這兩天用到了二維碼掃描功能，網上第三方框架是有，但是想弄清楚其原理，就自己用了系統原生的方法，其中部分地方有點坑，就記錄下來，權當下次使用提醒。
二維碼掃描
不多說，上代碼：
#import <AVFoundation/AVFoundation.h> //引用AVFoundation框架
@interface ViewController ()<AVCaptureMetadataOutputObjectsDelegate> //遵守AVCaptureMetadataOutputObjectsDelegate協議
@property ( strong , nonatomic ) AVCaptureDevice * device; //捕獲設備，默認后置攝像頭
@property ( strong , nonatomic ) AVCaptureDeviceInput * input; //輸入設備
@property ( strong , nonatomic ) AVCaptureMetadataOutput * output;//輸出設備，需要指定他的輸出類型及掃描范圍
@property ( strong , nonatomic ) AVCaptureSession * session; //AVFoundation框架捕獲類的中心樞紐，協調輸入輸出設備以獲得數據
@property ( strong , nonatomic ) AVCaptureVideoPreviewLayer * previewLayer;//展示捕獲圖像的圖層，是CALayer的子類
@property (nonatomic,strong)UIView *scanView;定位掃描框在哪個位置
初始化對象：
- (AVCaptureDevice *)device
{
if (_device == nil) {
// 設置AVCaptureDevice的類型為Video類型
_device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
}
return _device;
}
- (AVCaptureDeviceInput *)input
{
if (_input == nil) {
//輸入設備初始化
_input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];
}
return _input;
}
這里設置輸出設備要注意rectOfInterest屬性的設置，一般默認是CGRect(x: 0, y: 0, width: 1, height: 1),全屏都能讀取的，但是讀取速度較慢。注意rectOfInterest屬性的傳人的是比例。比例是根據掃描容器的尺寸比上屏幕尺寸（注意要計算的時候要計算導航欄高度，有的話需減去）。
參照的是橫屏左上角的比例，而不是豎屏。所以我們再設置的時候要調整方向如下面所示。
- (AVCaptureMetadataOutput *)output
{
if (_output == nil) {
//初始化輸出設備
_output = [[AVCaptureMetadataOutput alloc] init];
// 1.獲取屏幕的frame
CGRect viewRect = self.view.frame;
// 2.獲取掃描容器的frame
CGRect containerRect = self.scanView.frame;
CGFloat x = containerRect.origin.y / viewRect.size.height;
CGFloat y = containerRect.origin.x / viewRect.size.width;
CGFloat width = containerRect.size.height / viewRect.size.height;
CGFloat height = containerRect.size.width / viewRect.size.width;
//rectOfInterest屬性設置設備的掃描范圍
_output.rectOfInterest = CGRectMake(x, y, width, height);
}
return _output;
}
網上還有一種是根據AVCaptureInputPortFormatDescriptionDidChangeNotification通知設置的，也是可行的，自選一種即可。
__weak typeof(self) weakSelf = self;
[[NSNotificationCenter defaultCenter]addObserverForName:AVCaptureInputPortFormatDescriptionDidChangeNotification
object:nil
queue:[NSOperationQueue mainQueue]
usingBlock:^(NSNotification * _Nonnull note) {
if (weakSelf){
//調整掃描區域
AVCaptureMetadataOutput *output = weakSelf.session.outputs.firstObject;
output.rectOfInterest = [weakSelf.previewLayer metadataOutputRectOfInterestForRect:weakSelf.scanView.frame];
}
}];
下面初始化AVCaptureSession和AVCaptureVideoPreviewLayer:
- (AVCaptureSession *)session
{
if (_session == nil) {
_session = [[AVCaptureSession alloc] init];
}
return _session;
}
- (AVCaptureVideoPreviewLayer *)previewLayer
{
if (_previewLayer == nil) {
//負責圖像渲染出來
_previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.session];
self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
}
return _previewLayer;
}
接著我們再viewDidLoad中初始化并啟動掃描
- (void)viewDidLoad {
[super viewDidLoad];
CGFloat kScreen_Width = [UIScreen mainScreen].bounds.size.width;
//定位掃描框在屏幕正中央，并且寬高為200的正方形
self.scanView = [[UIView alloc]initWithFrame:CGRectMake((kScreen_Width-200)/2, (self.view.frame.size.height-200)/2, 200, 200)];
[self.view addSubview:self.scanView];
//設置掃描界面（包括掃描界面之外的部分置灰，掃描邊框等的設置）,后面設置
TNWCameraScanView *clearView = [[TNWCameraScanView alloc]initWithFrame:self.view.frame];
[self.view addSubview:clearView];
[self startScan];
}
- (void)startScan
{
// 1.判斷輸入能否添加到會話中
if (![self.session canAddInput:self.input]) return;
[self.session addInput:self.input];
// 2.判斷輸出能夠添加到會話中
if (![self.session canAddOutput:self.output]) return;
[self.session addOutput:self.output];
// 4.設置輸出能夠解析的數據類型
// 注意點: 設置數據類型一定要在輸出對象添加到會話之后才能設置
//設置availableMetadataObjectTypes為二維碼、條形碼等均可掃描，如果想只掃描二維碼可設置為
// [self.output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];
self.output.metadataObjectTypes = self.output.availableMetadataObjectTypes;
// 5.設置監聽監聽輸出解析到的數據
[self.output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
// 6.添加預覽圖層
[self.view.layer insertSublayer:self.previewLayer atIndex:0];
self.previewLayer.frame = self.view.bounds;
// 8.開始掃描
[self.session startRunning];
}
下面是接收掃描結果的代理AVCaptureMetadataOutputObjectsDelegate:
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
[self.session stopRunning]; //停止掃描
//我們捕獲的對象可能不是AVMetadataMachineReadableCodeObject類，所以要先判斷，不然會崩潰
if (![[metadataObjects lastObject] isKindOfClass:[AVMetadataMachineReadableCodeObject class]]) {
[self.session startRunning];
return;
}
// id 類型不能點語法,所以要先去取出數組中對象
AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];
if ( object.stringValue == nil ){
[self.session startRunning];
}
上面就是常用的二維碼掃描部分的代碼，我們下面再簡單的看下它掃描框之外界面的設置（包括掃描界面之外的部分置灰，掃描邊框等）。具體樣式你們可以自己調整添加。
掃描框
@interface TNWCameraScanView : UIView
- (instancetype)initWithFrame:(CGRect)frame;
@end
#import "TNWCameraScanView.h"
@interface TNWCameraScanView()
{
CGFloat sceenHeight;
NSTimer *timer;
CGRect scanRect;
CGFloat kScreen_Width;
CGFloat kScreen_Height;
}
@property (nonatomic,assign)CGFloat lineWidth;
@property (nonatomic,assign)CGFloat height;
@property (nonatomic,strong)UIColor *lineColor;
@property (nonatomic, assign)CGFloat scanTime;
@end
@implementation TNWCameraScanView
- (instancetype)initWithFrame:(CGRect)frame{
if (self = [super initWithFrame:frame]) {
self.backgroundColor = [UIColor clearColor]; // 清空背景色，否則為黑
sceenHeight =self.frame.size.height;
_height = 200; // 寬高200的正方形
_lineWidth = 2; // 掃描框4個腳的寬度
_lineColor = [UIColor greenColor]; // 掃描框4個腳的顏色
_scanTime = 3; //掃描線的時間間隔設置
kScreen_Width = [UIScreen mainScreen].bounds.size.width;
kScreen_Height = [UIScreen mainScreen].bounds.size.height;
[self scanLineMove];
//定時，多少秒掃描線刷新一次
timer = [NSTimer scheduledTimerWithTimeInterval:_scanTime target:self selector:@selector(scanLineMove) userInfo:nil repeats:YES];
}
return self;
}
- (void)scanLineMove{
UIView *line = [[UIView alloc]initWithFrame:CGRectMake((kScreen_Width-_height)/2, (sceenHeight-_height)/2, _height, 1)];
line.backgroundColor = [UIColor greenColor];
[self addSubview:line];
[UIView animateWithDuration:_scanTime animations:^{
line.frame = CGRectMake((kScreen_Width-_height)/2, (sceenHeight+_height)/2, _height, 0.5);
} completion:^(BOOL finished) {
[line removeFromSuperview];
}];
}
-(void)drawRect:(CGRect)rect{
CGFloat bottomHeight = (sceenHeight-_height)/2;
CGFloat leftWidth = (kScreen_Width-_height)/2;
CGContextRef ctx = UIGraphicsGetCurrentContext();
//設置4個方向的灰度值，透明度為0.5，可自行調整。
CGContextSetRGBFillColor(ctx, 0, 0, 0, 0.5);
CGContextFillRect(ctx, CGRectMake(0, 0, kScreen_Width, bottomHeight));
CGContextStrokePath(ctx);
CGContextFillRect(ctx, CGRectMake(0,bottomHeight, leftWidth, _height));
CGContextStrokePath(ctx);
CGContextFillRect(ctx, CGRectMake((kScreen_Width+_height)/2, bottomHeight, leftWidth, _height));
CGContextStrokePath(ctx);
CGContextFillRect(ctx, CGRectMake(0,(sceenHeight+_height)/2, kScreen_Width, bottomHeight));
CGContextStrokePath(ctx);
//掃描框4個腳的設置
CGContextSetLineWidth(ctx, _lineWidth);
CGContextSetStrokeColorWithColor(ctx, _lineColor.CGColor);
//左上角
CGContextMoveToPoint(ctx, leftWidth, bottomHeight+30);
CGContextAddLineToPoint(ctx, leftWidth, bottomHeight);
CGContextAddLineToPoint(ctx, leftWidth+30, bottomHeight);
CGContextStrokePath(ctx);
//右上角
CGContextMoveToPoint(ctx, (kScreen_Width+_height)/2-30, bottomHeight);
CGContextAddLineToPoint(ctx, (kScreen_Width+_height)/2, bottomHeight);
CGContextAddLineToPoint(ctx, (kScreen_Width+_height)/2, bottomHeight+30);
CGContextStrokePath(ctx);
//左下角
CGContextMoveToPoint(ctx, leftWidth, (sceenHeight+_height)/2-30);
CGContextAddLineToPoint(ctx, leftWidth, (sceenHeight+_height)/2);
CGContextAddLineToPoint(ctx, leftWidth+30, (sceenHeight+_height)/2);
CGContextStrokePath(ctx);
//右下角
CGContextMoveToPoint(ctx, (kScreen_Width+_height)/2-30, (sceenHeight+_height)/2);
CGContextAddLineToPoint(ctx, (kScreen_Width+_height)/2, (sceenHeight+_height)/2);
CGContextAddLineToPoint(ctx, (kScreen_Width+_height)/2, (sceenHeight+_height)/2-30);
CGContextStrokePath(ctx);
設置掃描框4個邊的顏色和線框。
// CGContextSetStrokeColorWithColor(ctx, [UIColor whiteColor].CGColor);
// CGContextSet_lineWidth(ctx, 1);
// CGContextAddRect(ctx, CGRectMake(leftWidth, bottomHeight, height, height));
// CGContextStrokePath(ctx);
scanRect = CGRectMake(leftWidth, bottomHeight, _height, _height);
}
- (void)dealloc{
//清除計時器
[timer invalidate];
timer = nil;
}
掃描相冊中的二維碼
再說一下關于掃描相冊中的二維碼部分，使用CIDetector進行圖片解析，比較簡單。
- (void)choicePhoto{
//調用相冊
UIImagePickerController *imagePicker = [[UIImagePickerController alloc]init];
//UIImagePickerControllerSourceTypePhotoLibrary為相冊
imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
//設置代理UIImagePickerControllerDelegate和UINavigationControllerDelegate
imagePicker.delegate = self;
[self presentViewController:imagePicker animated:YES completion:nil];
}
//選中圖片的回調
-(void)imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
//取出選中的圖片
UIImage *pickImage = info[UIImagePickerControllerOriginalImage];
NSData *imageData = UIImagePNGRepresentation(pickImage);
CIImage *ciImage = [CIImage imageWithData:imageData];
//創建探測器
//CIDetectorTypeQRCode表示二維碼，這里選擇CIDetectorAccuracyLow識別速度快
CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{CIDetectorAccuracy: CIDetectorAccuracyLow}];
NSArray *feature = [detector featuresInImage:ciImage];
//取出探測到的數據
for (CIQRCodeFeature *result in feature) {
NSString *content = result.messageString;// 這個就是我們想要的值
}
[self dismissViewControllerAnimated:YES completion:nil];
}
常用的二維碼或條形碼就是這些吧，后續再進行補充。
