自iOS7以后，iOS扫描二维码就并不需要借助第三方的框架，这次项目的需求，自己实现一个扫描的功能，苹果在AVFoundation中原生支持扫描二维码的API，主要有5个类，这5个类在自定义相机或者视频时都用的上，这5个类分别是：
1.AVCaptureDevice:代表抽象的硬件设备
2.AVCaptureSession：会话对象，连接输入设备和输出设备。
3.AVCaptureDeviceInput：输入设备。设备输入数据管理对象，可以根据AVCaptureDevice创建对应的AVCaptureDeviceInput对象，该对象将会被添加到AVCaptureSession中管理
4.AVCaptureOutput：输出设备。输出设备管理对象，用于接收各类输出数据，有很多子类，每一个子类用途都不一样，该对象将会被添加到AVCaptureSession中管理
5.AVCaptureVideoPreviewLayer：相机拍摄预览图层，是CALayer的子类，使用该对象可以实时的查看拍照或视屏录制的效果，设置好尺寸后需要添加到父view的layer中
核心的步骤：
1.创建AVCaptureSession会话
2.创建AVCaptureDevice设备
3.创建输入AVCaptureDeviceInput与输出设备AVCaptureOutput，并添加到上面的绘画中
4.创建预览层
5.设置扫描区域
具体的代码如下：
#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
@interface ViewController ()<AVCaptureMetadataOutputObjectsDelegate,CALayerDelegate>
@property (weak, nonatomic) IBOutlet UIView *scanView;
@property (weak, nonatomic) IBOutlet UIImageView *scanline;
//结果
@property (weak, nonatomic) IBOutlet UILabel *result;
/**扫描区域的高度约束（高宽一致）*/
@property (weak, nonatomic) IBOutlet NSLayoutConstraint *scanViewH;
//扫描线顶部的约束
@property (weak, nonatomic) IBOutlet NSLayoutConstraint *scanlineTop;
@property (nonatomic,strong) CALayer *maskLayer;
/**
*五个类
*/
@property (nonatomic,strong)AVCaptureDevice *device;
@property (nonatomic,strong)AVCaptureDeviceInput *input;
@property (nonatomic,strong) AVCaptureMetadataOutput *output;
@property (nonatomic,strong) AVCaptureSession *session;
@property (nonatomic,strong) AVCaptureVideoPreviewLayer *layer;
@end
@implementation ViewController
#pragma mark - 懒加载
-(AVCaptureDevice *)device{
if (_device == nil) {
_device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
}
return _device;
}
-(AVCaptureDeviceInput *)input{
if (_input == nil) {
_input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];
}
return _input;
}
-(AVCaptureMetadataOutput *)output{
if (_output == nil) {
_output = [[AVCaptureMetadataOutput alloc]init];
[_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
}
return _output;
}
#pragma mark - ViewController生命周期
/**
* 扫描的那条线动起来
*/
-(void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
[UIView animateKeyframesWithDuration:3.0 delay:0 options:UIViewKeyframeAnimationOptionRepeat animations:^{
self.scanlineTop.constant = self.scanViewH.constant-4;
[self.view layoutIfNeeded];
} completion:^(BOOL finished) {
}];
}
//-(void)viewWillAppear:(BOOL)animated{
//
// [super viewWillAppear:animated];
//
// [UIView animateWithDuration:3.0 delay:0 options:UIViewAnimationOptionRepeat animations:^{
//
// self.scanlineTop.constant = self.scanViewH.constant - 4;
//
// [self.scanline layoutIfNeeded];
//
// } completion:nil];
//
//}
- (void)viewDidLoad {
[super viewDidLoad];
//1、创建会话
AVCaptureSession *session = [[AVCaptureSession alloc]init];
if ([session canSetSessionPreset:AVCaptureSessionPresetHigh]) {
[session setSessionPreset:AVCaptureSessionPresetHigh];
}
//2、添加输入和输出设备
if([session canAddInput:self.input]){
