ios - Multiple AVAudioPlayers - No Sound -

i'm new xcode , objc , i'm having trouble playing multiple audio files through multiple avaudioplayers.

in theory app simple, takes cars rpm , load values , plays sound based on values.

so, have 13 sound samples range of rpm values. code figures out volume , rate should played @ replicate correct engine sounds in app - note playing @ same time, it's volume , rate controls how sound.

so, figure out volumes , rates (this snippet) :

if ((rpm > 4989) && (rpm < 5339)) {      av1pitch  = 0.0f;     av2pitch  = 0.0f;     av3pitch  = 0.0f;     av4pitch  = 0.0f;     av5pitch  = 0.0f;     av6pitch  = 0.0f;     av7pitch  = 0.0f;     av8pitch  = 0.0f;     av9pitch = rpm / 4989.0f;     av10pitch = rpm / 5338.0f;     av11pitch  = 0.0f;     av12pitch  = 0.0f;     av13pitch  = 0.0f;      av1volume  = 0.0f;     av2volume  = 0.0f;     av3volume  = 0.0f;     av4volume  = 0.0f;     av5volume  = 0.0f;     av6volume  = 0.0f;     av7volume  = 0.0f;     av8volume  = 0.0f;     av9volume = av9pitch - 1.0f;     av10volume = 1.0f - av9volume;     av11volume  = 0.0f;     av12volume  = 0.0f;     av13volume  = 0.0f; } 

then go through 13 avaudioplayers , set players volume , rate :

if (audioplayer2000.isplaying) {     //already playing, ready volume / pitch adjustments      audioplayer2000.volume = av2volume;     audioplayer2000.rate = av2pitch;    } else{     //nothing playing - play file     nsurl *url = [nsurl fileurlwithpath:[nsstring stringwithformat:@"%@/1052.wav", [[nsbundle mainbundle] resourcepath]]];     nserror *error;     //nsdata *songfile2 = [[nsdata alloc] initwithcontentsofurl:url options:nsdatareadingmappedifsafe error:&error];     audioplayer2000 = [[avaudioplayer alloc] initwithcontentsofurl:url error:&error];     //audioplayer2000 = [[avaudioplayer alloc] initwithdata:songfile2 error:&error];     audioplayer2000.numberofloops = -1;     audioplayer2000.enablerate = yes;     audioplayer2000.rate = av2pitch;     audioplayer2000.volume = av2volume;      if (audioplayer2000 == nil) {         nslog([error description]);     }     else{         [audioplayer2000 play];     }    } 

this works ok whilst playing 1 file, change rpm value should playing file, of sounds stop no matter rpm value is.

the way i've found stop call setcurrenttime on players - results in 'jittery' playback.

i thought might arc playing up, created properties players.

am missing fundamental here? or not taking right approach?