最近公司項目需要實作一個類似qq掃一掃功能，該功能主要分為三個部分：掃一掃、掃描相冊中二維碼圖檔、開燈（我的二維碼不是主要功能）
1.掃一掃
iOS7以後，AVFoundation.framework架構支援掃一掃功能，詳細代碼，可以參考http://www.jianshu.com/p/6b7d54b3f88b
但該部落格中的代碼隻能簡單的實作掃一掃功能，周圍的背景并不是半透明的。
通過以下代碼可以實作中間透明，旁邊半透明的效果
-(void)setupBgView{
self.view.backgroundColor = [UIColor blackColor];
//繪制掃一掃背景，中間透明，旁邊半透明
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();
}
但以上代碼仍然存在一點小問題：這張背景圖檔是直接蓋在最上層，導緻掃一掃界面上的圖檔和文字效果不好（左圖）。
隻需将背景圖檔移到視圖的最上層即可（右圖）：
[self.view addSubview:img];
[self.view sendSubviewToBack:img];
2.掃描相冊中二維碼圖檔
在網上尋找了很久，發現AVFoundation.framework架構并不支援掃描相冊中二維碼圖檔功能。
于是，開始尋找支援掃描相冊中二維碼圖檔的第三方類庫，目前隻有ZBar和ZXingObjC支援，而前者很久沒更新，故而選擇後者。
通過以下代碼可以實作點選相冊，選擇圖檔，擷取圖檔中的二維碼資訊。
- (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:@"解析失敗" message:nil delegate:nil cancelButtonTitle:@"确定" otherButtonTitles: nil];
[alter1 show];
}
}
但，以上代碼存在一點小問題，跳轉到相冊後，選擇一張圖檔，這張圖檔是可編輯的狀态
picker.allowsEditing = YES;
改為
picker.allowsEditing = NO;
結果，閃退。調試發現跳轉到以下代碼，image為空。
UIImage *image = [info objectForKey:@"UIImagePickerControllerEditedImage"];
列印info，發現info中還有UIImagePickerControllerOriginalImage，将image該為UIImagePickerControllerOriginalImage即可。
UIImage *image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
3.開燈
這裡的開燈其實就是打開手電筒，手電筒也是基于AVFoundation.framework架構，通過以下代碼可以實作開燈和關燈功能。
- (IBAction)clickLight:(id)sender {
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if ([device hasTorch]) {
[device lockForConfiguration:nil];
if(isLedOn){
//關燈
[device setTorchMode: AVCaptureTorchModeOff];
}else{
//開燈
[device setTorchMode: AVCaptureTorchModeOn];
}
[device unlockForConfiguration];
}
isLedOn = !isLedOn;
}
但是，光有以上代碼是不夠的，在離開掃一掃界面時，如果沒有關閉手電筒，手電筒一直會是開啟的狀态。這時，需要添加以下代碼，在離開頁面時，關閉手電筒。
-(void)viewWillDisappear:(BOOL)animated{
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if ([device hasTorch]) {
[device lockForConfiguration:nil];
[device setTorchMode: AVCaptureTorchModeOff];
[device unlockForConfiguration];
}
isLedOn = NO;
}
以上三部分代碼，即可完成類似qq掃一掃功能。