iOS 原生二维码[扫码]与[生成]详解

太过爱你忘了你带给我的痛 2022-06-12 00:25 385阅读 0赞

## 本文来自简书，原文地址:[http://www.jianshu.com/p/2180e940a589][http_www.jianshu.com_p_2180e940a589] ##

## 前言 ##

二维码现在很常见, App中有许多都配置了该功能, 网上也有很多对iOS二维码的讲解, 但是对配置扫码范围这个问题好像都没怎么讲清晰. 作者今天就写一下二维码.

## 一 二维码介绍 ##

![1240][]

二维码

三个回形大方块, 是为了给相机定位的; 黑白块, 黑块代表1, 白块代表0, 八个一组, 组成二进制信息. [科普：二维码是什么原理？][Link 1] 这个小视频, 简单介绍了下二维码.

![1240 1][]

原理图

## 二 iOS 扫码二维码 ##

*  一.工程中General -> Linked Frameworks and Libraries -> 引入 AVFoundation.framework
 *  二. 代码部分解析

1) 头文件

//引入头文件 #import <AVFoundation/AVFoundation.h> // 作者自定义的View视图, 继承UIView #import "ShadowView.h" #define kWidth [UIScreen mainScreen].bounds.size.width #define kHeight [UIScreen mainScreen].bounds.size.height #define customShowSize CGSizeMake(200, 200);

2) 定义属性

// ScanCodeViewController是作者创建的VC , 用Navi推出, 写入协议 (UIImagePickerControllerDelegate, UINavigationControllerDelegate 是为了 可以直接扫码图库中的二维码, 在Navi右上角创建button)
    @interface ScanCodeViewController ()<AVCaptureMetadataOutputObjectsDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate>
    
    /** 输入数据源 */
    @property (nonatomic, strong) AVCaptureDeviceInput *input;
    /** 输出数据源 */
    @property (nonatomic, strong) AVCaptureMetadataOutput *output;
    /** 输入输出的中间桥梁 负责把捕获的音视频数据输出到输出设备中 */
    @property (nonatomic, strong) AVCaptureSession *session;
    /** 相机拍摄预览图层 */
    @property (nonatomic, strong) AVCaptureVideoPreviewLayer *layerView;
    /** 预览图层尺寸 */
    @property (nonatomic, assign) CGSize layerViewSize;
    /** 有效扫码范围 */
    @property (nonatomic, assign) CGSize showSize;
    /** 作者自定义的View视图 */
    @property (nonatomic, strong) ShadowView *shadowView;
    
    @end

3) 创建二维码扫码

-(void)creatScanQR{
    
    /** 创建输入数据源 */
            AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];  //获取摄像设备
            self.input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];  //创建输出流
    
    /** 创建输出数据源 */
            self.output = [[AVCaptureMetadataOutput alloc] init];
            [self.output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];  //设置代理 在主线程里刷新
    
    /** Session设置 */
            self.session = [[AVCaptureSession alloc] init];
            [self.session setSessionPreset:AVCaptureSessionPresetHigh];   //高质量采集
            [self.session addInput:self.input];
            [self.session addOutput:self.output];
            //设置扫码支持的编码格式
            self.output.metadataObjectTypes = @[AVMetadataObjectTypeQRCode,
                                            AVMetadataObjectTypeEAN13Code,
                                            AVMetadataObjectTypeEAN8Code,
                                            AVMetadataObjectTypeCode128Code];
    /** 扫码视图 */
             //扫描框的位置和大小
            self.layerView = [AVCaptureVideoPreviewLayer layerWithSession:self.session];
            self.layerView.videoGravity = AVLayerVideoGravityResizeAspectFill;
            self.layerView.frame = CGRectMake(0, 64, self.view.frame.size.width, self.view.frame.size.height - 64);
            // 将扫描框大小定义为属行, 下面会有调用
            self.layerViewSize = CGSizeMake(_layerView.frame.size.width, _layerView.frame.size.height);
    
    }
    
    #pragma mark - 实现代理方法, 完成二维码扫描
    -(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
    
        if (metadataObjects.count > 0) {
    
             // 停止动画, 看完全篇记得打开注释, 不然扫描条会一直有动画效果
            //[self.shadowView stopTimer];
    
            //停止扫描
            [self.session stopRunning];
    
            AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects objectAtIndex : 0 ];
            //输出扫描字符串
            NSLog(@"%@",metadataObject.stringValue);
            UIAlertView * alert = [[UIAlertView alloc]initWithTitle:@"提示" message:[NSString stringWithFormat:@"%@", metadataObject.stringValue] delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];
            [alert show];
        }
    }

4) 调用方法

- (void)viewDidLoad {
        [super viewDidLoad];
    
        self.view.backgroundColor = [UIColor whiteColor];
    
        //调用
        [self creatScanQR];
        //添加拍摄图层
        [self.view.layer addSublayer:self.layerView];
        //开始二维码
        [self.session startRunning];
    
        // Do any additional setup after loading the view.
    }

> 至此 二维码扫码完成 , 你会发现 整个屏幕都可以扫码二维码, 与微信的二维码扫码 差的太多. 下面开始个性化设置

5) 自定义阴影视图层

#import <UIKit/UIKit.h>
    
    @interface ShadowView : UIView
    
    @property (nonatomic, assign) CGSize showSize;
    - (void)stopTimer;
    
    @end

#import "ShadowView.h"
    
    @interface ShadowView ()
    
    @property (nonatomic, strong) UIImageView *lineView;
    @property (nonatomic, strong) NSTimer *timer;
    
    @end
    
    @implementation ShadowView
    
    - (instancetype)initWithFrame:(CGRect)frame
    {
        self = [super initWithFrame:frame];
        if (self) {
    
            self.backgroundColor = [UIColor clearColor];
            // 图片下方附上
            self.lineView  = [[UIImageView alloc] init];
            self.lineView.image = [UIImage imageNamed:@"line"];
            [self addSubview:self.lineView];
    
        }
        return self;
    }
    
    -(void)playAnimation{
    
        [UIView animateWithDuration:2.4 delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
    
            self.lineView .frame = CGRectMake((self.frame.size.width - self.showSize.width) / 2, (self.frame.size.height + self.showSize.height) / 2, self.showSize.width, 2);
    
        } completion:^(BOOL finished) {
            self.lineView .frame = CGRectMake((self.frame.size.width - self.showSize.width) / 2, (self.frame.size.height - self.showSize.height) / 2, self.showSize.width, 2);
        }];
    }
    
    - (void)stopTimer
    {
        [_timer invalidate];
        _timer = nil;    
    }
    
    -(void)layoutSubviews{
    
        [super layoutSubviews];
    
        self.lineView .frame = CGRectMake((self.frame.size.width - self.showSize.width) / 2, (self.frame.size.height - self.showSize.height) / 2, self.showSize.width, 2);
    
    
        if (!_timer) {
    
            [self playAnimation];
    
            /* 自动播放 */
            self.timer = [NSTimer scheduledTimerWithTimeInterval:2.5 target:self selector:@selector(playAnimation) userInfo:nil repeats:YES];
    
        }
    
    }
    
    -(void)drawRect:(CGRect)rect{
    
        [super drawRect:rect];
    
        CGContextRef ctx = UIGraphicsGetCurrentContext();
    
        // 整体颜色
        CGContextSetRGBFillColor(ctx, 0.15, 0.15, 0.15, 0.6);
        CGContextFillRect(ctx, rect);   //draw the transparent layer
    
        //中间清空矩形框
        CGRect clearDrawRect = CGRectMake((rect.size.width - self.showSize.width) / 2, (rect.size.height - self.showSize.height) / 2, self.showSize.width, self.showSize.height);
        CGContextClearRect(ctx, clearDrawRect);
    
        //边框
        CGContextStrokeRect(ctx, clearDrawRect);
        CGContextSetRGBStrokeColor(ctx, 1, 1, 1, 1);  //颜色
        CGContextSetLineWidth(ctx, 0.5);             //线宽
        CGContextAddRect(ctx, clearDrawRect);       //矩形
        CGContextStrokePath(ctx);
    
        [self addCornerLineWithContext:ctx rect:clearDrawRect];
    
    }
    
    - (void)addCornerLineWithContext:(CGContextRef)ctx rect:(CGRect)rect{
    
        float cornerWidth = 4.0;
    
        float cornerLong = 16.0;
    
        //画四个边角 线宽
        CGContextSetLineWidth(ctx, cornerWidth);
    
        //颜色
        CGContextSetRGBStrokeColor(ctx, 83 /255.0, 239/255.0, 111/255.0, 1);//绿色
    
        //左上角
        CGPoint poinsTopLeftA[] = {CGPointMake(rect.origin.x + cornerWidth/2, rect.origin.y),
                                   CGPointMake(rect.origin.x + cornerWidth/2, rect.origin.y + cornerLong)};
    
