在Swift 3.1中可选绑定的情况下如何使用

Question

I was using if let loop in previous stage of swift but in updated version I am unable to use the same loop. I tried using guard let but it isn't working either.

let imageArray = dataObject?["image"] as! NSArray
    if let image = imageArray[0]{
         let imageURL = "compute.amazonaws.com/" + "\(image)"
         print(imageURL)  
         if let url: URL = URL(string:"\(imageURL)")!{
        let task = URLSession.shared.dataTask(with: url, completionHandler: { (responseData, responseUrl, error) -> Void in
            if let data = responseData{
                DispatchQueue.main.async(execute: { () -> Void in
                    cell?.imageViewProduct.image = UIImage(data: data)
                })
            }
        })
        task.resume()
    }
}

Here my image ie imageArray[0] is optional value. It might not be supplied from backend in some cases so I want to use if let or similar.

Answer 1

I'm not sure, what is your problem, but I would rather make it this way:

guard let imageArray = dataObject?["image"] as? [String] else {return} //as I understand, names of images here
    guard let image = imageArray.firstObject else {return}

    let imageURL = "compute.amazonaws.com/\(image)"
    print(imageURL)

    if let url = URL(string:"\(imageURL)") {
        let task = URLSession.shared.dataTask(with: url, completionHandler: { (responseData, responseUrl, error) -> Void in
            if let data = responseData{
                DispatchQueue.main.async(execute: { () -> Void in
                    cell?.imageViewProduct.image = UIImage(data: data)
                })
            }
        })
        task.resume()
    }

Slightly edited my code. You don't need to separate that string, either

Answer 2

try this :

let imageArray = dataObject?["image"] as! NSArray
if let image = "\(imageArray[0])" as? String{
     let imageURL = "compute.amazonaws.com/" + "\(image)"
     print(imageURL)  
     if let url: URL = URL(string:"\(imageURL)")!{
    let task = URLSession.shared.dataTask(with: url, completionHandler: { (responseData, responseUrl, error) -> Void in
        if let data = responseData{
            DispatchQueue.main.async(execute: { () -> Void in
                cell?.imageViewProduct.image = UIImage(data: data)
            })
        }
    })
    task.resume()
}
}