ios - Swift closure in array becomes nil in Objective-c -


i created objective-c method invoke method via nsinvocation:

typedef void (^scriptingemptyblock)(); typedef void (^scriptingerrorblock)(nserror *error); - (void)scripting_execute:(nsstring *)operation withparams:(nullable nsarray *)args {      sel selector = [self scripting_selectorforoperation:operation];     class class = [self class];     nsmethodsignature *signature = [class instancemethodsignatureforselector:selector];     nsinvocation *invocation = [nsinvocation invocationwithmethodsignature:signature];      [invocation setselector:selector];     [invocation settarget:self];     (int idx = 0; idx < args.count; idx ++) {         id arg = args[idx];         [invocation setargument:&arg atindex:idx + 2];      }      scriptingemptyblock success = args[1];      // breakpoint added on next line test nil     success(); // nil , crash!     // (lldb) po args.count     // 3      // (lldb) po success     // printing description of success:     // (scriptingemptyblock) success = 0x0000000000000000      // (lldb) po args[1]     // (function)      //[invocation getargument:&success atindex:2]; // tried , got nil     [invocation invoke];  }

the method takes "operation" translated selector overriding scripting_selectorforoperation: in subclasses , performs invocation.

all of works, except when invoked method has block arguments nil, added test nil describe comments, when attempting read closure array nil.

called like:

let successclosure: scriptingemptyblock = {                     print("renamed product")                 } let errorclosure: scriptingerrorblock = { error in                     print("failed rename product: \(error)")                 } let params:[any] = [ "testname", successclosure, errorclosure] object.scripting_execute (scriptoperation.updateproductname.rawvalue, withparams: params)

why closure becoming nil?

success not nil (in fact, nsarray cannot contain nils). if print nslog(@"%@", success);, (function), not (null). , if print class nslog(@"%@", [success class]);, _swiftvalue. basically, swift value bridged objective-c.

the problem object success points not objective-c block. swift closure, , swift closures not same objective-c blocks. trying use invoke if objective-c block causes undefined behavior. po in debugger prints wrong because printing assuming type scriptingemptyblock (a block type). if po (id) success, print (function).

as how can explicitly put objective-c block array swift, way figured out like:

let params:[any] = [ "testname",                      successclosure (@convention(block) () -> void)!,                      errorclosure (@convention(block) (nserror) -> void)!] object.scripting_execute (scriptoperation.updateproductname.rawvalue,                           withparams: params)

i not sure why it's necessary put function type inside !, doesn't seem work otherwise. maybe else can find better way.


Comments

Post a Comment

Popular posts from this blog

PHP and MySQL WP -

i trying accomplish 2 things here code. writing php directly wp page using insert php plugin. 1) query mysql database , return results 1 column 4 columns. 2) make each result own hyperlink directs user new wp page runs new query on page. i able query show results , turn results dynamic hyperlink, cannot formatting down. right returns result 1 column. here have: [insert_php] $servername = "localhost"; $username = "login"; //edited privacy $password = "password"; //edited privacy $database = "database"; //edited privacy // create connection $conn = new mysqli($servername, $username, $password, $database); // check connection if ($conn->connect_error) { die("connection failed: " . $conn->connect_error); } echo "connected successfully"; //get results database $result = mysqli_query($conn,"select mine mines order mine"); $all_property = array(); //declare array saving property //showing proper...
Read more

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m...
Read more

nginx - phpPgAdmin - log in works but I have to login again after clicking on any links -

i have setup postgres 9.6 , phppgadmin on centos 7 server nginx, i can log in phppgadmin, postgresql server on right of page remains crossed out , link try browse (databases, roles etc) requires log in again. i'm thinking seems sessions problem, unsure how resolve it. any pointers on how fix or should looking @ in order track down problem? solved. turns out owner of /var/lib/php/session apache - needed nginx. sorted changing ownership nginx below: chown -r nginx:nginx /var/lib/php/session/
Read more