ios - swift/iOS8 : set imageView for next View Controller before Segue

Question

根据一些参数，我试图在第二个 VC 上设置一个图像，但不知何故它总是返回 null？？

这就是我所做的:

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

        if segue.identifier == "showDetail"  {
            println("going forth!")
            println(self.myButton.selected)

            let controller = segue.destinationViewController as? DetailVC

            if myButton.selected == true {
                var newImage = UIImage(named:"Test1")
                var oldImage = controller?.imageView.image
                println(oldImage)

                oldImage = newImage
            } else {
                var newImage = UIImage(named:"Test2")
                var oldImage = controller?.imageView.image
                println(oldImage)

                oldImage = newImage
            }

        } else {
            println("roflcopter")
        }
    }

detail VC基本“一无所有”:

import UIKit

class DetailVC: UIViewController {


    @IBOutlet weak var imageView: UIImageView!

    var testString:String!

    @IBAction func goBacktoMain(segue: UIStoryboardSegue) {

        println("going back")

    }

    override func viewDidLoad() {
        super.viewDidLoad()

        println("view Did Load")
        println(testString)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

}

第二个 VC 通过 Storyboard 设置了默认图像，但是当我使用断点 @let Controller 停止时，它会告诉我 imageview 实际上是空的，这是否只在细节 vc 显示一次后才设置？

€dit:设置字符串并在第二个 VC 上打印出来效果非常好

Answer 1

你在哪里设置图像？在 prepareForSegue 中，UIImageView IBOutlet 将不会加载。您必须像下面这样在 DetailVC 类中声明一个图像变量，并在 viewDidLoad 中设置该图像。

class  DetailVC
{
    var image:UIImage? = nil
    @IBOutlet weak var imageView: UIImageView!

    override func viewDidLoad()
    {
        imageView.image = image
    }
}

在您的prepareSegue 函数中，设置

let controller = segue.destinationViewController as? DetailVC
controller?.image = //Your Image according to conditions.