Question

我正在尝试创建一个可以在浏览器之间滑动的应用程序（类似于Snapchat），我遇到了这个示例here

现在我尝试了这个，它完全符合我的要求。当我尝试在我的应用程序上实现相同时，我遇到了一些问题。

import UIKit

class ContainerViewController: UIViewController {
    // MARK: Properties
    @IBOutlet var scrollView: UIScrollView?;

    override func viewDidLoad() {
        super.viewDidLoad()

        let goal1 :GoalOneViewController =  GoalOneViewController(nibName: "GoalOneViewController", bundle: nil);
        let goal2 :GoalTwoViewController =  GoalTwoViewController(nibName: "GoalTwoViewController", bundle: nil);
        let goal3 :GoalThreeViewController =  GoalThreeViewController(nibName: "GoalThreeViewController", bundle: nil);


        // 2) Add in each view to the container view hierarchy
        //    Add them in opposite order since the view hieracrhy is a stack
        self.addChildViewController(goal3);
        // ERROR OCCURS ON LINE BELOW ----------------------------
        self.scrollView!.addSubview(goal3.view);
        goal3.didMoveToParentViewController(self);

        self.addChildViewController(goal2);
        self.scrollView!.addSubview(goal2.view);
        goal2.didMoveToParentViewController(self);

        self.addChildViewController(goal1);
        self.scrollView!.addSubview(goal1.view);
        goal1.didMoveToParentViewController(self);

        // 3) Set up the frames of the view controllers to align
        //    with eachother inside the container view
        var adminFrame :CGRect = goal1.view.frame;
        adminFrame.origin.x = adminFrame.width;
        goal2.view.frame = adminFrame;

        var BFrame :CGRect = goal2.view.frame;
        BFrame.origin.x = 2*BFrame.width;
        goal3.view.frame = BFrame;


        // 4) Finally set the size of the scroll view that contains the frames
        let scrollWidth: CGFloat  = 3 * self.view.frame.width
        let scrollHeight: CGFloat  = self.view.frame.size.height
        self.scrollView!.contentSize = CGSizeMake(scrollWidth, scrollHeight);


    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}

现在我在代码中标出了问题所在。我一直收到以下问题：

fatal error: unexpectedly found nil while unwrapping an Optional value

我不确定为什么。我已经尝试过调试，但我对swift / ios开发相对较新，所以我可能会忽略一些东西。

Answer 1

我认为

@IBOutlet var scrollView: UIScrollView?;

应该是：

@IBOutlet var scrollView: UIScrollView!

@IBOutlet var scrollView: UIScrollView?是否与您的viewController映射？

尝试在swift中添加子视图的问题

1 个答案: