objective c - Trouble hooking up AVAudioUnitEffect with AVAudioEngine -

i've been poking around avaudioengine , i'm having trouble integrating avaudiouniteffect classes. example, avaudiounitdelay...

@implementation viewcontroller { avaudioengine *engine; avaudioplayernode *player; } 

...

- (ibaction)playbuttonhit:(id)sender { if (!player){     nsurl *bandsurl = [[nsbundle mainbundle] urlforresource:@"bands managers" withextension:@"mp3"];     avaudiofile *file = [[avaudiofile alloc] initforreading:bandsurl error:nil];      engine = [[avaudioengine alloc] init];     player = [[avaudioplayernode alloc] init];     [engine attachnode:player];      avaudiounitdelay *delay = [[avaudiounitdelay alloc] init];     delay.wetdrymix = 50;      [engine connect:player to:delay format:file.processingformat];     [engine connect:delay to:[engine outputnode] format:file.processingformat];      [player schedulefile:file attime:nil completionhandler:nil];     [engine prepare];     [engine startandreturnerror:nil]; } [player play];   

}

when method called app crashes , error: "* terminating app due uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'required condition false: [_nodes containsobject: node1] && [_nodes containsobject: node2]'"

i'm modeling after of examples "avaudioengine in practice" session wwdc. know there's obvious i'm missing can't figure out....

it not problem of avaudiouniteffect! tried code

nserror *err = nil;  self.engine = [[avaudioengine alloc] init]; avaudioplayernode *player = [[avaudioplayernode alloc] init]; [self.engine attachnode:player];  nsurl *fileurl = [[nsbundle mainbundle] urlforresource:@"sound" withextension:@"m4a"]; avaudiofile *file = [[avaudiofile alloc] initforreading:fileurl error:&err];  avaudiomixernode *mainmixer = [self.engine mainmixernode]; [self.engine connect:player to:mainmixer format:file.processingformat];  [player schedulefile:file attime:nil completionhandler:nil];  [self.engine startandreturnerror:&err];  if (err != nil) {     nslog(@"an error occured"); }  [player play]; 

while self.engine defined by

@property (nonatomic, strong) avaudioengine *engine; 

i think bug in avaudioengine, because causes memory leak: starts playing first samples , crashes because of heavy memory usage (more 300 mb in case of 16 kb m4a file).

---

update 12/07/2014: apple fixed issue ios 8 seed 3 (build 12a4318c)!