iOS中扫描二维码/生成二维码详解韩俊强的博客

最近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;

    //开始捕获
    [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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最终效果:(由于扫描二维码无法展示效果,所以自己动手真机测试吧!)

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IOS7之前，开发者进行扫码编程时，一般会借助第三方库。常用的是ZBarSDK，IOS7之后，系统的AVMetadataObject类中，为我们提供了解析二维码的接口。经过测试，使用原生API扫描和处理的效率非常高，远远高于第三方库。

一、使用方法示例

官方提供的接口非常简单，代码如下：

@interface ViewController ()<AVCaptureMetadataOutputObjectsDelegate>//用于处理采集信息的代理

{

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];

//高质量采集率

[session setSessionPreset:AVCaptureSessionPresetHigh];

[session addInput:input];

[session addOutput:output];

//设置扫码支持的编码格式(如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];

//开始捕获

[session startRunning];

}

之后我们的UI上已经可以看到摄像头捕获的内容，只要实现代理中的方法，就可以完成二维码条形码的扫描：

-(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

通过上面的代码测试，我们可以发现系统的解析处理效率是相当的高，IOS官方提供的API也确实非常强大，然而，我们可以做进一步的优化，将效率更加提高：

首先，AVCaptureMetadataOutput类中有一个这样的属性(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需要注意的区域，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，它可以设置一个范围，只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很大的提高，在使用这个属性的时候。需要几点注意：

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

2、经过测试发现，这个参数里面的x对应的恰恰是距离左上角的垂直距离，y对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、举个例子如果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

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

具体apple为什么要设计成这样，或者是这个参数我的用法那里不对，还需要了解的朋友给个指导。

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