1、导入相应的库文件AVFoundation

2、

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];  
    if (![device hasTorch]) {  
        NSLog(@"no torch");  
    }else{  
        [device lockForConfiguration:nil];  
        if (!on) {  
            [device setTorchMode: AVCaptureTorchModeOn];  
        }  
        else  
        {  
            [device setTorchMode: AVCaptureTorchModeOff];  
        }  
          
        [device unlockForConfiguration];  
    }