实现类似qq扫一扫功能

最近公司项目需要实现一个类似qq扫一扫功能，该功能主要分为三个部分：扫一扫、扫描相册中二维码图片、开灯（我的二维码不是主要功能）

1.扫一扫

iOS7以后，AVFoundation.framework框架支持扫一扫功能，详细代码，可以参考http://www.jianshu.com/p/6b7d54b3f88b

但该博客中的代码只能简单的实现扫一扫功能，周围的背景并不是半透明的。



通过以下代码可以实现中间透明，旁边半透明的效果

-(void)setupBgView{
self.view.backgroundColor = [UIColor blackColor];
//绘制扫一扫背景，中间透明，旁边半透明
UIGraphicsBeginImageContext(self.view.frame.size);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(ctx, 0,0,0,0.5);
CGRect drawRect =CGRectMake(0, 0, Screen_Width, Screen_height);

//draw the transparent layer
CGContextFillRect(ctx, drawRect);

//clear the center rect  of the layer
drawRect = self.scanBg.frame;
CGContextClearRect(ctx, drawRect);

UIImage* returnimage = UIGraphicsGetImageFromCurrentImageContext();
UIImageView * img = [[UIImageView alloc] initWithImage:returnimage];
[self.view addSubview:img];
UIGraphicsEndImageContext();
}

但以上代码仍然存在一点小问题：这张背景图片是直接盖在最上层，导致扫一扫界面上的图片和文字效果不好（左图）。



只需将背景图片移到视图的最上层即可（右图）：

[self.view addSubview:img];
[self.view sendSubviewToBack:img];

2.扫描相册中二维码图片

在网上寻找了很久，发现AVFoundation.framework框架并不支持扫描相册中二维码图片功能。

于是，开始寻找支持扫描相册中二维码图片的第三方类库，目前只有ZBar和ZXingObjC支持，而前者很久没更新，故而选择后者。

通过以下代码可以实现点击相册，选择图片，获取图片中的二维码信息。

- (IBAction)clickPhotoAlbum:(id)sender
{
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.allowsEditing = YES;
picker.delegate = self;
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
[self presentViewController:picker animated:YES completion:^{}];
}
#pragma mark - UIImagePickerControllerDelegate
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
UIImage *image = [info objectForKey:@"UIImagePickerControllerEditedImage"];
[self dismissViewControllerAnimated:YES completion:^{
[self getURLWithImage:image];
}
];

}
-(void)getURLWithImage:(UIImage *)img{

UIImage *loadImage= img;
CGImageRef imageToDecode = loadImage.CGImage;

ZXLuminanceSource *source = [[ZXCGImageLuminanceSource alloc] initWithCGImage:imageToDecode];
ZXBinaryBitmap *bitmap = [ZXBinaryBitmap binaryBitmapWithBinarizer:[ZXHybridBinarizer binarizerWithSource:source]];

NSError *error = nil;

ZXDecodeHints *hints = [ZXDecodeHints hints];

ZXMultiFormatReader *reader = [ZXMultiFormatReader reader];
ZXResult *result = [reader decode:bitmap
hints:hints
error:&error];
if (result) {
// The coded result as a string. The raw data can be accessed with
// result.rawBytes and result.length.
NSString *contents = result.text;
NSLog(@"contents =%@",contents);
UIAlertView *alter = [[UIAlertView alloc] initWithTitle:@"解析成功" message:contents delegate:nil cancelButtonTitle:@"确定" otherButtonTitles: nil];
[alter show];

} else {
UIAlertView *alter1 = [[UIAlertView alloc] initWithTitle:@"解析失败" message:nil delegate:nil cancelButtonTitle:@"确定" otherButtonTitles: nil];
[alter1 show];
}
}

但，以上代码存在一点小问题，跳转到相册后，选择一张图片，这张图片是可编辑的状态

picker.allowsEditing = YES;

改为

picker.allowsEditing = NO;

结果，闪退。调试发现跳转到以下代码，image为空。

UIImage *image = [info objectForKey:@"UIImagePickerControllerEditedImage"];

打印info，发现info中还有UIImagePickerControllerOriginalImage，将image该为UIImagePickerControllerOriginalImage即可。

UIImage *image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];

3.开灯

这里的开灯其实就是打开手电筒，手电筒也是基于AVFoundation.framework框架，通过以下代码可以实现开灯和关灯功能。

- (IBAction)clickLight:(id)sender {
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if ([device hasTorch]) {
[device lockForConfiguration:nil];
if(isLedOn){
//关灯
[device setTorchMode: AVCaptureTorchModeOff];
}else{
//开灯
[device setTorchMode: AVCaptureTorchModeOn];
}

[device unlockForConfiguration];
}
isLedOn = !isLedOn;
}

但是，光有以上代码是不够的，在离开扫一扫界面时，如果没有关闭手电筒，手电筒一直会是开启的状态。这时，需要添加以下代码，在离开页面时，关闭手电筒。

-(void)viewWillDisappear:(BOOL)animated{
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if ([device hasTorch]) {
[device lockForConfiguration:nil];
[device setTorchMode: AVCaptureTorchModeOff];

[device unlockForConfiguration];
}
isLedOn = NO;
}

以上三部分代码，即可完成类似qq扫一扫功能。