Recently I have been developing a chat application and was having trouble asynchronously loading images with the chat.
Working with MessageKit - 2.0
I had tried this
import MessageKit
class Image: MediaItem {
var url: URL?
var image: UIImage?
var placeholderImage: UIImage
var size: CGSize
init(url: URL) {
self.url = url
self.size = CGSize(width: 240, height: 240)
self.placeholderImage = UIImage()
DispatchQueue.global().async {
if let data = try? Data(contentsOf: url) {
if let image = UIImage(data: data) {
DispatchQueue.main.async {
self.image = image
}
}
}
}
}
init(image: UIImage) {
self.image = image
self.size = CGSize(width: 240, height: 240)
self.placeholderImage = UIImage()
}
}
Then I initialize the Image MessageType with kind = .photo(Image(url: url))
This doesn't seem to work.
I have since learnt that MessageKit provides a delegate method in MessagesDisplayDelegate called
func configureMediaMessageImageView(_ imageView: UIImageView,
for message: MessageType,
at indexPath: IndexPath,
in messagesCollectionView: MessagesCollectionView)
We can asynchronously load images for given message with this delegate method.
I am using a UIImageView extension to help with this
import UIKit
extension UIImageView {
func load(url: URL) {
DispatchQueue.global().async { [weak self] in
if let data = try? Data(contentsOf: url) {
if let image = UIImage(data: data) {
DispatchQueue.main.async {
self?.image = image
}
}
}
}
}
}
So the solution is as follows
func configureMediaMessageImageView(_ imageView: UIImageView,
for message: MessageType,
at indexPath: IndexPath,
in messagesCollectionView: MessagesCollectionView) {
/*acquire url for the image in my case i had a
custom type Message which stored the image url */
guard
let msg = message as? Message,
let url = msg.downloadURL
else { return }
imageView.load(url: url)
}