Dynamic volume control AVPlayer

How can I change the volume of AVPlayer dynamically? I mean, I want to mute every time a button is pressed. this code seems to change it only at compile time. How to do this at runtime ???

AVURLAsset *asset = [AVURLAsset URLAssetWithURL:[self myAssetURL] options:nil];
NSArray *audioTracks = [asset tracksWithMediaType:AVMediaTypeAudio];
NSMutableArray *allAudioParams = [NSMutableArray array];
for (AVAssetTrack *track in audioTracks) {
    AVMutableAudioMixInputParameters *audioInputParams =[AVMutableAudioMixInputParameters audioMixInputParameters];
    [audioInputParams setVolume:0.0 atTime:kCMTimeZero];
    [audioInputParams setTrackID:[track trackID]];
    [allAudioParams addObject:audioInputParams];
}
AVMutableAudioMix *audioZeroMix = [AVMutableAudioMix audioMix];
[audioZeroMix setInputParameters:allAudioParams];
AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:asset];
[playerItem setAudioMix:audioZeroMix]; 
AVPlayer *player = [AVPlayer playerWithPlayerItem:playerItem];
self.mPlayer = player;
[mPlayer play];