title : IOS中生成二维码、扫描二维码
category : UI

IOS中生成二维码、保存二维码

标签（空格分隔）： IOS

[TOC]

简介

• 从IOS7开始集成了二维码的生成和读取功能

生成二维码

• 1 导入CoreImage框架
  #import <CoreImage/CoreImage.h>

• 2 通过滤镜CIFilter生成二维码

/**
 *  生成二维码
 */
- (void)creatCIQRCodeImage
{
    // 1.创建过滤器，这里的@"CIQRCodeGenerator"是固定的
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    
    // 2.恢复默认设置
    [filter setDefaults];
    
    // 3. 给过滤器添加数据
    NSString *dataString = @"二维码测试数据";
    NSData *data = [dataString dataUsingEncoding:NSUTF8StringEncoding];
    // 注意，这里的value必须是NSData类型
    [filter setValue:data forKeyPath:@"inputMessage"];
    
    // 4. 生成二维码
    CIImage *outputImage = [filter outputImage];
    
    // 5. 显示二维码
    self.imageView.image = [UIImage imageWithCIImage:outputImage];
}

• 通过上述方法生成的二维码图片比较模糊，第5步显示二维码的时候可以调用以下方法生成比较清晰的二维码

/**
 *  根据CIImage生成指定大小的UIImage
 *
 *  @param image CIImage
 *  @param size  图片宽度
 *
 *  @return 生成高清的UIImage
 */
- (UIImage *)creatNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat)size
{
    CGRect extent = CGRectIntegral(image.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
    
    // 1. 创建bitmap
    size_t width = CGRectGetWidth(extent) * scale;
    size_t height = CGRectGetHeight(extent) * scale;
    CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();
    CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);
    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
    CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
    CGContextScaleCTM(bitmapRef, scale, scale);
    CGContextDrawImage(bitmapRef, extent, bitmapImage);
    
    // 2.保存bitmap图片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}

• 将上述生成高清二维码的方法封装成UIImage的Category如下

.h文件

#import <UIKit/UIKit.h>

@interface UIImage (Category)

/**
 *  根据CIImage生成指定大小的UIImage
 *
 *  @param image CIImage
 *  @param size  图片宽度
 *
 *  @return 生成的高清的UIImage
 */
+ (UIImage *)creatNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat)size;

@end

.m文件

#import "UIImage+Category.h"

@implementation UIImage (Category)
/**
 *  根据CIImage生成指定大小的UIImage
 *
 *  @param image CIImage
 *  @param size  图片宽度
 *
 *  @return 生成的高清的UIImage
 */
+ (UIImage *)creatNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat)size
{
    CGRect extent = CGRectIntegral(image.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
    
    // 1. 创建bitmap
    size_t width = CGRectGetWidth(extent) * scale;
    size_t height = CGRectGetHeight(extent) * scale;
    CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();
    CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);
    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
    CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
    CGContextScaleCTM(bitmapRef, scale, scale);
    CGContextDrawImage(bitmapRef, extent, bitmapImage);
    
    // 2.保存bitmap图片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}
@end

扫描二维码

• 1 导入<AVFoundation/AVFoundation.h>
• 2 扫描二维码实现

#import "ViewController.h"
// 导入<AVFoundation/AVFoundation.h>框架
#import <AVFoundation/AVFoundation.h>

@interface ViewController ()<AVCaptureMetadataOutputObjectsDelegate>
/** 捕捉会话 */
@property (nonatomic, weak) AVCaptureSession *session;
/** 预览图层 */
@property (nonatomic, weak) AVCaptureVideoPreviewLayer *layer;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // 扫描二维码
    [self scanCIQRCode];
}

/**
 *  扫描二维码
 */
- (void)scanCIQRCode
{
    // 1. 创建捕捉会话
    AVCaptureSession *session = [[AVCaptureSession alloc] init];
    self.session = session;
    
    // 2. 添加输入设备(数据从摄像头输入)
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
    [session addInput:input];
    
    // 3. 添加输出数据接口
    AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
    // 设置输出接口代理
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    [session addOutput:output];
    // 3.1 设置输入元数据的类型(类型是二维码数据)
    // 注意，这里必须设置在addOutput后面，否则会报错
    [output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];
    
    // 4.添加扫描图层
    AVCaptureVideoPreviewLayer *layer = [AVCaptureVideoPreviewLayer layerWithSession:session];
    layer.frame = self.view.bounds;
    [self.view.layer addSublayer:layer];
    self.layer = layer;
    
    // 5. 开始扫描
    [session startRunning];
}

#pragma mark - <AVCaptureMetadataOutputObjectsDelegate>

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    if (metadataObjects.count) {// 扫描到了数据
        AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];
        
        // 停止扫描
        [self.session stopRunning];
        
        // 将预览图层移除
        [self.layer removeFromSuperlayer];
    }else{
        NSLog(@"没有扫描到数据");
    }
}

@end

推荐文章：http://www.jianshu.com/p/7a0a8c8703d3

推荐文章：http://zhangbuhuai.com/2015/02/11/iOS%E5%8E%9F%E7%94%9F%E4%BA%8C%E7%BB%B4%E7%A0%81%E6%89%AB%E6%8F%8F/

Swift二维码扫描：https://github.com/ConanMTHu/QRCodeByAVFoundation