iOS中 扫描二维码/生成二维码具体解释 韩俊强的博客

近期大家总是问我有没有关于二维码的demo,为了满足大家的需求,特此研究了一番,希望能帮到大家!

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指示根视图:

 self.window.rootViewController = [[UINavigationController alloc]initWithRootViewController:[SecondViewController new]];

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生成二维码:

//  Created by 韩俊强 on 15/11/27.
//  Copyright (c) 2015年 韩俊强. All rights reserved.
//

#import "SecondViewController.h"

@interface SecondViewController ()

@property (nonatomic, strong) UITextField *tfCode;
@property (nonatomic, strong) UIButton *btnGenerate;
@property (nonatomic, strong) UIImageView *imageView;
@end

@implementation SecondViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    CGSize windowSize = [UIScreen mainScreen].bounds.size;
    
    self.tfCode = [[UITextField alloc] initWithFrame:CGRectMake(10, 64, windowSize.width-100, 40)];
    [self.view addSubview:self.tfCode];
    self.tfCode.borderStyle = UITextBorderStyleRoundedRect;
    
    self.btnGenerate = [[UIButton alloc] initWithFrame:CGRectMake(windowSize.width-100, 64, 90, 40)];
    [self.view addSubview:self.btnGenerate];
    [self.btnGenerate addTarget:self action:@selector(actionGenerate) forControlEvents:UIControlEventTouchUpInside];
    self.btnGenerate.backgroundColor = [UIColor lightGrayColor];
    [self.btnGenerate setTitle:@"生成" forState:UIControlStateNormal];
    [self.btnGenerate setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    
    self.imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 300, 300)];
    [self.view addSubview:self.imageView];
    self.imageView.center = CGPointMake(windowSize.width/2, windowSize.height/2);
    
    self.tfCode.text = @"http://www.baidu.com";
}
- (void)actionGenerate
{
    NSString *text = self.tfCode.text;
    
    NSData *stringData = [text dataUsingEncoding: NSUTF8StringEncoding];
    
    //生成
    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    [qrFilter setValue:stringData forKey:@"inputMessage"];
    [qrFilter setValue:@"M" forKey:@"inputCorrectionLevel"];
    
    UIColor *onColor = [UIColor blackColor];
    UIColor *offColor = [UIColor whiteColor];
    
    //上色
    CIFilter *colorFilter = [CIFilter filterWithName:@"CIFalseColor" keysAndValues:@"inputImage",qrFilter.outputImage,@"inputColor0",[CIColor colorWithCGColor:onColor.CGColor],@"inputColor1",[CIColor colorWithCGColor:offColor.CGColor],nil];
    
    CIImage *qrImage = colorFilter.outputImage;
    
    //绘制
    CGSize size = CGSizeMake(300, 300);
    CGImageRef cgImage = [[CIContext contextWithOptions:nil] createCGImage:qrImage fromRect:qrImage.extent];
    UIGraphicsBeginImageContext(size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetInterpolationQuality(context, kCGInterpolationNone);
    CGContextScaleCTM(context, 1.0, -1.0);
    CGContextDrawImage(context, CGContextGetClipBoundingBox(context), cgImage);
    UIImage *codeImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    CGImageRelease(cgImage);
    
    self.imageView.image = codeImage;
}

扫描二维码:

//  Created by 韩俊强 on 15/11/27.
//  Copyright (c) 2015年 韩俊强. All rights reserved.
//

#import "RootViewController.h"
#import <AVFoundation/AVFoundation.h>

@interface RootViewController ()<AVCaptureMetadataOutputObjectsDelegate,UIAlertViewDelegate>

@property (nonatomic, strong) UIView *scanRectView;
// 硬件设备
@property (strong, nonatomic) AVCaptureDevice            *device;
//输入设备
@property (strong, nonatomic) AVCaptureDeviceInput       *input;
//输出设备
@property (strong, nonatomic) AVCaptureMetadataOutput    *output;
//桥梁.连接输入和输出设备,
@property (strong, nonatomic) AVCaptureSession           *session;
@property (strong, nonatomic) AVCaptureVideoPreviewLayer *preview;

@end

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    CGSize windowSize = [UIScreen mainScreen].bounds.size;
    
    CGSize scanSize = CGSizeMake(windowSize.width*3/4, windowSize.width*3/4);
    CGRect scanRect = CGRectMake((windowSize.width-scanSize.width)/2, (windowSize.height-scanSize.height)/2, scanSize.width, scanSize.height);
    
    scanRect = CGRectMake(scanRect.origin.y/windowSize.height, scanRect.origin.x/windowSize.width, scanRect.size.height/windowSize.height,scanRect.size.width/windowSize.width);
    
    self.device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    
    self.input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];
    
    self.output = [[AVCaptureMetadataOutput alloc]init];
    [self.output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    
    self.session = [[AVCaptureSession alloc]init];
    [self.session setSessionPreset:([UIScreen mainScreen].bounds.size.height<500)?
AVCaptureSessionPreset640x480:AVCaptureSessionPresetHigh];
    [self.session addInput:self.input];
    [self.session addOutput:self.output];
    self.output.metadataObjectTypes=@[AVMetadataObjectTypeQRCode];
    self.output.rectOfInterest = scanRect;
    