[session addInput:self.input];
}
if([session canAddOutput:self.output]){
[session addOutput:self.output];
}
//3、设置这次扫描的数据类型
self.output.metadataObjectTypes = self.output.availableMetadataObjectTypes;
//4、创建预览层
AVCaptureVideoPreviewLayer *layer = [AVCaptureVideoPreviewLayer layerWithSession:session];
layer.frame = self.view.bounds;
[self.view.layer insertSublayer:layer atIndex:0];
//5、创建周围的遮罩层
CALayer *maskLayer = [[CALayer alloc]init];
maskLayer.frame = self.view.bounds;
//此时设置的颜色就是中间扫描区域最终的颜色
maskLayer.backgroundColor = [UIColor colorWithRed:0.1 green:0.1 blue:0.1 alpha:0.2].CGColor;
maskLayer.delegate = self;
[self.view.layer insertSublayer:maskLayer above:layer];
//让代理方法调用 将周围的蒙版颜色加深
[maskLayer setNeedsDisplay];
//6、关键设置扫描的区域 方法一：自己计算
// CGFloat x = (self.view.bounds.size.width - self.scanViewH.constant) * 0.5;
//
// CGFloat y = (self.view.bounds.size.height- self.scanViewH.constant) * 0.5;
//
// CGFloat w = self.scanViewH.constant;
//
// CGFloat h = w;
//
//
// self.output.rectOfInterest = CGRectMake(y/self.view.bounds.size.height, x/self.view.bounds.size.width, h/self.view.bounds.size.height, w/self.view.bounds.size.width);
//6、关键设置扫描的区域，方法二：直接转换,但是要在 AVCaptureInputPortFormatDescriptionDidChangeNotification 通知里设置，否则 metadataOutputRectOfInterestForRect: 转换方法会返回 (0, 0, 0, 0)。
__weak __typeof(&*self)weakSelf = self;
[[NSNotificationCenter defaultCenter] addObserverForName:AVCaptureInputPortFormatDescriptionDidChangeNotification object:nil queue:[NSOperationQueue currentQueue] usingBlock: ^(NSNotification *_Nonnull note) {
weakSelf.output.rectOfInterest = [weakSelf.layer metadataOutputRectOfInterestForRect:self.scanView.frame];
}];
//7、开始扫描
[session startRunning];
self.session = session;
self.layer = layer;
self.maskLayer = maskLayer;
}
-(void)dealloc{
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
#pragma mark - 代理方法
/**
* 如果扫描到了二维码 回调该代理方法
*/
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
if(metadataObjects.count > 0 && metadataObjects != nil){
AVMetadataMachineReadableCodeObject *metadataObject = [metadataObjects lastObject];
NSString *result = metadataObject.stringValue;
self.result.text = result;
[self.session stopRunning];
[self.scanline removeFromSuperview];
}
}
/**
* 蒙版中间一块要空出来
*/
-(void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx{
if (layer == self.maskLayer) {
UIGraphicsBeginImageContextWithOptions(self.maskLayer.frame.size, NO, 1.0);
//蒙版新颜色
CGContextSetFillColorWithColor(ctx, [UIColor colorWithRed:0 green:0 blue:0 alpha:0.6].CGColor);
//补充当前填充颜色的rect
CGContextFillRect(ctx, self.maskLayer.frame);
//转换坐标
CGRect scanFrame = [self.view convertRect:self.scanView.frame fromView:self.scanView.superview];
//空出中间一块
CGContextClearRect(ctx, scanFrame);
}
}
@end
特别说明
在iOS10的权限问题，因为iOS10对权限的要求更高，如果我们不设置相应的权限问题，会直接导致程序崩溃，这时，我们需要在plist文件中加上相机权限的描述：
<key>NSCameraUsageDescription</key>
<string>cameraDesciption</string>
