iOS 使用AVFoundation 扫描二维码并限定扫描区域(带代码生成蒙版)

使用AVFoundation 生成的二维码扫描器，扫描速度快，加上扫描限定区域缩小扫描范围，另外代码直接在扫描区域外生成黑色透明蒙版，简单扫描动画。相册相片识别二维码信息（只支持ios8及以上版本）。功能写的比较简单，细节需要的自己去优化吧~详情见附件！

另外：二维码生成可以参考站内其他源码：http://blog.yourtion.com/custom-cifilter-qrcode-generator.html

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface QRCodeScanController : UIViewController<AVCaptureMetadataOutputObjectsDelegate>

@end

//NOTE: 二维码扫描实现。  生成二维码以及扫描二维码实现方式是基于AVFoundation库，由于Apple 在 IOS8.0后才
//      提供了从相册识别二维码的新特性（代码中已被注释掉），为了兼容IOS8.0以前机型，故识别相片二维码信息采用的是开源库ZXINGObjc.
//      ZBar  Zxing均已停止更新且不支持64位架构。

#import "QRCodeScanController.h"
#import "NSObject+GCD.h"

@interface QRCodeScanController ()

@property (weak, nonatomic) IBOutlet UIImageView *scanBackgrondImageView;

@property (weak, nonatomic) IBOutlet UIView *scanContainerView;

@property (weak, nonatomic) IBOutlet UIView *scanView;

@property (weak, nonatomic) IBOutlet UILabel *statusLabel;

@property(strong,nonatomic) AVCaptureSession *session; // 二维码生成的绘画

@property(strong,nonatomic)  AVCaptureVideoPreviewLayer *previewLayer;

@property(assign,nonatomic) BOOL finished;

@property (nonatomic,strong)UIImageView * readLineView;

//扫描器灰色蒙板。
@property (nonatomic,strong)CALayer * maskLayer;

@property(nonatomic,strong)CIDetector * detector;

@property(nonatomic,assign)CMVideoDimensions dimensions;

@property (nonatomic,strong) NSString * albumId;
@property (weak, nonatomic) IBOutlet UILabel *remindLabel;

@end

@implementation QRCodeScanController

- (void)dealloc{

// 删除预览图层
if (self.previewLayer) {
[self.previewLayer removeFromSuperlayer];
}
if (self.maskLayer) {
self.maskLayer.delegate = nil;
}
NSLog(@"%@ will dealloc !",NSStringFromClass([self class]));
}

- (void)viewDidLoad {
[super viewDidLoad];

self.navigationController.navigationBar.translucent = NO;
}

- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
[self stopScanning:self.session];
}

-(void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
if (!self.session) {
[self readQRcode];
}
}

- (void)onCancelBarButtonTouched:(id)sender{
[self dismissViewControllerAnimated:YES completion:nil];
}

//ios8.0及以上版本可使用。
- (CIDetector *)detector{
if (_detector == nil) {
NSDictionary * options = @{CIDetectorAccuracy : CIDetectorAccuracyHigh};
_detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:options];
}
return _detector;
}

- (void)doneButtonTouched:(id)sender{
if (self.finished) {
// 1. 如果扫描完成，停止会话

[self stopScanning:self.session];

// 2. 删除预览图层

[self.previewLayer removeFromSuperlayer];
}

[self dismissViewControllerAnimated:YES completion:^{

}];
}

- (void)setStatusText:(NSString *)text{

CGRect stringRect = [text boundingRectWithSize:CGSizeMake(self.statusLabel.frame.size.width, 80.0)
options:(NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading)
attributes:@{ NSFontAttributeName : self.statusLabel.font }
context:nil];
CGRect rect = self.statusLabel.frame;
rect.size.height = MAX(stringRect.size.height, rect.size.height);
self.statusLabel.frame = rect;
self.statusLabel.text = text;
}