        CGPoint poinsTopLeftB[] = {CGPointMake(rect.origin.x, rect.origin.y + cornerWidth/2),
                                   CGPointMake(rect.origin.x + cornerLong, rect.origin.y + cornerWidth/2)};
    
        [self addLine:poinsTopLeftA pointB:poinsTopLeftB ctx:ctx];
    
    
        //左下角
        CGPoint poinsBottomLeftA[] = {CGPointMake(rect.origin.x + cornerWidth/2, rect.origin.y + rect.size.height - cornerLong),
                                      CGPointMake(rect.origin.x + cornerWidth/2, rect.origin.y + rect.size.height)};
    
        CGPoint poinsBottomLeftB[] = {CGPointMake(rect.origin.x, rect.origin.y + rect.size.height - cornerWidth/2),
                                      CGPointMake(rect.origin.x + cornerLong, rect.origin.y + rect.size.height - cornerWidth/2)};
    
        [self addLine:poinsBottomLeftA pointB:poinsBottomLeftB ctx:ctx];
    
    
        //右上角
        CGPoint poinsTopRightA[] = {CGPointMake(rect.origin.x+ rect.size.width - cornerLong, rect.origin.y + cornerWidth/2),
                                    CGPointMake(rect.origin.x + rect.size.width, rect.origin.y + cornerWidth/2 )};
    
        CGPoint poinsTopRightB[] = {CGPointMake(rect.origin.x+ rect.size.width - cornerWidth/2, rect.origin.y),
                                    CGPointMake(rect.origin.x + rect.size.width- cornerWidth/2, rect.origin.y + cornerLong)};
    
        [self addLine:poinsTopRightA pointB:poinsTopRightB ctx:ctx];
    
        //右下角
        CGPoint poinsBottomRightA[] = {CGPointMake(rect.origin.x+ rect.size.width - cornerWidth/2, rect.origin.y+rect.size.height - cornerLong),
                                       CGPointMake(rect.origin.x- cornerWidth/2 + rect.size.width, rect.origin.y +rect.size.height )};
    
        CGPoint poinsBottomRightB[] = {CGPointMake(rect.origin.x+ rect.size.width - cornerLong, rect.origin.y + rect.size.height - cornerWidth/2),
                                       CGPointMake(rect.origin.x + rect.size.width, rect.origin.y + rect.size.height - cornerWidth/2 )};
    
        [self addLine:poinsBottomRightA pointB:poinsBottomRightB ctx:ctx];
    
    
        CGContextStrokePath(ctx);
    }
    
    - (void)addLine:(CGPoint[])pointA pointB:(CGPoint[])pointB ctx:(CGContextRef)ctx {
    
        CGContextAddLines(ctx, pointA, 2);
        CGContextAddLines(ctx, pointB, 2);
    }
    
    
    @end

![1240 2][]

line.png

注意 : 如果你对应写demo了, 并且真机测试的系统在ios7 以上, 会发现也许扫描线的初始位置会出现问题. 给个小提示 layoutSubviews 被执行了两次. 留个小尾巴. 让大家思考.

传送门 : 上述边角画图方法, 作者引用 [Raul7777][] 并附上链接 , 作者进行了一下小改进 , 并添加注释. 如果对你有帮助, 请给他点个 Star

补充 : 扫描线动画, 用NSTimer, 偶尔手机处理卡顿下, 就会被坑. 作者看到有用CABasicAnimation 写的, 觉得挺好. 所以 提供下, 该方法

-(void)addAnimationAboutScan{
    
        self.lineView.hidden = NO;
        CABasicAnimation *animation = [ShadowView moveYTime:2.5 fromY:[NSNumber numberWithFloat:0] toY:[NSNumber numberWithFloat:(self.showSize.height-1)] rep:OPEN_MAX];
        [self.lineView.layer addAnimation:animation forKey:@"LineAnimation"];       
    }
    
    + (CABasicAnimation *)moveYTime:(float)time fromY:(NSNumber *)fromY toY:(NSNumber *)toY rep:(int)rep{
    
        CABasicAnimation *animationMove = [CABasicAnimation animationWithKeyPath:@"transform.translation.y"];
        [animationMove setFromValue:fromY];
        [animationMove setToValue:toY];
        animationMove.duration = time;
        animationMove.delegate = self;
        animationMove.repeatCount  = rep;
        animationMove.fillMode = kCAFillModeForwards;
        animationMove.removedOnCompletion = NO;
        animationMove.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
        return animationMove;
    }
    
