ios原生二维码扫描

做ios的二维码扫描，有两个第三方库可以选择，zbar和zxing。今天要介绍的是ios7.0后avfoundation框架提供的原生二维码扫描。

首先需要添加avfoundation.framework框架到你工程中build phase的"link binary with libraries"之下，然后就可以开始了。

一、做好准备工作，搭建ui

ui效果如图

iboutlet、ibaction如下：

@property (weak, nonatomic) iboutlet uiview *viewpreview;
@property (weak, nonatomic) iboutlet uilabel *lblstatus;
@property (weak, nonatomic) iboutlet uibutton *startbtn;
- (ibaction)startstopreading:(id)sender;

接下来就都是代码的事情了

二、控制器viewcontroller.h

首先导入avfoundation框架

#import <avfoundation/avfoundation.h>

然后控制器实现 avcapturemetadataoutputobjectsdelegate协议

@interface viewcontroller ()<avcapturemetadataoutputobjectsdelegate>

整体property如下：

@property (strong, nonatomic) uiview *boxview;
@property (nonatomic) bool isreading;
@property (strong, nonatomic) calayer *scanlayer;
-(bool)startreading;
-(void)stopreading;

//捕捉会话

@property (nonatomic, strong) avcapturesession *capturesession;

//展示layer

@property (nonatomic, strong) avcapturevideopreviewlayer *videopreviewlayer;

然后在viewdidload方法中初始化

- (void)viewdidload {
  [super viewdidload];

  _capturesession = nil;
   _isreading = no;
  
}

接下来实现startreading方法（这可就是重点咯）

- (bool)startreading {
 nserror *error;
 //1.初始化捕捉设备（avcapturedevice），类型为avmediatypevideo
 avcapturedevice *capturedevice = [avcapturedevice defaultdevicewithmediatype:avmediatypevideo];
 //2.用capturedevice创建输入流
 avcapturedeviceinput *input = [avcapturedeviceinput deviceinputwithdevice:capturedevice error:&error];
 if (!input) {
  nslog(@"%@", [error localizeddescription]);
  return no;
 }
 //3.创建媒体数据输出流
 avcapturemetadataoutput *capturemetadataoutput = [[avcapturemetadataoutput alloc] init];
 //4.实例化捕捉会话
 _capturesession = [[avcapturesession alloc] init];
 //4.1.将输入流添加到会话
 [_capturesession addinput:input];
 //4.2.将媒体输出流添加到会话中
 [_capturesession addoutput:capturemetadataoutput];
 //5.创建串行队列，并加媒体输出流添加到队列当中
 dispatch_queue_t dispatchqueue;
 dispatchqueue = dispatch_queue_create("myqueue", null);
 //5.1.设置代理
 [capturemetadataoutput setmetadataobjectsdelegate:self queue:dispatchqueue];
 //5.2.设置输出媒体数据类型为qrcode
 [capturemetadataoutput setmetadataobjecttypes:[nsarray arraywithobject:avmetadataobjecttypeqrcode]];
 //6.实例化预览图层
 _videopreviewlayer = [[avcapturevideopreviewlayer alloc] initwithsession:_capturesession];
 //7.设置预览图层填充方式
 [_videopreviewlayer setvideogravity:avlayervideogravityresizeaspectfill];
 //8.设置图层的frame
 [_videopreviewlayer setframe:_viewpreview.layer.bounds];
 //9.将图层添加到预览view的图层上
 [_viewpreview.layer addsublayer:_videopreviewlayer];
 //10.设置扫描范围
 capturemetadataoutput.rectofinterest = cgrectmake(0.2f, 0.2f, 0.8f, 0.8f);
 //10.1.扫描框
 _boxview = [[uiview alloc] initwithframe:cgrectmake(_viewpreview.bounds.size.width * 0.2f, _viewpreview.bounds.size.height * 0.2f, _viewpreview.bounds.size.width - _viewpreview.bounds.size.width * 0.4f, _viewpreview.bounds.size.height - _viewpreview.bounds.size.height * 0.4f)];
 _boxview.layer.bordercolor = [uicolor greencolor].cgcolor;
 _boxview.layer.borderwidth = 1.0f;
 [_viewpreview addsubview:_boxview];
 //10.2.扫描线
 _scanlayer = [[calayer alloc] init];
 _scanlayer.frame = cgrectmake(0, 0, _boxview.bounds.size.width, 1);
 _scanlayer.backgroundcolor = [uicolor browncolor].cgcolor;
 [_boxview.layer addsublayer:_scanlayer];
 nstimer *timer = [nstimer scheduledtimerwithtimeinterval:0.2f target:self selector:@selector(movescanlayer:) userinfo:nil repeats:yes];
 [timer fire];

 //10.开始扫描
 [_capturesession startrunning];
 return yes;
}

实现avcapturemetadataoutputobjectsdelegate协议方法

#pragma mark - avcapturemetadataoutputobjectsdelegate
- (void)captureoutput:(avcaptureoutput *)captureoutput didoutputmetadataobjects:(nsarray *)metadataobjects fromconnection:(avcaptureconnection *)connection
{
 //判断是否有数据
 if (metadataobjects != nil && [metadataobjects count] > 0) {
  avmetadatamachinereadablecodeobject *metadataobj = [metadataobjects objectatindex:0];
  //判断回传的数据类型
  if ([[metadataobj type] isequaltostring:avmetadataobjecttypeqrcode]) {
   [_lblstatus performselectoronmainthread:@selector(settext:) withobject:[metadataobj stringvalue] waituntildone:no];
   [self performselectoronmainthread:@selector(stopreading) withobject:nil waituntildone:no];
   _isreading = no;
  }
 }
}

实现计时器方法movescanlayer:(nstimer *)timer

- (void)movescanlayer:(nstimer *)timer
{
 cgrect frame = _scanlayer.frame;
 if (_boxview.frame.size.height < _scanlayer.frame.origin.y) {
  frame.origin.y = 0;
  _scanlayer.frame = frame;
 }else{
  frame.origin.y += 5;
  [uiview animatewithduration:0.1 animations:^{
   _scanlayer.frame = frame;
  }];
 }
}

实现开始和停止方法

- (ibaction)startstopreading:(id)sender {
  if (!_isreading) {
   if ([self startreading]) {
    [_startbtn settitle:@"stop" forstate:uicontrolstatenormal];
    [_lblstatus settext:@"scanning for qr code"];
   }
  }
  else{
   [self stopreading];
   [_startbtn settitle:@"start!" forstate:uicontrolstatenormal];
  }
  _isreading = !_isreading;
}
-(void)stopreading{
 [_capturesession stoprunning];
 _capturesession = nil;
 [_scanlayer removefromsuperlayer];
 [_videopreviewlayer removefromsuperlayer];
}

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