CODEWITHSUNDEEP
iosswift
user6520075
user6520075

Reputation:

swift: tableview with images freezing

I have uitableview with 10 images in rows in my Xcode swift project. I use this code to show 10 images in rows in my uitableview:

 override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: String(format: "Cell0", indexPath.row), for: indexPath)


    var imageV = UIImageView()
    imageV = cell.viewWithTag(5) as! UIImageView

    imageV.image = UIImage(named:"image\(indexPath.row + 1).png")

But when I scroll my uitableview freezing very very very hard. Why is this happening? And How to fix it?

Upvotes: 1

Views: 1062

Answers (3)

Malik
Malik

Reputation: 3802

Create a custom cell

class MyCustomCell: UITableViewCell {
    @IBOutlet weak var imgView: UIImageView!
}

In your storyboard, set the class of the cell to MyCustomCell and give it an identifier say cell.

Then, update your cellForRow method as below

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! MyCustomCell

    let imageName = "image\(indexPath.row + 1).png"
    cell.imgView.image = UIImage(named: imageName)
    return cell
}

UPDATE

  • Create a new swift file called MyCustomCell.swift enter image description here
  • In storyboard, set your cell's class to MyCustomCell enter image description here
  • Add a UIImageView in your cell enter image description here
  • Connect the @IBOutlet enter image description here
  • Set your cell's identifier enter image description here
  • Update your cellForRow method enter image description here

Upvotes: 2

Aditya Srivastava
Aditya Srivastava

Reputation: 2650

let cell = tableView.dequeueReusableCell(withIdentifier: String(format: "Cell0", indexPath.row), for: indexPath)

to 

let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)  as CustomCell
cell.imageView.image = UIImage(named: "yourimagename")

Don't change your reusable identifier everytime. This is causing freezing in your case. Moreover create custom cell for adding UIImage.

Upvotes: 0

Alan
Alan

Reputation: 1142

The tableview is lagging and freezing on the scrolling because of how CellForRow works. Essentially, the OS does not save cells that are displayed. For example, rows 1-2-3 are displayed on the screen and have gone through cellForRow. Rows 4 is about to be displayed and row 1 will be removed off the screen. Row 4 will go through cellForRow for it's information to be displayed, and once row 1 is off the screen it will be removed from memory. So if you then scroll back to row 1, it will go through cellForRow and reload the image. So in this case your tableview is constantly loading images from the bundle as you scroll up and down.

Your solution might be to preload all your images and have them in an array so that the OS doesn't have to spend time loading the images repeatedly. Another way to go about might be to create a custom cell and simply have the cell handle loading it's own image by providing it the image name, rather than have the tableview manage the loading of every single's cell's image repeatedly. This would also clean up your cellForRow.

For example: make a new tableViewCell called imageCell which has an imageName property that could be an String. Once the cell is made, you simply pass it the string of it's image in cellForRow, and when the imageCell is created, have it load it's own image through this string in it's awakeFromNib.

Upvotes: 0

Related Questions