Animation with song

I need to animate a few images with a song..So I fixed the timings for animation.I am using AVFoundation.Framework.But animation is not happening at perfect time..Its taking time for loading.I tried with AudioToolbox framework also.it is working for short duration s开发者_C百科ong,but not working for long duration song.How to fix this problem.Please help..

I would load all images before you start playing the audio and then hide/show/animate based upon position of playbackhead in audio player.