Ios 将NSURLConnection更改为NSURLSession后，加载图像速度较慢

我在iOS 8中有一个加载图像的代码，速度非常快

if let url = NSURL(string: urlString) {
        let request = NSURLRequest(URL: url)
        NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) {
            (response: NSURLResponse?, data: NSData?, error: NSError?) -> Void in
            self.image = UIImage(data: data!)
        }
    }

然后iOS 9出来了，我很挣扎

let session = NSURLSession.sharedSession()
    let urlString = urlString
    let url = NSURL(string: urlString)
    let request = NSURLRequest(URL: url!)
    let dataTask = session.dataTaskWithRequest(request) { (data:NSData?, response:NSURLResponse?, error:NSError?) -> Void in
        self.image = UIImage(data: data!)
    }
    dataTask.resume()

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图像加载速度非常慢。

在

dataTaskWithRequest

关闭中，您必须在主线程上更新图像。这样做：

let dataTask = session.dataTaskWithRequest(request) { (data:NSData?, response:NSURLResponse?, error:NSError?) -> Void in
    dispatch_async(dispatch_get_main_queue()) {
        self.image = UIImage(data: data!)
    }
}

---

可能重复做得好！非常感谢你。图像加载速度更快！