ios - Duplicate symbol error with GoogleCast.framework -

i started porting android app ios, , hitting major roadblock can't figure out despite scouring many similar questions.

i attempting follow pattern implemented in castvideos sample googlecast api encapsulated in singleton class i've called castmanager. use singleton class, #import "castmanager.h" in appdelegate.m. in castmanager.h, #import <googlecast/googlecast.h> can use classes , protocols part of castmanager's public interface. however, because i'm importing castmanager.h in both castmanager.m , appdelegate.m, linker finding duplicate symbols googlecast framework.

this castmanager.h:

#import <googlecast/googlecast.h> #import <foundation/foundation.h>  @interface castmanager : nsobject  @property(nonatomic, strong) gckdevicescanner *devicescanner;  + (instancetype)sharedcastmanager;  @end 

and corresponding castmanager.m:

#import "castmanager.h"  @implementation castmanager  + (instancetype)sharedcastmanager {     nslog(@"sharedcastmanager");     static castmanager *singleton = nil;     static dispatch_once_t oncetoken;     dispatch_once(&oncetoken, ^{         singleton = [[self alloc] init];     });     return singleton; }  - (instancetype)init {     nslog(@"init()");     if (self = [super init]) {         self.devicescanner = [[gckdevicescanner alloc] init];     }     return self; }  @end 

and main part of appdelegate.m:

#import "appdelegate.h" #import "castmanager.h"  @implementation appdelegate  - (bool)application:(uiapplication *)application didfinishlaunchingwithoptions:(nsdictionary *)launchoptions {     castmanager *castmanager = [castmanager sharedcastmanager];     return yes; } 

however, results in following error linker when attempting build project:

duplicate symbol _kgckdevicecapabilityvideoout in:     /users/nate/library/developer/xcode/deriveddata/mycastapp-ezrgxdnlvywpanerezulnarzknno/build/intermediates/mycastapp.build/debug-iphonesimulator/mycastapp.build/objects-normal/x86_64/appdelegate.o     /users/nate/library/developer/xcode/deriveddata/mycastapp-ezrgxdnlvywpanerezulnarzknno/build/intermediates/mycastapp.build/debug-iphonesimulator/mycastapp.build/objects-normal/x86_64/castmanager.o ... many similar errors ommitted brevity ... duplicate symbol _kgckdevicecapabilityaudioin in:     /users/nate/library/developer/xcode/deriveddata/mycastapp-ezrgxdnlvywpanerezulnarzknno/build/intermediates/mycastapp.build/debug-iphonesimulator/mycastapp.build/objects-normal/x86_64/appdelegate.o     /users/nate/projects/mycastapp/googlecast.framework/googlecast(gckdevice.o) ld: 8 duplicate symbols architecture x86_64 clang: error: linker command failed exit code 1 (use -v see invocation) 

as far can tell, copies pattern defined in castvideos sample, sample compiles fine, , mine doesn't, , i've scoured through both projects trying find different, don't see it. further, don't see wrong doing this, , expect work fine. can't think of other way it, really.

here relevant files castvideos sample comparison:

• chromecastdevicecontroller.h
• chromecastdevicecontroller.m
• appdelegate.m

other questions point solutions don't apply or don't fix it:

• i'm not importing .m file on accident.
• i don't have duplicate references files in project.
• the "compile sources" section of "build phases" project setting doesn't include duplicates.
• i've added '-objc' linker flag described googlecast api docs, though has same error or without it.
• i've tried deleting delegate data , doing clean before building.
• this xcode 6.3.1 running on os x yosemite 10.10.3 , googlecastsdk-2.6.0 package the sdk documentation page

i have checked in sample project problem @ https://github.com/nshafer/mycastapp

any appreciated!

edit: duplicate related, it's same symbols, answers there didn't help, i'm not using object-c++, rather objective-c. don't have .mm file, .m file.

for me helped switch "no common blocks" compiler setting no:

it pretty seems make sense, setting explained here: what gcc_no_common_blocks used for?