CS193P Cassini代码在模拟器上运行但在设备上崩溃了吗？ ＆＃34;来自调试器的消息：由于内存错误而终止＆＃34;

Question

我正在通过斯坦福大学的CS193P在线课程做ios dev。 第9讲通过简单的网址UIScrollView获取应用来处理UIImage /委托。该应用程序在模拟器中工作得非常好，但在尝试使用以下内容获取img后启动然后在实时设备（iPhone5）上崩溃：

  

来自调试器的消息：由于内存错误而终止

我回到我的代码，重新阅读委托，搜索SO（我发现了一个类似的线程，我确保我的项目方案没有启用僵尸）。我更新了我的设备，我的编译器/操作系统，并且有点担心可能会阻止它在设备上运行... 可以从https://web.stanford.edu/class/cs193p/cgi-bin/drupal/system/files/sample_code/Cassini.zip的斯坦福大学下载类示例，但此代码的行为方式相同！这最初是为ios 8.1编写的，而我们是在8.4，是否有任何已知问题？

imageview控制器的代码：

import UIKit

class ImageViewController: UIViewController, UIScrollViewDelegate
{
    // our Model
    // publicly settable
    // when it changes (but only if we are on screen)
    //   we'll fetch the image from the imageURL
    // if we're off screen when this happens (view.window == nil)
    //   viewWillAppear will get it for us later
    var imageURL: NSURL? {
        didSet {
            image = nil
            if view.window != nil {
                fetchImage()
            }
        }
    }

    // fetches the image at imageURL
    // does so off the main thread
    // then puts a closure back on the main queue
    //   to handle putting the image in the UI
    //   (since we aren't allowed to do UI anywhere but main queue)
    private func fetchImage()
    {
        if let url = imageURL {
            spinner?.startAnimating()
            let qos = Int(QOS_CLASS_USER_INITIATED.value)
            dispatch_async(dispatch_get_global_queue(qos, 0)) { () -> Void in
                let imageData = NSData(contentsOfURL: url) // this blocks the thread it is on
                dispatch_async(dispatch_get_main_queue()) {
                    // only do something with this image
                    // if the url we fetched is the current imageURL we want
                    // (that might have changed while we were off fetching this one)
                    if url == self.imageURL { // the variable "url" is capture from above
                        if imageData != nil {
                            // this might be a waste of time if our MVC is out of action now
                            // which it might be if someone hit the Back button
                            // or otherwise removed us from split view or navigation controller
                            // while we were off fetching the image
                            self.image = UIImage(data: imageData!)
                        } else {
                            self.image = nil
                        }
                    }
                }
            }
        }
    }

    @IBOutlet private weak var spinner: UIActivityIndicatorView!

    @IBOutlet private weak var scrollView: UIScrollView! {
        didSet {
            scrollView.contentSize = imageView.frame.size // critical to set this!
            scrollView.delegate = self                    // required for zooming
            scrollView.minimumZoomScale = 0.03            // required for zooming
            scrollView.maximumZoomScale = 1.0             // required for zooming
        }
    }

    // UIScrollViewDelegate method
    // required for zooming
    func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
        return imageView
    }

    private var imageView = UIImageView()

    // convenience computed property
    // lets us get involved every time we set an image in imageView
    // we can do things like resize the imageView,
    //   set the scroll view's contentSize,
    //   and stop the spinner
    private var image: UIImage? {
        get { return imageView.image }
        set {
            imageView.image = newValue
            imageView.sizeToFit()
            scrollView?.contentSize = imageView.frame.size
            spinner?.stopAnimating()
        }
    }

    // put our imageView into the view hierarchy
    // as a subview of the scrollView
    // (will install it into the content area of the scroll view)
    override func viewDidLoad() {
        super.viewDidLoad()
        scrollView.addSubview(imageView)
    }

    // for efficiency, we will only actually fetch the image
    // when we know we are going to be on screen
    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)
        if image == nil {
            fetchImage()
        }
    }
}