    - (void)removeAnimationAboutScan{
    
        [self.lineView.layer removeAnimationForKey:@"LineAnimation"];
        self.lineView.hidden = YES;
    }

6) 回到ScanCodeViewController 配置扫码范围

> 重点: 这是作者最想讲的 . 附上官方介绍  
> rectOfInterest Property  
> A rectangle of interest for limiting the search area for visual metadata.  
> Discussion  
> The value of this property is a CGRect value that determines the object’s rectangle of interest for each frame of video.  
> The rectangle's origin is top left and is relative to the coordinate space of the device providing the metadata.  
> Specifying a rectangle of interest may improve detection performance for certain types of metadata. Metadata objects whose bounds do not intersect with therectOfInterest will not be returned.  
> The default value of this property is a rectangle of (0.0, 0.0, 1.0, 1.0).
> 
> 说明 :  
> 看到矩形的原点是左上角, 但是真正测试 你会发现却是在右上角, 因为扫码默认是横屏, 所以原右上角变成左上角, 原宽变成高, 原高变成宽. 取值是按照 摄像头分辨率 来取的比例 而不是屏幕的宽高比例.
> 
> 屏幕宽高比例:  
> iPhone4 : \[320 480\] ; iPhone5: \[320 568 \] ; iPhone 6 : \[375 667\] ; iPhone 6plus : \[414 736\].
> 
> 作者设置 AVCaptureSessionPresetHigh 所以机型分辨率均为 1920×1080. 所以除了iPhone4 基本上 屏幕宽高比 符合 分辨率的比例. 会有些许误差, 但影响不大. 如需支持包含iPhone4的所以机型 需要将 屏幕宽高与分辨率统一. 方法如下. 这样便将 ShadowView 中间清空的矩形框 与 有效扫码范围 对应上了.

/** 配置扫码范围 */
    -(void)allowScanRect{
    
    
        /** 扫描是默认是横屏, 原点在[右上角] * rectOfInterest = CGRectMake(0, 0, 1, 1); * AVCaptureSessionPresetHigh = 1920×1080 摄像头分辨率 * 需要转换坐标 将屏幕与 分辨率统一 */
    
        //剪切出需要的大小位置
        CGRect shearRect = CGRectMake((self.layerViewSize.width - self.showSize.width) / 2,
                                      (self.layerViewSize.height - self.showSize.height) / 2,
                                      self.showSize.height,
                                      self.showSize.height);
    
    
        CGFloat deviceProportion = 1920.0 / 1080.0;
        CGFloat screenProportion = self.layerViewSize.height / self.layerViewSize.width;
    
        //分辨率比> 屏幕比 ( 相当于屏幕的高不够)
        if (deviceProportion > screenProportion) {
            //换算出 分辨率比 对应的 屏幕高
            CGFloat finalHeight = self.layerViewSize.width * deviceProportion;
            // 得到 偏差值
            CGFloat addNum = (finalHeight - self.layerViewSize.height) / 2;
    
                                                  // (对应的实际位置 + 偏差值) / 换算后的屏幕高
            self.output.rectOfInterest = CGRectMake((shearRect.origin.y + addNum) / finalHeight,
                                                     shearRect.origin.x / self.layerViewSize.width,
                                                     shearRect.size.height/ finalHeight,
                                                     shearRect.size.width/ self.layerViewSize.width);
    
        }else{
    
            CGFloat finalWidth = self.layerViewSize.height / deviceProportion;
    
            CGFloat addNum = (finalWidth - self.layerViewSize.width) / 2;
    
            self.output.rectOfInterest = CGRectMake(shearRect.origin.y / self.layerViewSize.height,
                                                    (shearRect.origin.x + addNum) / finalWidth,
                                                    shearRect.size.height / self.layerViewSize.height,
                                                    shearRect.size.width / finalWidth);
        }
    
    }

7) 读取相册中二维码

> 注意事项 : ios8 以上系统才开放读取相册二维码功能(CIDetectorTypeQRCode), 所以如iPhone4 该功能实现不了, 需要有判断.

