ios 原生二维码扫描以及需要注意事项

最近在研究ios的二维码扫描功能，网上有好多诸如ZXing,ZBar第三方类库的介绍，如果仅仅是为了扫码，我觉得使用第三方类库有些麻烦，其实ios提供了二维码扫描的api，不多说了，直接上代码

//

// ViewController.m

// Quickmark

//

// Created by chengpengfei on 15/10/22.

// Copyright © 2015年 LIONTECH TECHNOLOGY CO.,LTD. All rights reserved.

//

#import <UIKit/UIKit.h>

#import <AVFoundation/AVFoundation.h>

#import "CJMScanController.h"

#import "LTBottomView.h"

@interface
CJMScanController ()<AVCaptureMetadataOutputObjectsDelegate>

@property ( strong ,
nonatomic ) AVCaptureDevice * device;

@property ( strong ,
nonatomic ) AVCaptureDeviceInput * input;

@property ( strong ,
nonatomic ) AVCaptureMetadataOutput * output;

@property ( strong ,
nonatomic ) AVCaptureSession * session;

@property (
strong , nonatomic )
AVCaptureVideoPreviewLayer * preview;

@end

@implementation CJMScanController

@synthesize session;

- (void)viewDidLoad {

[super
viewDidLoad];

self.view.backgroundColor = [UIColor
whiteColor];

UINavigationBar *bar = [[UINavigationBar
alloc]
initWithFrame:CGRectMake(0,
0, self.view.frame.size.width,64)];

bar.barTintColor = [UIColor
yellowColor];

UINavigationItem *navigationItem = [[UINavigationItem
alloc]
initWithTitle:@"扫描二维码"];

[bar pushNavigationItem:navigationItem
animated:YES];

UIBarButtonItem *rightItem = [[UIBarButtonItem
alloc] initWithTitle:@"取消"
style:UIBarButtonItemStyleDone
target:self
action:@selector(cancleScan)];

navigationItem.rightBarButtonItem = rightItem;

[self.view
addSubview:bar];

// 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=@[AVMetadataObjectTypeAztecCode,AVMetadataObjectTypeCode128Code,AVMetadataObjectTypeCode39Code,AVMetadataObjectTypeCode39Mod43Code,AVMetadataObjectTypeCode93Code,AVMetadataObjectTypeDataMatrixCode,AVMetadataObjectTypeEAN13Code,AVMetadataObjectTypeEAN8Code,AVMetadataObjectTypeFace,AVMetadataObjectTypeInterleaved2of5Code,AVMetadataObjectTypeITF14Code,AVMetadataObjectTypePDF417Code,AVMetadataObjectTypeQRCode,AVMetadataObjectTypeUPCECode];

CGFloat width = [UIScreen
mainScreen].bounds.size.width;

CGFloat height = [UIScreen mainScreen].bounds.size.height;

CGFloat w1 = 250/width;

CGFloat h1 = 250/height;

CGFloat w2 = (1-w1)/2;

CGFloat h2 = 64/height+(height-250-64)/(height*2);

output.rectOfInterest = CGRectMake(h2,w2, h1, w1);

LTBottomView*bView = [[LTBottomView alloc] initWithFrame:CGRectMake(0,
64, width, height-64)];

bView.backgroundColor = [UIColor clearColor];

bView.buttomColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:0.8];

bView.cutRect = CGRectMake((1-w2-w1)*width, h2*height-64, width*w1, height*h1);

[self.view addSubview:bView];

AVCaptureVideoPreviewLayer * layer = [AVCaptureVideoPreviewLayer layerWithSession:session];

layer.videoGravity=AVLayerVideoGravityResizeAspectFill;

layer.frame=CGRectMake(0,
0, width, height);

[self.view.layer insertSublayer:layer atIndex:0];

//开始捕获

[session startRunning];

}

-(void) cancleScan{

[self
dismissViewControllerAnimated:YES
completion:^{}];

}

-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection
*)connection{

NSString *stringValue;

if ([metadataObjects
count ] > 0 )

{

AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects
objectAtIndex : 0 ];

//输出扫描字符串

NSLog(@"%@",metadataObject.stringValue);

[session stopRunning];

[self
dismissViewControllerAnimated:YES
completion:^{

[self.delegate
scanFinished:self
content:metadataObject.stringValue];

}];

}

}

-(void)viewWillAppear:(BOOL)animated {

if (!session.isRunning) {

[session startRunning];

}

}

- (void)didReceiveMemoryWarning {

[super
didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

上面需要注意的是output.rectOfInterest的使用

output.rectOfInterest 是一个CGRect,即扫描区域，这个CGRect跟我们平常用的不同，我们平常使用CGRect一般使用CGRectMake(X,Y,W,H) X,Y,W,Z是任意值，但是在这里恰好反过来了

output.rectOfInterest = CGRectMake(Y,X,H,W);这里的Y,X,H,W是0-1的值，即比值，而且X,Y是以右上角为参考