手电筒的开和关解决

1、首先需要引入AVFoundation.framework框架
2、在 .h文件中添加属性

#import <AVFoundation/AVFoundation.h>
@interface LightViewController : UIViewController
{
    BOOL isLightOn;
    AVCaptureDevice *device;
}

@property BOOL isLightOn;
@end

3. 在 .m 文件中实现

#import "LightViewController.h"

@interface LightViewController ()

@end
@implementation LightViewController

@synthesize isLightOn;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        self.navigationItem.title = @"手电筒";
    }
    return self;
}

4:

- (void)viewDidLoad
{
    [super viewDidLoad];
    UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [btn setFrame:CGRectMake(80, 150, 100, 80)];
    [btn addTarget:self action:@selector(btnClicked) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
    
    //AVCaptureDevice代表抽象的硬件设备
     // 找到一个合适的AVCaptureDevice
    device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    if (![device hasTorch]) {//判断是否有闪光灯
        UIAlertView *alter = [[UIAlertView alloc]initWithTitle:@"提示" message:@"当前设备没有闪光灯，不能提供手电筒功能" delegate:nil cancelButtonTitle:@"Cancel" otherButtonTitles:nil, nil];
        [alter show];
    }
    
    isLightOn = NO;
    
}

-(void)btnClicked
{
    isLightOn = 1-isLightOn;
    if (isLightOn) {
        [self turnOnLed:YES];
    }else{
        [self turnOffLed:YES];
    }
}

//打开手电筒
-(void) turnOnLed:(bool)update
{
    [device lockForConfiguration:nil];
    [device setTorchMode:AVCaptureTorchModeOn];
    [device unlockForConfiguration];
}

//关闭手电筒
-(void) turnOffLed:(bool)update
{
    [device lockForConfiguration:nil];
    [device setTorchMode: AVCaptureTorchModeOff];
    [device unlockForConfiguration];
}