ios - fatal error : unexpectedly found nil while unwrapping an Optional value while using Swift

Question

我正在尝试在 Swift 中实现 UICollectionView。

我对 let array = objects.objectForKey("image_url") as [String] 行中的可选值有疑问

我不知道我的代码有什么问题。

ViewController.swift

import UIKit

var data: [String] = [] ;

class ViewController: UICollectionViewController{

override func viewDidLoad() {
    super.viewDidLoad()

    var collectionView: UICollectionView

    let json = "https://api.photozou.jp/rest/search_public.json?keyword=bike"//"http://dl.dropboxusercontent.com/u/7817937/nameko.json"
    let uri = NSURL(string: json)
    let uridata = NSData(contentsOfURL: uri)
    let objects = uridata.objectFromJSONData() as NSDictionary
    let array = objects.objectForKey("image_url") as [String]
    data += array

    //println(array)



}

override func numberOfSectionsInCollectionView(collectionView: UICollectionView?) -> Int {
    return 1
}

override func collectionView(collectionView: UICollectionView?, numberOfItemsInSection section: Int) -> Int {
    return data.count
}

override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    var cell = collectionView.dequeueReusableCellWithReuseIdentifier("cell", forIndexPath: indexPath) as CollectionViewCell
    let url = NSURL(string: data[indexPath.row])
    cell.image.setImageWithURL(url, placeholderImage: nil)

    return cell
}

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

有人解决这个错误吗？

Answer 1

你可以这样避免崩溃:

 if objects != nil  
{
   if objects.objectForKey("image_url") != nil
   {
      let array = objects.objectForKey("image_url") as [String]
       data += array
   }
}