GSSimpleImageView.swift

//
//  GSSimpleImageView.swift
//  GSSimpleImage
//
//  Created by 胡秋实 on 16/1/2016.
//  Copyright © 2016 CocoaPods. All rights reserved.
//

import UIKit

class GSSimpleImageView: UIImageView {
 
    var bgView: UIView!
    
    var animated: Bool = true
    
    //MARK: Life cycle
    override func drawRect(rect: CGRect) {
        super.drawRect(rect)
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        self.addTapGesture()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.addTapGesture()
        fatalError("init(coder:) has not been implemented")
    }
    
    //MARK: Private methods
    func addTapGesture() {
        let tap = UITapGestureRecognizer(target: self, action: "fullScreenMe")
        self.addGestureRecognizer(tap)
        self.userInteractionEnabled = true
    }
    //MARK: Actions of Gestures
    func exitFullScreen () {
        bgView.removeFromSuperview()
    }

    func fullScreenMe() {

        if let window = UIApplication.sharedApplication().delegate?.window {
            bgView = UIView(frame: UIScreen.mainScreen().bounds)
            bgView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: "exitFullScreen"))
            bgView.backgroundColor = UIColor.blackColor()
            let imageV = UIImageView(image: self.image)
            imageV.frame = bgView.frame
            imageV.contentMode = .ScaleAspectFit
            self.bgView.addSubview(imageV)
            window?.addSubview(bgView)
            
            if animated {
                var sx:CGFloat=0, sy:CGFloat=0
                if self.frame.size.width > self.frame.size.height {
                    sx = self.frame.size.width/imageV.frame.size.width
                    imageV.transform = CGAffineTransformMakeScale(sx, sx)
                }else{
                    sy = self.frame.size.height/imageV.frame.size.height
                    imageV.transform = CGAffineTransformMakeScale(sy, sy)
                }
                UIView.animateWithDuration(0.5, animations: { () -> Void in
                    imageV.transform = CGAffineTransformMakeScale(1, 1)
                })
            }
        }
    }

}

Neat work William!
How do you foresee considering orientation rotation scenarios? (i.e. a UITableViewCell containing a UIImageView as GSSimpleImageView thru Storyboard setup. Everything works fine, but when the device gets rotated, once in FullScreen mode, the component needs to rearrange).

UPDATE: Delegation with protocols looks like a right option.

Thanks a lot for the gist, works great,
Just a quick question, now the image pops up from the centre of the screen, can we make it coming from the frame of the image we tapped?

I have seen this in different apps, like Facebook, whatsapp etc?