#pragma mark - 相册中读取二维码
    /* navi按钮实现 */
    -(void)takeQRCodeFromPic:(UIBarButtonItem *)leftBar{
    
    
    
        if ([[[UIDevice currentDevice] systemVersion] doubleValue] < 8) {
    
            UIAlertView * alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"请更新系统至8.0以上!" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];
            [alert show];
    
        }else{
    
            if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]){
    
                UIImagePickerController *pickerC = [[UIImagePickerController alloc] init];
                pickerC.delegate = self;
    
                pickerC.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;  //来自相册
    
                [self presentViewController:pickerC animated:YES completion:NULL];
    
            }else{
    
                UIAlertView * alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"设备不支持访问相册，请在设置->隐私->照片中进行设置！" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];
                [alert show];
            }
    
        }
    
    
    }
    
    - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
    {
        //1.获取选择的图片
        UIImage *image = info[UIImagePickerControllerEditedImage];
    
        if (!image) {
            image = info[UIImagePickerControllerOriginalImage];
        }
        //2.初始化一个监测器
        CIDetector*detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{ CIDetectorAccuracy : CIDetectorAccuracyHigh }];
    
        [picker dismissViewControllerAnimated:YES completion:^{
    
            //监测到的结果数组 放置识别完之后的数据
            NSArray *features = [detector featuresInImage:[CIImage imageWithCGImage:image.CGImage]];
            //判断是否有数据（即是否是二维码）
            if (features.count >=1) {
                /**结果对象 */
                CIQRCodeFeature *feature = [features objectAtIndex:0];
                NSString *scannedResult = feature.messageString;
    
                UIAlertView * alertView = [[UIAlertView alloc]initWithTitle:@"提示" message:scannedResult delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];
                [alertView show];
    
            }
            else{
                UIAlertView * alertView = [[UIAlertView alloc]initWithTitle:@"提示" message:@"该图片没有包含二维码！" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];
                [alertView show];
    
            }
        }];
    }

8) 重写调用

- (void)viewDidLoad {
        [super viewDidLoad];
    
        self.view.backgroundColor = [UIColor whiteColor];
    
        //显示范围
         self.showSize = customShowSize;
        //调用
        [self creatScanQR];
        //添加拍摄图层
        [self.view.layer addSublayer:self.layerView];
        //开始二维码
        [self.session startRunning];
        //设置可用扫码范围
        [self allowScanRect];
    
       //添加上层阴影视图
        self.shadowView = [[ShadowView alloc] initWithFrame:CGRectMake(0, 64, kWidth, kHeight - 64)];
        [self.view addSubview:self.shadowView];
        self.shadowView.showSize = self.showSize;
    
    
        //添加扫码相册按钮
         self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"相册中选" style:UIBarButtonItemStylePlain target:self action:@selector(takeQRCodeFromPic:)];
    
        // Do any additional setup after loading the view.
    }

8) 权限问题

> 权限问题 使用相机需要获取相应权限, 如用户未开启, 可以设置提醒, 留个小尾巴, 读者自行设置.

## 三 iOS 二维码生成 ##

[天听云道的 \[ iOS \] 生成二维码 系统方法][_ iOS _ _] 这篇文章写了, 挺简单, 生成的是高清二维码, 但是 在ios7系统上, 还是不清晰, 也就是说如果 你的程序支持到ios7 该方法有些问题.

[船长\_的 iOS的生成二维码（彩色+阴影）][iOS] 这篇文章写了, 支持ios7 系统, 高清二维码.

所以对二维码生成问题 作者就不赘述了. 对iOS中二维码的讲解完成.

## 四 三方二维码链接 ##

补充下三方传送门 : [https://github.com/MxABC/LBXScan][https_github.com_MxABC_LBXScan]  
[https://github.com/TheLevelUp/ZXingObjC][https_github.com_TheLevelUp_ZXingObjC]

[http_www.jianshu.com_p_2180e940a589]: http://www.jianshu.com/p/2180e940a589
[1240]: /images/20220612/81c50a93e35f4908aa66ee5eda79f52a.png
[Link 1]: http://url.cn/2CiHjdt
[1240 1]: /images/20220612/a6fa472afe7842b2a75ab9bd4c6e0bcf.png
[1240 2]: /images/20220612/40d34979978b43aaaa020b29bf04bafb.png
[Raul7777]: https://github.com/Raul7777/XHScanTool
[_ iOS _ _]: http://www.jianshu.com/p/5b66a3f28c89
[iOS]: http://www.jianshu.com/p/85e131155b79
[https_github.com_MxABC_LBXScan]: https://github.com/MxABC/LBXScan
[https_github.com_TheLevelUp_ZXingObjC]: https://github.com/TheLevelUp/ZXingObjC