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iOS

Posted by mixforce
mixforce
9,747 Points

Does anyone know how to show an image from URL with Swift?

I am trying to show an external Image from an URL.

2 Answers

Daniel Sattler
Daniel Sattler
4,867 Points
Daniel Sattler
Daniel Sattler
4,867 Points

There are several ways to get this done.

Async:

dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {

var myImage =  UIImage(data: NSData(contentsOfURL: NSURL(string:"http://upload.wikimedia.org/wikipedia/en/4/43/Apple_Swift_Logo.png")))
})

or, as i prefer, a cached async version:

Create a new Class or a new iOS Swift File with this content:

class ImageLoader {

    var cache = NSCache()

    class var sharedLoader : ImageLoader {
        struct Static {
            static let instance : ImageLoader = ImageLoader()
        }
        return Static.instance
    }

    func imageForUrl(urlString: String, completionHandler:(image: UIImage?, url: String) -> ()) {
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), {()in
            var data: NSData? = self.cache.objectForKey(urlString) as? NSData

            if let goodData = data {
                let image = UIImage(data: goodData)
                dispatch_async(dispatch_get_main_queue(), {() in
                    completionHandler(image: image, url: urlString)
                })
                return
            }

            var downloadTask: NSURLSessionDataTask = NSURLSession.sharedSession().dataTaskWithURL(NSURL(string: urlString)!, completionHandler: {(data: NSData!, response: NSURLResponse!, error: NSError!) -> Void in
                if (error != nil) {
                    completionHandler(image: nil, url: urlString)
                    return
                }

                if data != nil {
                    let image = UIImage(data: data)
                    self.cache.setObject(data, forKey: urlString)
                    dispatch_async(dispatch_get_main_queue(), {() in
                        completionHandler(image: image, url: urlString)
                    })
                    return
                }

            })
            downloadTask.resume()
        })

    }
}

and in your actual viewController file use this:

ImageLoader.sharedLoader.imageForUrl("http://upload.wikimedia.org/wikipedia/en/4/43/Apple_Swift_Logo.png", completionHandler:{(image: UIImage?, url: String) in
            self.myImage.image = image!
        })

i hope this helps.

mixforce
mixforce
9,747 Points

That works! Thanks a lot!

nagendra rao
nagendra rao
Courses Plus Student 56 Points

The app freezes if the url doesn't return an image! "http://upload.wikimedia.org/wikipedia/en/4/43/Apple_Swift_Logo.png" no longer exists and the app breaks, how do I handle the 404 image links in this code?

nagendra rao
nagendra rao
Courses Plus Student 56 Points

Got it!

This is what is creating problem when the link is not found, below I have corrected the code,

ImageLoader.sharedLoader.imageForUrl("http://upload.wikimedia.org/wikipedia/en/4/43/Apple_Swift_Logo.png", completionHandler:{(image: UIImage?, url: String) in
   self.myImage.image = image
})

Notice that I have removed the ! after "image"

Daniel Sattler
Daniel Sattler
4,867 Points
Daniel Sattler
Daniel Sattler
4,867 Points

You are very welcome ;-)

mixforce
mixforce
9,747 Points

if possible, could you please help me out of this question as well?

https://teamtreehouse.com/forum/importing-a-json-that-contains-imageurl-text

Thanks Daniel.