從進入主隊列后，UI變得無響應

Question

我試圖從url延遲加載圖像並在僅在主隊列中接收到圖像時更新UI，UI得到更新，但視圖變得無響應，我正在使用GCD創建一個新線程來獲取網址中的數據

讓imageUrl：NSURL = NSURL（string：SiteAPIURL +（DEFAULTS.valueForKey（kInviterImageUrl）as！String））！

    let request: NSURLRequest = NSURLRequest(URL: imageUrl)
    SwiftLoader.show(title: "Loading", animated: true)


    let queue  : dispatch_queue_t = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)

  dispatch_async(queue) { () -> Void in
    let data : NSData = NSData(contentsOfURL: imageUrl)!
    let image = UIImage(data: data)!
    dispatch_async(dispatch_get_main_queue(), { () -> Void in
        self.userImage.image   = image
        self.userImageWide.image = image

    })



    }

}

Answer 1

“ DISPATCH_QUEUE_PRIORITY_HIGH：調度到隊列的項目以高優先級運行；該隊列計划在任何默認優先級或低優先級隊列之前執行。” 多數民眾贊成從文檔，所以使用其他優先級較低的東西，因為這可能會阻止默認隊列，例如QOS_CLASS_USER_INITIATED。 這就是你想要的

    if let url = imageUrl{
        let qos = Int(QOS_CLASS_USER_INITIATED.rawValue)
        dispatch_async(dispatch_get_global_queue(qos, 0), {
            let data = NSData(contentsOfURL: imageUrl)
            dispatch_async(dispatch_get_main_queue(), {
                if data != nil {
                    if let image = UIImage(data: data){
                        self.userImage.image   = image
                        self.image = UIImage(data: imageData!)
                        self.userImageWide.image = image
                    }
                }
            })
        })
    }