如何使用swift在表视图中实现延迟加载图像 [英] how to implement lazy loading of images in table view using swift

问题描述

我想使用swift在我的表视图中使用延迟加载概念。在我的表视图中，我显示了多个包含产品图像和产品名称的单元格。
请帮我解决问题。

I want to use lazy loading concept for my table view using swift. In my table view i am showing multiple cells which contain product images and product name . Please help me to get the solution.

推荐答案

旧解决方案：

由于您没有显示任何代码。

Since you doesn't show any code.

以下是您的示例。

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    // try to reuse cell
    let cell:CustomCell = tableView.dequeueReusableCellWithIdentifier("DealCell") as CustomCell

    // get the deal image
    let currentImage = deals[indexPath.row].imageID
    let unwrappedImage = currentImage
    var image = self.imageCache[unwrappedImage]
    let imageUrl = NSURL(string: "http://staging.api.cheapeat.com.au/deals/\(unwrappedImage)/photo")

    // reset reused cell image to placeholder
    cell.dealImage.image = UIImage(named: "placeholder")

    // async image
    if image == nil {

    let request: NSURLRequest = NSURLRequest(URL: imageUrl!)

    NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue(), completionHandler: {(response: NSURLResponse!,data: NSData!,error: NSError!) -> Void in
        if error == nil {

            image = UIImage(data: data)

            self.imageCache[unwrappedImage] = image
            dispatch_async(dispatch_get_main_queue(), {
                cell.dealImage.image = image

            })
        }
        else {

        }
    })
    }

    else{
        cell.dealImage.image = image
    }

  return cell

}

关注这个教程更多信息。希望这对你有所帮助。

Follow THIS tutorial for more Info. Hope this will help you.

新解决方案：

这是一个扩展名它是由我的朋友 Leo Dabus 创建的，它非常简单易用：

Here is extension for it which is created by my friend Leo Dabus which is really simple to use:

extension UIImageView {
    func downloadImageFrom(link link:String, contentMode: UIViewContentMode) {
        NSURLSession.sharedSession().dataTaskWithURL( NSURL(string:link)!, completionHandler: {
            (data, response, error) -> Void in
            dispatch_async(dispatch_get_main_queue()) {
                self.contentMode =  contentMode
                if let data = data { self.image = UIImage(data: data) }
            }
        }).resume()
    }
}

现在在 cellForRowAtIndexPath 方法中将图像分配给单元格：

Now in your cellForRowAtIndexPath method assign image to cell this way:

cell.cellImageView.image = UIImage(named: "placeholder")  //set placeholder image first.
cell.cellImageView.downloadImageFrom(link: imageLinkArray[indexPath.row], contentMode: UIViewContentMode.ScaleAspectFit)  //set your image from link array.

并且 Rob 建议在这里评论一些有用的库你可以使用：

And as Rob suggested into comment here is some useful libraries which you can use:

1. https://github.com/Alamofire/AlamofireImage


2. https://github.com/onevcat/Kingfisher


3. https://github.com/rs/SDWebImage


4. https://github.com/kean/DFImageManager

1. https://github.com/Alamofire/AlamofireImage
2. https://github.com/onevcat/Kingfisher
3. https://github.com/rs/SDWebImage
4. https://github.com/kean/DFImageManager

这篇关于如何使用swift在表视图中实现延迟加载图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！