iOS中滑动控制屏幕亮度和系统音量（附加AVAudioPlayer基本用法和Masonry简单使用）

 //获得当前屏幕亮度  light = [UIScreen mainScreen].brightness;  light = 0.5f;  //直接赋值或者使用set方法皆可  [UIScreen mainScreen].brightness = light;

MPMusicPlayerController *mpVC = [MPMusicPlayerController applicationMusicPlayer];//获得系统当前音量voice = _mpVC.volume;voice = 0.5f;//改变系统音量_mpVC.volume = voice;

- (void)leftSwipGes:(UIPanGestureRecognizer *)leftSwip{  //滑动方法获取到当前位置的y坐标  leftCurrentY = [leftSwip translationInView:leftView].y;  NSLog(@"left");  //当前坐标大于上一次移动的坐标，为向下滑动  if (leftCurrentY > leftLastY) {    if (light > 0) {      //向下滑动屏幕变暗，亮度下降      light = light - 0.01;    }    else{      //当亮度为0时固定为0，禁止为负值      light = 0;    }  }  else  {    if (light < 1) {      //向上滑动亮度增加      light = light + 0.01;    }    else{      //当亮度为1时固定为1，禁止大于1      light = 1;    }  }  //设置屏幕亮度  [UIScreen mainScreen].brightness = light;  //当前位置的上一次移动的位置y坐标  leftLastY = leftCurrentY;}//此处除参数外原理一样，不再额外注释- (void)rightSwipGes:(UIPanGestureRecognizer *)rightSwip{  NSLog(@"right");  rightCurrentY = [rightSwip translationInView:rightView].y;  if (rightCurrentY > rightLastY) {    if (voice > 0) {      voice = voice - 0.01;    }    else{      voice = 0;    }  }  else  {    if (voice < 1) {      voice = voice + 0.01;    }    else{      voice = 1;    }  }  //设置系统音量  _mpVC.volume = voice;  rightLastY = rightCurrentY;}

//从budle路径下读取音频文件,这个文件名是你的歌曲名字,mp3是你的音频格式  NSString *string = [[NSBundle mainBundle] pathForResource:@"夜空中最亮的星" ofType:@"mp3"];  NSString *playUrl = [string stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; //转码成UTF-8 否则可能会出现错误  //把音频文件转换成url格式  NSURL *url = [NSURL URLWithString:playUrl];  //初始化音频类 并且添加播放文件  _avAudioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:nil];  [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];  //设置初始音量大小  _avAudioPlayer.volume = voice;  //设置音乐播放次数 -1为一直循环  _avAudioPlayer.numberOfLoops = -1;  //预播放  [_avAudioPlayer prepareToPlay];  [_avAudioPlayer play];

 [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];