Async load image on swift / ios? -

here situation, ( please aware i'm starting on ios dev :) ).

i have list of feed data beign fetch firebase, each feed image , title in table view.

i'm looking way, if user come app without internet connection, still display data, whic have been display before that.

currently, i'm using display data:

import uikit import firebaseauth import firebasedatabase import firebasestorage import swiftkeychainwrapper import swiftyjson  var posts = [post]() var selectedindexpath: int = 10  class feedvc: uiviewcontroller, uitableviewdatasource, uiimagepickercontrollerdelegate, uinavigationcontrollerdelegate, uitableviewdelegate {  @iboutlet weak var feedtableview: uitableview!  private var readposts: observetask?  override func viewdidload() {     super.viewdidload()      feedtableview.datasource = self     feedtableview.delegate = self      readposts = post.observelist(from: post.parentreference.queryordered(bychild: "privacy").queryequal(tovalue: false))      {         observedposts in          posts = observedposts.reversed()         self.feedtableview.reloaddata()     } }  override var prefersstatusbarhidden: bool {     return true }  func numberofsections(in tableview: uitableview) -> int {     return 1 }  func tableview(_ tableview: uitableview, numberofrowsinsection section: int) -> int {     return posts.count }  func tableview(_ tableview: uitableview, heightforrowat indexpath: indexpath) -> cgfloat {     return uitableviewautomaticdimension }  func tableview(_ tableview: uitableview, estimatedheightforrowat indexpath: indexpath) -> cgfloat {     return uitableviewautomaticdimension }   func tableview(_ tableview: uitableview, cellforrowat indexpath: indexpath) -> uitableviewcell  {     let cell = self.feedtableview.dequeuereusablecell(withidentifier: "messagecell")! uitableviewcell    let imageview = cell.viewwithtag(1) as! uiimageview        let titlelabel = cell.viewwithtag(2) as! uilabel     let linklabel = cell.viewwithtag(3) as! uilabel      titlelabel.text = posts[indexpath.row].title     titlelabel.numberoflines = 0      linklabel.text = posts[indexpath.row].link     linklabel.numberoflines = 0        storage.getimage(with: posts[indexpath.row].imageurl){         postpic in         imageview.image = postpic     }      return cell  }   func tableview(_ tableview: uitableview, didselectrowat indexpath: indexpath) {     guard posts[indexpath.row].title != "coming soon" else {         return     }            selectedindexpath = indexpath.row           self.performsegue(withidentifier: "push", sender: self)             self.feedtableview.reloaddata()    }   } 

how possible ? i've been looking nsur function, start ?

thanks lot time !

use core data store images or

if don't want store these images in core data, since can impact performance if data set grows large. better write images files.

nsdata *pngdata = uiimagepngrepresentation(image); 

this pulls out png data of image you've captured. here, can write file:

nsarray *paths = nssearchpathfordirectoriesindomains(nsdocumentdirectory, nsuserdomainmask, yes);   nsstring *documentspath = [paths objectatindex:0]; //get docs directory  nsstring *filepath = [documentspath stringbyappendingpathcomponent:@"image.png"]; //add file name [pngdata writetofile:filepath atomically:yes]; //write file 

reading later works same way. build path did above, then:

nsdata *pngdata = [nsdata datawithcontentsoffile:filepath]; uiimage *image = [uiimage imagewithdata:pngdata]; 

what you'll want make method creates path strings you, since don't want code littered everywhere. might this:

- (nsstring *)documentspathforfilename:(nsstring *)name {     nsarray *paths = nssearchpathfordirectoriesindomains(nsdocumentdirectory,nsuserdomainmask, yes);       nsstring *documentspath = [paths objectatindex:0];      return [documentspath stringbyappendingpathcomponent:name];  } 

hope that's helpful.