ios - Weird error while trying to play .mp3 sound effects in xcode? -

i trying code simplest 'press button hear sound' setup in xcode possible, , still managing cryptic errors. here code:

in .h file:

#import <avfoundation/avfoundation.h> 

in .m file:

- (ibaction)beepbutton:(uibutton *)sender {        nsurl* musicfile = [nsurl fileurlwithpath:[[nsbundle mainbundle]                                                    pathforresource:@"buttonbeep"                                                    oftype:@"mp3"]];         avaudioplayer *click = [[avaudioplayer alloc] initwithcontentsofurl:musicfile error:nil];         [click play];     //[click release]; } 

when try compile app, errors:

undefined symbols architecture armv7s:   "_objc_class_$_avaudioplayer", referenced from:       objc-class-ref in myfirstviewcontroller.o ld: symbol(s) not found architecture armv7s clang: error: linker command failed exit code 1 (use -v see invocation) 

am doing wrong? appreciated!

this called linker error. done after compiled ok.

the problem symbol _objc_class_$_avaudioplayer. ignore part through dollar sign leaving avaudioplayer.

since trying use avaudioplayer class , import <avfoundation/avfoundation.h> need realize must include avfoundation.framework in project.

if @ reference docs avaudioplayer, see docs state in avfoundation.framework. how know need add project.