ios - How to return a value from a function that is generated from a parse query within the function? -

-

problem: when call below function within viewcontroller tableview cellforrowatindexpath method, nil, need set generated object pfobject variable called rankobject declared globally in viewcontroller. i've tried lot of things, including completion handlers, , still stuck. how accomplish task?

func getormakerankrelations(sound: pfobject) {     var rankrelation = sound.relationforkey("userranks")     let currentuser = pfuser.currentuser()!     var relationquery = rankrelation.query()     relationquery?.wherekey("user", equalto: currentuser)     relationquery?.findobjectsinbackgroundwithblock { (theobject: [anyobject]?, error: nserror?) -> void in         if (theobject?.isempty == true) {             println("rank object empty")              //make ranking pfobject             var ranking = pfobject(classname: "ranking")             ranking["user"] = pfuser.currentuser()!             ranking["rank"] = 0              //upload ranking parse             ranking.saveinbackgroundwithblock { (saved: bool, error: nserror?) -> void in                 if saved {                     println("saved ranking")                      //add relation between sound , ranking                     rankrelation.addobject(ranking)                     sound.saveinbackgroundwithblock { (saved: bool, error: nserror?) -> void in                         if saved {                             println("saved relation")                             var theobject = (theobject![0] as? pfobject)!                             self.rankobject = theobject //////////note:  variable saves while in closure /////////////                         } else {                             println("relation not saved :(")                         }                     }                 } else {                     println(error)                 }             }         } else {             var theobject = (theobject![0] as? pfobject)!             self.rankobject = theobject  //////////note:  variable saves while in closure /////////////         }     } }

here how call function in tableview:

getormakerankrelation(sound)

not dealing specifics of asynch call, fact asynchronous, in objective-c (and swift) declare function take @ least 2 parameters: whatever needed parameterize remote request, , block run when request completes.

reading code, i'd advise breaking , create part own functions, remain sane, so...

- (void)getorcreaterankforsound:(pfobject *)sound completion:(void (^)(pfobject *, nserror *))completion {      [self getrankforsound:sound completion:^(pfobject *rank, nserror *error) {         if (!rank && !error) {  // there's no rank, , no error either, must create 1              [self createrankforsound:sound completion:^(pfobject *rank, nserror *error) {                 completion(rank, error);             }];          } else {             completion(rank, error);         }     }]; }  - (void)createrankforsound:(pfobject *)sound completion:(void (^)(pfobject *, nserror *))completion {      // build pfobject rank sound, save , tell our     // caller happened invoking completion block     // ...     [newlycreatedrank saveinbackgroundwithblock:^(bool success, nserror *error) {         return (success)? completion(newlycreatedrank, nil) : completion(nil, error);     }]; }

now cellforrowatindexpath can safely call method, because caches results.

// pseudo code in cellforrowatindexpath pfobject *sound = self.mydatasourcearray[indexpath.row];  // want change cell subview present rank object  // don't make network requests in method without caching result // assume have dictionary of rank objects indexed sound object id correspond pfobject *rank = self.ranksforsound[sound.objectid]; if (rank) {     // no need make network request, use rank, presumably update cell     cell.ranklabel.text = // function of rank } else {     // need make network request, put placeholder value in cell , call our function     cell.ranklabel.text = // placeholder value     [self getorcreaterankforsound:sound completion:^(pfobject *rank, nserror *error) {         // important, cell might have scrolled away time block runs         // don't alter cell directly, reload it.  cellforrowatindexpath         // called again, cache primed         if (!error) {             [tableview reloadrowsatindexpaths:@[indexpath]];         }     }]; } // configure other parts of cell return cell;

Comments

Post a Comment

Popular posts from this blog

c# - Better 64-bit byte array hash -

-
i need hash algorithm produces 64-bit hash code ( long ) fewer collisions string.gethashcode() , fast (no expensive calls cryptographic functions). here's implementation of fnv still shows 3% of collisions after testing 2 million random strings. need number way lower. void main() { const string chars = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz!#@$%^&*()_+}{\":?><,./;'[]0123456789\\"; const int n = 2000000; var random = new random(); var hashes = new hashset<long>(); int collisions = 0; for(int = 0; < n; i++) { var len = random.next(chars.length); var str = new char[len]; (int j = 0; j < len; j++) { str[j] = chars[random.next(chars.length)]; } var s = new string(str); if(!hashes.add(get64bithash( s ))) collisions++; } console.writeline("collision percentage after " + n + " random strings: " + ((doubl
Read more

webrtc - Which ICE candidate am I using and why? -

-
[questions in bold below] i have setup kurento media server 5.1.3 in datacenter behind firewall running os ubuntu 14.04. has 2 network cards: 222.222.222.222 (eth0 - private ip) 111.111.111.111 (eth1 - public ip) attached below sdp (setremotedescription) when browser connected kurento media server type: answer, sdp: v=0 o=- 5487318114793304426 0 in ip4 0.0.0.0 s=kurento media server c=in ip4 0.0.0.0 t=0 0 a=group:bundle audio video m=audio 59068 rtp/savpf 111 0 c=in ip4 111.111.111.111 a=rtpmap:111 opus/48000/2 a=rtpmap:0 pcmu/8000 a=sendrecv a=rtcp:59068 in ip4 111.111.111.111 a=rtcp-mux a=ssrc:669011897 cname:user39019747@host-6e83e4c2 a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time a=mid:audio b=as:20 a=ice-ufrag:ymdk a=ice-pwd:lylifk5ueqzpwm91ddj37e a=fingerprint:sha-256 ff:0f:81:8c:41:4e:b4:b6:c6:d8:36:f3:d6:5f:09:fd:5f:af:13:b3:9d:fc:12:66:ac:f3:56:d6:5b:0a:73:5d a=candidate:1 1 udp 2013266431 111.111.111.111 55239 typ host a=candidate:2 1 udp
Read more

php - Zend Framework / Skeleton-Application / Composer install issue -

-
i trying create zend framework application using skeleton in netbeans. when run composer install, following error message: "c:\php\php.exe" "c:\composer\composer.phar" "--ansi" "--no-interaction" "update" "--dev" using deprecated option "dev". dev packages installed default now. loading composer repositories package information updating dependencies (including require-dev) requirements not resolved installable set of packages. problem 1 - package requires php >=5.5 php version (5.4.42) not satisfy requirement. problem 2 - installation request zendframework/zendframework 2.5.1 -> satisfiable zendframework/zendframework[2.5.1]. - zendframework/zendframework 2.5.1 requires php >=5.5 -> php version (5.4.42) not satisfy requirement. done. apparently, zend framework only needs php 5.3+ contradicts above. need use php 5.4. my composer.json following: { "name": "
Read more