailVC") as! DetailVC // or whatever it is
    // vc is the controller. Just put the properties in it.
    vc.thePropertyYouWantToSet = theValue

    self.navigationController?.pushViewController(vc, animated: true)
}

Answer 3

你使用的不是转场。这只是将视图控制器的一个新实例（不是同一个）推送到导航堆栈上。

继续，在您的故事板中，您只需将链接从集合视图单元格拖到视图控制器，然后在prepareForSegue方法中分配数据......

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if let viewController = segue.destinationViewController as? DetailVC {
        viewController.someProperty = self.someProperty
    }
}