Swift中RSS提要数据源的表视图中的图像加载滞后

Question

我使用dispatch_async从rss提要下载图像以避免滞后，但当我快速滚动时，我可以看到图像在变化，这很烦人。我该如何避免这种情况？

这是我的代码：

let backgroundQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)
    dispatch_async(backgroundQueue, {
        let url = NSURL(string: fImage)
        let data = NSData(contentsOfURL: url!)
        dispatch_async(dispatch_get_main_queue(), { 
            if data != nil {
                self.thumbnailIMG.image = UIImage(data: data!)!
            } else {
                self.thumbnailIMG.image = UIImage(named: "logo_new2")!
            }
         })
     })

Answer 1

这样试试：

import UIKit
class ViewController: UIViewController {
@IBOutlet weak var thumbnailIMG: UIImageView!
override func viewDidLoad() {
    super.viewDidLoad()
    self.thumbnailIMG.image = UIImage(named: "logo_new2")
    if let checkedUrl = NSURL(string: "http://staging.api.cheapeat.com.au/restaurants/1/photo") {
        downloadImage(checkedUrl)
    }
}
func downloadImage(url:NSURL){
    getDataFromUrl(url) { data in
        dispatch_async(dispatch_get_main_queue()) {
            self.thumbnailIMG.image = UIImage(data: data!)
        }
    }
}
func getDataFromUrl(urL:NSURL, completion: ((data: NSData?) -> Void)) {
    NSURLSession.sharedSession().dataTaskWithURL(urL) { (data, response, error) in
        completion(data: NSData(data: data))
        }.resume()
    }
}

这对我来说并不落后。

也许这对你也有帮助。