UIImageView

• 讓UIImageView可以被點選的方式

let tap = UITapGestureRecognizer(target: self, action: #selector(imageViewCanBeClicked))
imageView.addGestureRecognizer(tap)
imageView.isUserInteractionEnabled = true

• 計算圖片大小

let imgData: NSData = NSData(data: UIImageJPEGRepresentation((image), 1)!)
let imageSize: Int = imgData.length
print("\(book.bookDetails.name) size of image in KB: %f ", Double(imageSize) / 1024.0)