这是我第一次使用NSCache进行表视图。对于cellForRow
,我叫NSCache加载图像。该图像有时是错误的图像。我该怎么做才能解决此问题?如果缓存中不包含照片,则将照片替换为“ randomguy”。
func tableView(_ tableView: UITableView,cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "MyMessagesTableViewCell",for: indexPath) as! MyMessagesTableViewCell
if let cachedImage = cache.object(forKey: urlArray[indexPath.row] as NSString) as? UIImage {
cell.proPicImageView.image = cachedImage
cell.proPicImageView.layer.cornerRadius =
cell.proPicImageView.frame.size.height / 2
cell.proPicImageView.layer.masksToBounds = true
cell.proPicImageView.layer.borderWidth = 0
cell.usernameLabel.text = usernameArray[indexPath.row]
cell.messageLabel.text = messageArray[indexPath.row]
cell.messageLabel.textColor = colorArray[indexPath.row]
cell.messageLabel.font = fontArray[indexPath.row]
cell.timeLabel.text = timeArray[indexPath.row]
} else {
cell.proPicImageView.image = UIImage(named: "randomguy")
cell.proPicImageView.layer.cornerRadius =
cell.proPicImageView.frame.size.height / 2
cell.proPicImageView.layer.masksToBounds = true
cell.proPicImageView.layer.borderWidth = 0
cell.usernameLabel.text = usernameArray[indexPath.row]
cell.messageLabel.text = messageArray[indexPath.row]
cell.messageLabel.textColor = colorArray[indexPath.row]
cell.messageLabel.font = fontArray[indexPath.row]
cell.timeLabel.text = timeArray[indexPath.row]
}
return cell
}
在“查看是否加载”中: 让缓存= NSCache()
func photoQuery () {
for username in self.usernameArray {
let photoQuery = PFQuery(classname: "UserPhoto")
photoQuery.whereKey("username",equalTo: username)
photoQuery.findObjectsInBackground(block: { (objects:
[PFObject]?,error: Error?) in
if let objects = objects {
for object in objects {
if error == nil {
let userImageFile = object["photo"] as? PFFileObject
let urlString = userImageFile?.url as! String
if let url = URL(string: urlString) {
let data = try? Data(contentsof: url)
if let imageData = data {
self.messageImageArray.append(UIImage(data:imageData)!)
self.cache.setObject(UIImage(data:imageData)!,forKey: urlString as
NSString)
self.urlArray.append(urlString as NSString)
print(self.messageImageArray)
}
}
}
}
}
})
}
}