Add subview on tableView cells causes a sad patchwork - ios

Question

I want to give a chat aspect to a table view of messages in my iPhone app.
In order to perform a quality render I add two subviews: the text and the "container" which is just a view with background color.
Even if it works the first time, when I scroll, it becomes really messy because it keeps adding lots of subviews.
Here you can see it when clean
And then when it has become messy
Here is the function to handle the transform, it's called when scrolling.
func configChatCell(cell: UITableViewCell, text: String, color:UIColor)
{
cell.textLabel?.numberOfLines = 0
cell.textLabel?.lineBreakMode = NSLineBreakMode.ByWordWrapping
cell.textLabel?.textColor = UIColor.whiteColor()
let fixedWidth = cell.bounds.width - 150
let textView: UITextView = UITextView(frame: CGRect(x: 0, y: 0, width: 10, height: CGFloat.max))
textView.text = text
let newSize = textView.sizeThatFits(CGSize(width: fixedWidth, height: CGFloat.max))
var newFrame = textView.frame
newFrame.size = CGSize(width: min(newSize.width, fixedWidth), height: newSize.height)
textView.sizeThatFits(newFrame.size)
textView.frame = newFrame
textView.backgroundColor = UIColor.clearColor()
self.rowHeight = textView.frame.height+20
let view = UIView()
view.backgroundColor = color
print(textView.frame.height+10)
view.frame = CGRect(x: 0, y: 5, width: textView.frame.width+50, height: textView.frame.height+10)
view.layer.cornerRadius = 5
cell.backgroundColor = UIColor.clearColor()
cell.contentView.addSubview(view)
cell.contentView.addSubview(textView)
cell.contentView.sendSubviewToBack(view)
}
If I remove the subviews each time I scroll, nothing appears on screen.
Can somebody help me to find a solution? Or is there any other way to do this?
Thanks in advance!

Answer 1

I quickly wrote up something for this.
It starts with the ChatCell
class ChatCell: UITableViewCell {
var messageLabel: UILabel? {
didSet {
messageLabel?.text = message
}
}
var message: String? {
didSet {
messageLabel?.text = message
}
}
class func messageCell(withText text: String, leading: Bool = true) -> ChatCell {
let cell = ChatCell()
cell.message = text
// Make the container
let container = UIView()
container.translatesAutoresizingMaskIntoConstraints = false
cell.contentView.addSubview(container)
container.topAnchor.constraintEqualToAnchor(cell.contentView.topAnchor, constant: 8).active = true
container.bottomAnchor.constraintEqualToAnchor(cell.contentView.bottomAnchor, constant: -8).active = true
if leading {
container.leadingAnchor.constraintEqualToAnchor(cell.contentView.leadingAnchor, constant: leading ? 8 : 8*8).active = true
container.trailingAnchor.constraintLessThanOrEqualToAnchor(cell.contentView.trailingAnchor, constant: leading ? -8*8 : -8).active = true
} else {
container.leadingAnchor.constraintGreaterThanOrEqualToAnchor(cell.contentView.leadingAnchor, constant: leading ? 8 : 8*8).active = true
container.trailingAnchor.constraintEqualToAnchor(cell.contentView.trailingAnchor, constant: leading ? -8*8 : -8).active = true
}
// Make the messageLabel.
let messageLabel = UILabel()
messageLabel.numberOfLines = 0
messageLabel.textColor = UIColor.whiteColor()
messageLabel.translatesAutoresizingMaskIntoConstraints = false
container.addSubview(messageLabel)
// Add constraints.
messageLabel.topAnchor.constraintEqualToAnchor(container.topAnchor, constant: 8).active = true
messageLabel.bottomAnchor.constraintEqualToAnchor(container.bottomAnchor, constant: -8).active = true
messageLabel.leadingAnchor.constraintEqualToAnchor(container.leadingAnchor, constant: 8).active = true
messageLabel.trailingAnchor.constraintEqualToAnchor(container.trailingAnchor, constant: -8).active = true
cell.messageLabel = messageLabel
container.backgroundColor = UIColor(red:0.19, green:0.70, blue:1.00, alpha:1.00)
container.layer.cornerRadius = 12.0
return cell
}
}
The cell also includes support for leading and trailing messages, for back and forth conversation. Perhaps make an array of tuples like this:
let messages: [(message: String, leading: Bool)] = [("Hello", true), ("My name is John Doe and this works quite well", false), ("I would agree", true)]
Then in your tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell you could do this:
let cell = ChatCell.messageCell(withText: messages[indexPath.row].message, leading: messages[indexPath.row].leading)
return cell
Let me know if this works for you. I tested it in a Playground and it works as expected

Answer 2

Assuming that your configureChatCell is called from tableView:cellForRowAtIndexPath:, then #Paulw11 is right; cells are reused, so you should only make changes that are unique to that row in the table. In your example, the only calls that you should be making in your method are textView.text = text and the ones to resize the textView to fit. Everything else should go in a dynamic cell prototype in the storyboard or, if you want to do everything in code (which I have a bad feeling you do), then put the rest of the configuration in a UITableViewCell subclass, then register that subclass with your table view.

Answer 3

I write something like this. It's simple but can elucidate solution
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("reuseid", forIndexPath: indexPath)
// Configure the cell...
let contentView = cell.contentView
let subviews = contentView.subviews
for view in subviews {
if 100 == view.tag {
let label = view as! UILabel
label.text = self.datas[indexPath.row]
} else if 200 == view.tag {
view.layer.cornerRadius = 10.0
}
}
return cell
}
the key point is config every thing in tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
the view in code with tag 200 is a background view has same frame with label, I use layout constraint in storyboard to make sure its size and position.