iOS adjusts the headset volume to the maximum method

-  (void) Setphonevolume{    mpvolumeview *volumeview = [[mpvolumeview  alloc] init];    UISlider* volumeViewSlider = nil;     for  (Uiview *view in [volumeview subviews]) {         if  ([view.class.description isequaltostring:@ "Mpvolumeslider"]) {             volumeViewSlider =  (uislider*) view;             break;         }    }        // retrieve  system volume    float systemVolume = volumeViewSlider.value;         // change system volume, the value  is between 0.0f and 1.0f    [volumeviewslider setvalue:1.0f animated:no];         // send ui control event to make the  change effect right now.    [volumeViewSlider  Sendactionsforcontrolevents:uicontroleventtouchupinside];}

iOS adjusts the headset volume to the maximum method