Question

我的图片有问题。我的表视图很慢。如何通过异步调用改进？在创建细胞的过程中，我有这个：

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    //IMPOSTA l'identifier della cella campione indexpath restituisce il numero della cella
    let cella = tableView.dequeueReusableCellWithIdentifier("record_cat", forIndexPath: indexPath) as! myTableViewCell

    if (musica.shared.id.count > 0) && (cella_select < musica.shared.id.count) {
        //label personalizzata cella con inserimento dell ARRAY IN BASE ALL'INDICE (indexPath.row indica il numero della cella quindi associa cella ad array)
        print(indexPath.row)

        cella.button_favorite.tag = indexPath.row
        cella.titolo.text = musica.shared.titles[indexPath.row]
        cella.artista.text = musica.shared.artists[indexPath.row]
        cella.logo_new.hidden = true

        let url_img = NSURL(string: "https://tuunes.co/app/upload/\(musica.shared.images[indexPath.row])")
        let data_img = NSData(contentsOfURL: url_img!)

        if (data_img != nil) {
            cella.immagine.image = UIImage(data: data_img!)
        } else {
            cella.immagine.image = UIImage(named: "cover-img-list")
        }

    } else {
        return cella
    }

    return cella
}

Answer 1

只需通过CocoaPods

安装SDWebImage即可

如何使用

在您的表所在的SDWebImage中导入ViewController：

import SDWebImage

然后在cellForRowAtIndexPath

中替换此代码

let data_img = NSData(contentsOfURL: url_img!)
if (data_img != nil){
      cella.immagine.image = UIImage(data: data_img!)
} else {
      cella.immagine.image = UIImage(named: "cover-img-list")
}

带

cella.immagine.sd_setImageWithURL(url_img!, placeholderImage: UIImage(named: "cover-img-list"))

Answer 2

//Set placeholder sync
cella.immagine.image = UIImage(named: "cover-img-list")

if let urlImg = NSURL(string: "https://tuunes.co/app/upload/\(musica.shared.images[indexPath.row])") {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
        //load data on the background thread
        if let dataImg =  NSData(contentsOfURL: urlImg) {
            dispatch_async(dispatch_get_main_queue()) {
                //Update UI on the main thread
                cella.immagine.image = UIImage(data: dataImg)
            }
        }
    }
}

如何异步加载图像以提高表视图性能？

2 个答案: