i've tried use optional binding in code still comes nil when execute , debug wondering if have used incorrect method?
here code shows me trying parse json
here's code use try , parse json:
import foundation protocol listingmodelprotocol: class { func itemsdownloaded(items: nsarray) } class listingmodel: nsobject, nsurlsessiondatadelegate { weak var delegate: listingmodelprotocol! var data : nsmutabledata = nsmutabledata() let urlpath: string = "http://booksmart.hol.es/service.php" // changed path service.php lives func downloaditems() { let url: nsurl = nsurl(string: urlpath)! var session: nsurlsession! let configuration = nsurlsessionconfiguration.defaultsessionconfiguration() session = nsurlsession(configuration: configuration, delegate: self, delegatequeue: nil) let task = session.datataskwithurl(url) task.resume() } func urlsession(session: nsurlsession, datatask: nsurlsessiondatatask, didreceivedata data: nsdata) { self.data.appenddata(data); } func urlsession(session: nsurlsession, task: nsurlsessiontask, didcompletewitherror error: nserror?) { if error != nil { print("failed download data") }else { print("data downloaded") self.parsejson() } } func parsejson() { var jsonresult: nsmutablearray = nsmutablearray() do{ jsonresult = try nsjsonserialization.jsonobjectwithdata(self.data, options:nsjsonreadingoptions.allowfragments) as! nsmutablearray } catch let error nserror { print(error) } var jsonelement: nsdictionary = nsdictionary() let properties: nsmutablearray = nsmutablearray() for(var = 0; < jsonresult.count; i+=1) { jsonelement = jsonresult[i] as! nsdictionary let property = propertymodel() //the following insures none of jsonelement values nil through optional binding if let propertytype = jsonelement["property type"] as? string, let price = jsonelement["price"] as? string, let distance = jsonelement["distance"] as? string { property.propertytype = propertytype property.price = price property.distance = distance } properties.addobject(property) } dispatch_async(dispatch_get_main_queue(), { () -> void in self.delegate.itemsdownloaded(properties) }) } } here's code use download data database:
import foundation class propertymodel: nsobject { //properties var propertytype: string? var price: string? var distance: string? //empty constructor override init() { } //construct @propertytype, @price , @distance parameters init(propertytype: string, price: string, distance: string) { self.propertytype = propertytype self.price = price self.distance = distance } //prints object's current state override var description: string { return "property type: \(propertytype), price: \(price), distance: \(distance)" } } and here's code use try , table cells in swift:
import uikit class first_resultsviewcontroller: uiviewcontroller, uitableviewdatasource, uitableviewdelegate, listingmodelprotocol { //properties var feeditems: nsarray = nsarray() var selectedproperties : propertymodel = propertymodel() @iboutlet weak var propertylisttableview: uitableview! override func viewdidload() { super.viewdidload() //set delegates , initialize homemodel self.propertylisttableview.delegate = self self.propertylisttableview.datasource = self let listingmodel = listingmodel() listingmodel.delegate = self listingmodel.downloaditems() // additional setup after loading view. } func itemsdownloaded(items: nsarray) { feeditems = items self.propertylisttableview.reloaddata() } func tableview(tableview: uitableview, numberofrowsinsection section: int) -> int { // return number of feed items return feeditems.count } func tableview(tableview: uitableview, cellforrowatindexpath indexpath: nsindexpath) -> uitableviewcell { // retrieve cell let cellidentifier: string = "basiccell" let mycell: uitableviewcell = tableview.dequeuereusablecellwithidentifier(cellidentifier)! // location shown let item: propertymodel = feeditems[indexpath.row] as! propertymodel // references labels of cell mycell.textlabel!.text = item.propertytype return mycell } /* // mark: - navigation // in storyboard-based application, want little preparation before navigation override func prepareforsegue(segue: uistoryboardsegue, sender: anyobject?) { // new view controller using segue.destinationviewcontroller. // pass selected object new view controller. } */ }
the following code post , comment, not correct.
//the following insures none of jsonelement values nil through optional binding if let propertytype = jsonelement["property type"] as? string, let price = jsonelement["price"] as? string, let distance = jsonelement["distance"] as? string the above not ensuring values not nil. if statement checking if of jsonelement not nil enter , set properties.
also, if of above properties not string in ur json response, not enter if statement. should checking type return. replace as? double type json response return.
if let propertytype = jsonelement["property type"] as? string, let price = jsonelement["price"] as? double, let distance = jsonelement["distance"] as? double { property.propertytype = propertytype property.price = "\(price)" property.distance = "\(distance)" } if want set empty string when nil, should using as string ?? "".
//the following ensure when element nil, change empty string , update our attributes let propertytype = jsonelement["property type"] as? string ?? "" let price = jsonelement["price"] as? string ?? "" let distance = jsonelement["distance"] as? string? ?? property.propertytype = propertytype property.price = price property.distance = distance you no longer need if statement anymore not nil.
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