ios - How to create alphabetical section headers with NSFetchedResultsController - Swift 3 -


i using nsfetchedresultscontroller populate tableview. tableview can quite long because shows list of people, , want sort alphabetically. know need use titleforheaderinsection, stuck on how first letter of each object in fetchedobjectscontroller.fetchedobjects , display section header sort it, how contacts app works.

this view controller looks like.

var fetchedresultscontroller: nsfetchedresultscontroller<client> = {     let fetchrequest: nsfetchrequest<client> = client.fetchrequest()     let sortdescriptors = [nssortdescriptor(key: "name", ascending: false)]     fetchrequest.sortdescriptors = sortdescriptors     return nsfetchedresultscontroller(fetchrequest: fetchrequest, managedobjectcontext: coredatastack.context, sectionnamekeypath: "name", cachename: nil) }()  override func numberofsections(in tableview: uitableview) -> int {     guard let sections = fetchedresultscontroller.sections else { return 0 }     return sections.count }   override func tableview(_ tableview: uitableview, numberofrowsinsection section: int) -> int {     guard let sections = fetchedresultscontroller.sections else { return 0 }     return sections[section].numberofobjects }   override func tableview(_ tableview: uitableview, cellforrowat indexpath: indexpath) -> uitableviewcell {     let cell = tableview.dequeuereusablecell(withidentifier: "clientcell", for: indexpath)     let client = fetchedresultscontroller.object(at: indexpath)     cell.textlabel?.text = client.name      return cell }  override func tableview(_ tableview: uitableview, commit editingstyle: uitableviewcelleditingstyle, forrowat indexpath: indexpath) {     if editingstyle == .delete {         let client = fetchedresultscontroller.object(at: indexpath)         clientcontroller.sharedcontroller.delete(client)     } }

this small example of how can headers texts, use class test have name, applying map using characters.prefix first characters of names , after casting string , sorting have need

var arrayofusers : [user] = [user(name:"test"),user(name:"pest"),user(name:"aest"),user(name:"nest"),user(name:"best")] let finalarray = arrayofusers.map({string.init($0.name.characters.prefix(1)) }).sorted(by: {$0 < $1}) debugprint(finalarray)

console log result

["a", "b", "n", "p", "t"]

hope helps you


Comments

Post a Comment

Popular posts from this blog

node.js - Node js - Trying to send POST request, but it is not loading javascript content -

i have been trying send post request website, , has not been loading full site. i guessing problem node js not loading javascript content, executing it. can see javascript in response, though never loads content javascript files producing in html. what mean is, doesn't execute javascript. how make node js code overcome this, , wait the full website load? have tried native code, , "request' module, both producing same errors. if helps, don't need native javascript. modules fine. some code have tried (request module): var options = { method: 'post', uri: 'https://url', formdata: { 'email': 'email', 'prize': '0', 'transactional': 'on' }, headers: { /* 'content-type': 'application/x-www-form-urlencoded' */ // set automatically } }; rp(options) .then(function (body) { console.log(body) }) .catch(function (err) { console.log(err) }); when fetch content...
Read more

javascript - Replicate keyboard event with html button -

i have tried few ways make happen. have javascript pinball game uses keyboard keys controls. converting application touch screen display. workaround, hoping overlay buttons when clicked simulate keyboard strokes. have done research , sounds should work. using jquery v3.2.1 here things have tried far... html element: <input type="button" class="coil"></input> $('.coil').trigger({type: 'keydown', which: 40, keycode: 40}); with this, not errors, nothing happens. var coilkey = $('body').keydown(function(e) { switch (e.keycode) { case 40: break;} }) $('.coil').click(coilkey); this 1 returns error in console... ((jquery.event.special[handleobj.origtype] || (intermediate value)).handle || handleobj.handler).apply not function below javascript game engine handles key listeners... addkeylistener: function (keyandlistener) { this.keylisteners.push(keyandlistener); }, // gi...
Read more

javascript - Web audio api 5.1 surround example not working in firefox -

i've been playing lott lately web audio api on both firefox , chrome. few days ago started experiment surround set. when trying surround audio in web audio api came notice example works fine in chrome v59 not in firefox v54. // create web audio api context var audioctx = new (window.audiocontext || window.webkitaudiocontext)(); audioctx.destination.channelinterpretation = 'discrete'; audioctx.destination.channelcountmode = 'explicit'; audioctx.destination.channelcount = 6; var oscillators = []; var merger = audioctx.createchannelmerger(6); console.log(audioctx.destination, merger); //merger.channelinterpretation = 'discrete'; //merger.channelcountmode = 'explicit'; //merger.channelcount = 6; var addoscilator = function(channel, frequency) { var oscillator = audioctx.createoscillator(); oscillator.frequency.value = frequency; // value in hertz oscillator.connect(merger,0,channel); oscillator.start(); oscillators.push(o...
Read more