我已经尝试异步加载图像一段时间了。 当我为此创建一个新类并构建并运行应用程序时，运行时日志中会出现错误
// log
Failed to set (borderWidth) user defined inspected property on ...
could not set nil as the value for the key borderWidth.
could not set nil as the value for the key cornerRadius.
使用扩展而不是类可以，图像加载异步，但是，这样我将无法确保在 ImageView 中加载正确的图像。
// cell for item at
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "subscribeCell", for: indexPath) as! subscribeViewCell
cell.userID = self.users[indexPath.row].userId
cell.profileName.text = self.users[indexPath.row].fullName
cell.profileImage.setupWithImageUrl(imageUrl: self.users[indexPath.row].ImagePath)
checkFollowers(indexPath : indexPath)
return cell
}
我一直在同一个 View Controller 中使用的类:
下载图像的类:
private var imageCache = [String:UIImage]()
class CustomImageView : UIImageView {
var lastImageUrl : String?
func setupWithImageUrl (imageUrl: String) {
self.contentMode = .scaleAspectFill
self.clipsToBounds = true
self.layer.cornerRadius = 14
self.layer.borderWidth = 0
lastImageUrl = imageUrl
if let cachedImage = imageCache[imageUrl] {
self.image = cachedImage
return
}
guard let url = URL(string: imageUrl) else {
return
}
URLSession.shared.dataTask(with: url) { (data, response, error) in
if let error = error {
print(error)
return
}
guard let data = data else {
return
}
guard let image = UIImage(data : data) else {
return
}
imageCache[url.absoluteString] = image
}
if (url.absoluteString != self.lastImageUrl) {
return
}
DispatchQueue.main.async {
self.image = self.image
}
}
}
最佳答案
为什么“这种方式”无法确保在 ImageView 中加载正确的图像。我读了你的代码，我认为你的代码适合 collectionViewController cellForItemAt
关于ios - 从 firebase 异步加载图像时出错，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51585985/