syntax - Swift variable declaration trouble -

-

i'm following guide use syntax declare variable:

let fromview = presenting ? toview : transitioncontext.view(forkey: uitransitioncontextfromviewkey)

but don't understand syntax: specially question mark , colon (presenting boolean variable).

this allows declare variables based on boolean expressions. saves time don't have write out various if else statements. above expression in question declaring variable based on boolean presenting. if presenting true fromview gets set toview (on left side of colon). if presenting false, fromview gets set transitioncontext.view(forkey: uitransitioncontextfromviewkey) or right side of colon


Comments

Post a Comment

Popular posts from this blog

sequelize.js - Sequelize group by with association includes id -

-
so when requesting group sequelize follows: return models.workingcalendar .findall({ attributes: [ 'workingcalendar.periodid', 'workingcalendar.date', 'period.name' ], include: [ { model: models.period, attributes: [] } ], where: { getsudoid: currentgetsudo.id, unitplantid: unitplantid }, group: ['workingcalendar.periodid', 'workingcalendar.date', 'period.name'], }); sequelize run query: select [workingcalendar].[id], [workingcalendar].[periodid], [workingcalendar].[date], [period].[name] [workingcalendars] [workingcalendar] left outer join [periods] [period] on [wor...
Read more

java - Android raising EPERM (Operation not permitted) when attempting to send UDP packet after network connection -

-
when responding supplicant_state_changed_action broadcast , attempting send udp packet, exception: java.net.socketexception: sendto failed: eperm (operation not permitted) @ libcore.io.iobridge.maybethrowaftersendto(iobridge.java:542) @ libcore.io.iobridge.sendto(iobridge.java:511) @ java.net.plaindatagramsocketimpl.send(plaindatagramsocketimpl.java:184) @ java.net.datagramsocket.send(datagramsocket.java:305) @ com.mycompany.app.serviceclass.discover(serviceclass.java:355)at com.mycompany.app.serviceclass.access$600(serviceclass.java:39) @ com.mycompany.app.serviceclass$statemachine.run(serviceclass.java:242) @ java.lang.thread.run(thread.java:818) caused by: android.system.errnoexception: sendto failed: eperm (operation not permitted) @ libcore.io.posix.sendtobytes(native method) @ libcore.io.posix.sendto(posix.java:211) @ libcore.io.blockguardos.sendto(blockguardos.java:278) @ libcore.io.iobridge.sendto(iobridge.java:509) @ java.net.plaindat...
Read more

c++ - Migration from QScriptEngine to QJSEngine -

-
i'm migrating qscriptengine code on qjsengine. now, have: class pars { public: static qscriptvalue printmainlog(qscriptcontext* c, qscriptengine* e); }; qscriptvalue pars::printmainlog(qscriptcontext* c, qscriptengine* e) { //some actions return e->globalobject().property(""); } ... qscriptengine engine; ... engine.globalobject().setproperty("printlog",engine.newfunction(pars::printmainlog)); so, user can put printlog("what ever"); in application in , example, qlineedit , function pars::printmainlog evalute. is there way qjsengine? so, user put same printlog("what ever");? way find here , user should put logger.printlog("what ever"); logger class inherited qobject printlog slot.
Read more