所以我正在发出网络请求。我将 JSON 解析为自定义对象。在这些对象中，有一些 url 应该可以带回图像。其中一个 URL 返回一条错误消息 (404)，因此那里什么都没有!如何在其位置设置默认图像并阻止我的应用程序崩溃？这是我的代码!谢谢
import UIKit
class HomepageCollectionViewController: UICollectionViewController {
var imageCache = NSCache()
var hingeImagesArray = [HingeImage]()
var arrayToHoldConvertedUrlToUIImages = [UIImage]()
var task: NSURLSessionDataTask?
override func viewDidLoad() {
super.viewDidLoad()
// Makes the network call for HingeImages
refreshItems()
}
override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
return 1
}
override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return hingeImagesArray.count
}
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("imageReuseCell", forIndexPath: indexPath) as! ImageCollectionViewCell
let image = hingeImagesArray[indexPath.row]
if let imageURL = image.imageUrl {
if let url = NSURL(string: imageURL) {
//settingImageTpChache
if let myImage = imageCache.objectForKey(image.imageUrl!) as? UIImage {
cell.collectionViewImage.image = myImage
}else {
// Request images asynchronously so the collection view does not slow down/lag
self.task = NSURLSession.sharedSession().dataTaskWithURL(url, completionHandler: { (data, response, error) -> Void in
// Check if there is data returned
guard let data = data else {
return
}
// Create an image object from our data and assign it to cell
if let hingeImage = UIImage(data: data){
//cachedImage
self.imageCache.setObject(hingeImage, forKey: image.imageUrl!)
dispatch_async(dispatch_get_main_queue(), { () -> Void in
cell.collectionViewImage.image = hingeImage
//append converted Images to array so we can send them over to next view - only proble in that the only images converted at the ones you scrool to which is retarted
self.arrayToHoldConvertedUrlToUIImages.append(hingeImage)
print(self.arrayToHoldConvertedUrlToUIImages)
})
}
})
task?.resume()
}
}
}
return cell
}
最佳答案
您可以检查错误是否不为零，然后设置默认图像。
self.task = NSURLSession.sharedSession().dataTaskWithURL(url, completionHandler: { (data, response, error) -> Void in
if error != nil {
cell.collectionViewImage.image = UIImage(named:"default_image")
return
}
...
关于ios - 当你发出网络请求并且它没有带来图像时如何设置默认图像？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/36686081/