iOS 8 Free Memory after WebView (swift) - ios

Question

Currently i got a small problem with WebViews that dont release there memory usage in time, i m calling some webviews (the user can open them switch back to a map (via Tabbar) and open a new one),
Everytime a WebView is called it use up to 30MB RAM, so after 10 WebViews the App runs into a memory warning, so i m looking for a way (as i found in other Posts there is no way caus it handled automatic) to release the memory after switching back to the map from the webview.
This is how i call my WebView
import UIKit
class ViewController_webView: UIViewController {
/* ################################################## IBOutlets ################################################## */
#IBOutlet weak var webView: UIWebView!
#IBOutlet weak var TBB_shop: UITabBarItem!
#IBOutlet weak var activity: UIActivityIndicatorView!
/* ################################################## Home Button ################################################## */
#IBAction func BThome(sender: AnyObject) {
var shopurl = "http://google.com"
let webviewURL = NSURL(string: shopurl)
let request = NSURLRequest(URL: webviewURL)
webView.loadRequest(request)
}
/* ################################################## ViewDidLoad ################################################## */
override func viewDidLoad() {
super.viewDidLoad()
var TBB_shop_img = UIImage(named: "TabbarShopping.png") as UIImage
TBB_shop.selectedImage = TBB_shop_img
}
/* ################################################## MemoryWarning ################################################## */
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
println("Memory Warning")
}
/* ################################################## viewWillAppear ################################################## */
override func viewWillAppear(animated: Bool) {
var shopurl = "http://google.com"
let webviewURL = NSURL(string: shopurl)
let request = NSURLRequest(URL: webviewURL)
webView.loadRequest(request)
}
/* ################################################## Activity Indicator ################################################## */
func webViewDidStartLoad(_ : UIWebView){activity.startAnimating()}
func webViewDidFinishLoad(_ : UIWebView){activity.stopAnimating()}
}
Is there anyway to use the
override func viewDidDisappear(animated: Bool) {
<#code#>
}
to release the memory usage of a webview? Or anyway to reduce the usage of memory?

Answer 1

From your code I deduce that the webView is in a nib.
To reduce the memory footprint, you might want to try creating and removing the webView in viewWillAppear and viewWillDisappear, respectively.
This would mean that you might have to re-load the content if the user were to go back to it. Annoying from the user perspective.

Answer 2

Releasing memory can depend on how you are bringing up the view - here is a modal presentation of a view controller - this will not release memory of a previously loaded view controller:
let vc = self.storyboard!.instantiateViewControllerWithIdentifier("WebViewController") as WebViewController
let navigationController = UINavigationController(rootViewController: vc)!
self.presentViewController( navigationController, animated: true, completion: nil)
Below is a case where the rootViewController is replaced with the new controller - in this case the rootViewController value is changed - so the original view controller (if one was loaded before) reference count goes down to 0 and should be removed from memory, in theory:
let vc = self.storyboard!.instantiateViewControllerWithIdentifier("WebViewController") as WebViewController
let navigationController = UINavigationController(rootViewController: vc)!
let window = UIApplication.sharedApplication().windows[0] as UIWindow
window.rootViewController = navigationController
I tried the latter case in a code situation like what is described in the question. I saw an improvement in memory releasing, however I have to admit that the memory did not go back where I started from - don't know why. I hope somebody has a better solution.