Question

在集合视图单元格中呈现单元格时会出现症状延迟，我已在此处录制https://youtu.be/2utKOpHMshs

我不太确定滞后是如何发生的，并且开始怀疑它与配方名称元素而不是UIImage有关，因为它在另一个线程上。

异步功能

func asyncLoadImage(data: NSData, imageView: UIImageView) {
    let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
    dispatch_async(dispatch_get_global_queue(priority, 0)) {
        var image: UIImage!
        NSLog("loading image")
        image = UIImage(data: data)
        dispatch_async(dispatch_get_main_queue()) {
            imageView.image = image
            NSLog("render image")
        }
    }
}

RecipeListViewController

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier(Storyboard.CellIdentifier, forIndexPath: indexPath) as!RecipeListCollectionViewCell
    let recipe = recipes[indexPath.item] as! Recipe
    cell.recipeName?.text = recipe.name?.uppercaseString
    cell.layer.shouldRasterize = true
    cell.layer.rasterizationScale = UIScreen.mainScreen().scale
    if (recipe.photo != nil) {
        asyncLoadImage(recipe.photo!, imageView: cell.recipeImageView)
    }        
    return cell
}

UICollectionViewCell：初始化

recipeImageView = UIImageView(frame: CGRect(x: 0, y: 0, width: frame.size.width, height: frame.size.height-100))
recipeImageView.contentMode = UIViewContentMode.ScaleAspectFill
recipeImageView.clipsToBounds = true
self.addSubview(recipeImageView)

recipeName = UILabel(frame: CGRect(x: 0, y: frame.size.height-100, width: frame.size.width, height: 50))
recipeName.backgroundColor = UIColor(red: 255, green: 255, blue: 255, alpha: 1)
recipeName.textColor = UIColor.blackColor()
recipeName.textAlignment = NSTextAlignment.Center
recipeName.font = UIFont.boldSystemFontOfSize(18.00)
self.addSubview(recipeName)

Answer 1

通过删除以下代码解决了该问题

> d1=as.dist(distm(df1[,c(1:2)])/10^5)
Error: cannot allocate vector of size 670.6 Gb
In addition: Warning messages:
1: In matrix(0, ncol = n, nrow = n) :
Reached total allocation of 16070Mb: see help(memory.size)
2: In matrix(0, ncol = n, nrow = n) :
Reached total allocation of 16070Mb: see help(memory.size)
3: In matrix(0, ncol = n, nrow = n) :
Reached total allocation of 16070Mb: see help(memory.size)
4: In matrix(0, ncol = n, nrow = n) :
Reached total allocation of 16070Mb: see help(memory.size)
> d2=dist(df1[,c(3:8)], method = "euclidean") 
Error: cannot allocate vector of size 335.3 Gb
In addition: Warning messages:
1: In dist(df1[, c(3:8)], method = "euclidean") :
 Reached total allocation of 16070Mb: see help(memory.size)
2: In dist(df1[, c(3:8)], method = "euclidean") :
Reached total allocation of 16070Mb: see help(memory.size)
3: In dist(df1[, c(3:8)], method = "euclidean") :
Reached total allocation of 16070Mb: see help(memory.size)
4: In dist(df1[, c(3:8)], method = "euclidean") :
Reached total allocation of 16070Mb: see help(memory.size)
> d3= hamming.distance(df1[,c(9:12)]%>%as.matrix(.))%>%as.dist(.)
Error: cannot allocate vector of size 670.6 Gb
In addition: Warning messages:
1: In matrix(0, nrow = nrow(x), ncol = nrow(x)) :
Reached total allocation of 16070Mb: see help(memory.size)
2: In matrix(0, nrow = nrow(x), ncol = nrow(x)) :
Reached total allocation of 16070Mb: see help(memory.size)
3: In matrix(0, nrow = nrow(x), ncol = nrow(x)) :
Reached total allocation of 16070Mb: see help(memory.size)
4: In matrix(0, nrow = nrow(x), ncol = nrow(x)) :
Reached total allocation of 16070Mb: see help(memory.size)

即使使用dispatch_async，UICollectionViewCell UIImage也会延迟

1 个答案: