I'm getting this error here:

image.load(url: product?.productImage!)

The definition of the image:

@IBOutlet var image: CellImageView!

And here is my CellImageView class:

import UIKit

class CellImageView: UIImageView {
    var task: URLSessionDataTask!
    var imageCache = NSCache<AnyObject, AnyObject>()

    func load(url: String) {
        let real_url = url.replacingOccurrences(of: *image_path_here*, with: *image_path_here*)
        let imageUrl = URL(string: real_url)
        image = nil

        if let task = task {
            task.cancel()
        }

        if let imageFromCache = imageCache.object(forKey: imageUrl?.absoluteString as AnyObject) as? UIImage {
            image = imageFromCache
        }

        task = URLSession.shared.dataTask(with: imageUrl!, completionHandler: { data, _, error in
            guard let data = data, let newImage = UIImage(data: data) else {
                print(error)
                return
            }
            self.imageCache.setObject(newImage, forKey: imageUrl?.absoluteString as AnyObject)
            DispatchQueue.main.async {
                self.image = newImage
            }
        })
        task.resume()
    }
}

I don't know why this giving me an error. Can someone help me about this?

CodePudding user response：

This error (usually) occurs when the compiler can't infer and subsequently verify the types in the code. In this case you are calling

func load(url: String)

so the method is expexcting a String as a parameter. However you are calling it with a parameter of product?.productImage! which is an optional (the ! doesn't override the ? for the class, so it remains optional.

You need to handle the optional properly

if let product = product, productImage = product.productImage {
   image.load(url: productImage}
} 

You would probably be better rethinking your caching too. You are using a local parameter to hold the cache, so every time you create a new instance of the class you create a new empty cache. Also an imageView isn't the best place for a cache anyway; consider extracting all the networking and caching to a dedicated controller.