Json feed blob image display in UIImage swift

There are a lot of questions here.

1. How did the image get inserted into the database?
2. Was it encoded in some way?
3. How was it retrieved?

You don't specify the answer here, so I am assuming it's raw image bytes. If that's not true, add some encoding or decoding as needed.

You can convert the string to NSData easily enough, then create a UIImage from it:

var imagedatastr:String = "" // assume this is the data you got from MySQL

if let imageData:NSData = imagedatastr.dataUsingEncoding(NSUTF8StringEncoding)
{
    let image = UIImage(data:imageData,scale:1.0)
}

Normally you have a string, and then you will show the image into a uiimageview, ok. Finally, you consider using a thread like this.

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0))
    {
        let data = NSData(contentsOfURL: NSURL(string: <yourUrlString>)
        var image: UIImage?
        if data != nil {
            artist.vImageData = data
            image = UIImage(data: data!)
        } else {
            image = UIImage(named: <defaultImageLikeNoAvailable>)
        }

        dispatch_async(dispatch_get_main_queue()) {
            imageView.image = image
        }
    }