    self.preview = [AVCaptureVideoPreviewLayer layerWithSession:self.session];
    self.preview.videoGravity = AVLayerVideoGravityResizeAspectFill;
    self.preview.frame = [UIScreen mainScreen].bounds;
    [self.view.layer insertSublayer:self.preview atIndex:0];
    
    self.scanRectView = [UIView new];
    [self.view addSubview:self.scanRectView];
    self.scanRectView.frame = CGRectMake(0, 0, scanSize.width, scanSize.height);
    self.scanRectView.center = CGPointMake(CGRectGetMidX([UIScreen mainScreen].bounds), CGRectGetMidY([UIScreen mainScreen].bounds));
    self.scanRectView.layer.borderColor = [UIColor redColor].CGColor;
    self.scanRectView.layer.borderWidth = 1;
    
    
    //開始捕获
    [self.session startRunning];
    
}


- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    if ( (metadataObjects.count==0) )
    {
        return;
    }
    
    if (metadataObjects.count>0) {
        
        [self.session stopRunning];
        
        AVMetadataMachineReadableCodeObject *metadataObject = metadataObjects.firstObject;
        //输出扫描字符串
        
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:metadataObject.stringValue message:@"" delegate:self cancelButtonTitle:@"ok" otherButtonTitles: nil];
        
        [alert show];
    }
}

- (void)alertView:(UIAlertView *)alertView willDismissWithButtonIndex:(NSInteger)buttonIndex
{
    [self.session startRunning];
}

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终于效果:(因为扫描二维码无法展示效果,所以自己动手真机測试吧!)

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IOS7之前，开发人员进行扫码编程时，通常会借助第三方库。经常使用的是ZBarSDK。IOS7之后，系统的AVMetadataObject类中，为我们提供了解析二维码的接口。经过測试。使用原生API扫描和处理的效率很高。远远高于第三方库。

一、用法演示样例

官方提供的接口很easy，代码例如以下：

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@interface ViewController ()<AVCaptureMetadataOutputObjectsDelegate>//用于处理採集信息的代理 {     AVCaptureSession * session;//输入输出的中间桥梁 } @end @implementation ViewController   - (void)viewDidLoad {     [super viewDidLoad];     // Do any additional setup after loading the view, typically from a nib.     //获取摄像设备     AVCaptureDevice * device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];     //创建输入流     AVCaptureDeviceInput * input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];     //创建输出流     AVCaptureMetadataOutput * output = [[AVCaptureMetadataOutput alloc]init];     //设置代理 在主线程里刷新     [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];           //初始化链接对象     session = [[AVCaptureSession alloc]init];     //高质量採集率     [session setSessionPreset:AVCaptureSessionPresetHigh];           [session addInput:input];     [session addOutput:output];     //设置扫码支持的编码格式(例如以下设置条形码和二维码兼容)     output.metadataObjectTypes=@[AVMetadataObjectTypeQRCode,AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode128Code];              AVCaptureVideoPreviewLayer * layer = [AVCaptureVideoPreviewLayer layerWithSession:session];     layer.videoGravity=AVLayerVideoGravityResizeAspectFill;     layer.frame=self.view.layer.bounds;     [self.view.layer insertSublayer:layer atIndex:0];     //開始捕获     [session startRunning]; }

之后我们的UI上已经能够看到摄像头捕获的内容，仅仅要实现代理中的方法，就能够完毕二维码条形码的扫描：

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-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{     if (metadataObjects.count>0) {         //[session stopRunning];         AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects objectAtIndex : 0 ];         //输出扫描字符串         NSLog(@"%@",metadataObject.stringValue);     } }

二、一些优化

通过上面的代码測试，我们能够发现系统的解析处理效率是相当的高。IOS官方提供的API也确实很强大，然而。我们能够做进一步的优化，将效率更加提高：

首先。AVCaptureMetadataOutput类中有一个这种属性(在IOS7.0之后可用)：

@property(nonatomic) CGRect rectOfInterest;

这个属性大致意思就是告诉系统它须要注意的区域，大部分APP的扫码UI中都会有一个框。提醒你将条形码放入那个区域，这个属性的作用就在这里。它能够设置一个范围。仅仅处理在这个范围内捕获到的图像的信息。

如此一来。可想而知，我们代码的效率又会得到非常大的提高。在使用这个属性的时候。须要几点注意：

1、这个CGRect參数和普通的Rect范围不太一样。它的四个值的范围都是0-1，表示比例。

2、经过測试发现，这个參数里面的x相应的恰恰是距离左上角的垂直距离。y相应的是距离左上角的水平距离。

3、宽度和高度设置的情况也是类似。

3、举个样例假设我们想让扫描的处理区域是屏幕的下半部分。我们这样设置

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1	output.rectOfInterest=CGRectMake(0.5,0,0.5, 1);

详细apple为什么要设计成这样，或者是这个參数我的使用方法那里不正确，还须要了解的朋友给个指导。

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