//停止扫描
- (void)stopScanning:(AVCaptureSession *)session{

[session stopRunning];
safe_dispatch_main_async(^{
[self.scanBackgrondImageView.layer removeAllAnimations];
});
}

//开始扫描
- (void)startScanning:(AVCaptureSession *)session{
[session startRunning];
safe_dispatch_main_async(^{
if (_readLineView) {
[self.scanBackgrondImageView.layer removeAllAnimations];
}else{
[self loopDrawLine];
}
});
}

#pragma mark 扫描动画
-(void)loopDrawLine{

CGRect screenBounds = [[UIScreen mainScreen] bounds];
CGFloat scaleX = screenBounds.size.width/320.0;
CGFloat loopLineWidth = 244.0 * scaleX;

CGRect rect = CGRectMake(0, 5, loopLineWidth, 2);
if (_readLineView) {
[_readLineView removeFromSuperview];
}
__weak QRCodeScanController *weakSelf = self;
weakSelf.readLineView = [[UIImageView alloc] initWithFrame:rect];
[_readLineView setImage:[UIImage imageNamed:@"scan_line.png"]];
[UIView animateWithDuration:1.5
delay: 0.0
options: UIViewAnimationOptionCurveEaseIn
animations:^{
//修改fream的代码写在这里
weakSelf.readLineView.frame =CGRectMake(weakSelf.scanBackgrondImageView.frame.origin.x, weakSelf.scanBackgrondImageView.frame.origin.y+weakSelf.scanBackgrondImageView.frame.size.height - 5, loopLineWidth, 2);
[weakSelf.readLineView setAnimationRepeatCount:0];

}
completion:^(BOOL finished){
[weakSelf loopDrawLine];
}];

[weakSelf.scanBackgrondImageView addSubview:weakSelf.readLineView];
}

#pragma mark - 读取二维码

- (void)readQRcode{

// 1. 摄像头设备

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

// 2. 设置输入

// 因为模拟器是没有摄像头的，因此在此最好做一个判断

NSError *error = nil;

AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];

if (error) {

NSLog(@"没有摄像头-%@", error.localizedDescription);

return;
}

// 3. 设置输出(Metadata元数据)

AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];

// 3.1 设置输出的代理

// 说明：使用主线程队列，相应比较同步，使用其他队列，相应不同步，容易让用户产生不好的体验

[output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];

// 4. 拍摄会话

//在生成拍摄回话时原来直接设置的是最高清画质，但对于ipod 5这类低配设备是不支持的，故在此我采取了下面这种方式来设置画质。
AVCaptureSession *session = [[AVCaptureSession alloc] init];
if ([device supportsAVCaptureSessionPreset:AVCaptureSessionPreset1920x1080]) {
session.sessionPreset = AVCaptureSessionPreset1920x1080;//设置图像输出质量
self.dimensions = (CMVideoDimensions){1080,1920};
}else if ([device supportsAVCaptureSessionPreset:AVCaptureSessionPreset1280x720]){
session.sessionPreset = AVCaptureSessionPreset1280x720;
self.dimensions = (CMVideoDimensions){720,1280};
}else if ([device supportsAVCaptureSessionPreset:AVCaptureSessionPreset640x480]){
session.sessionPreset = AVCaptureSessionPreset640x480;
self.dimensions = (CMVideoDimensions){480,640};
}else if ([device supportsAVCaptureSessionPreset:AVCaptureSessionPreset352x288]){
session.sessionPreset = AVCaptureSessionPreset352x288;
self.dimensions = (CMVideoDimensions){288,352};
}

// 添加session的输入和输出

[session addInput:input];

[session addOutput:output];

// 4.1 设置输出的格式

// 提示：一定要先设置会话的输出为output之后，再指定输出的元数据类型！

[output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];

CGRect scanBounds = [self.view bounds];

// 5. 设置预览图层（用来让用户能够看到扫描情况）

AVCaptureVideoPreviewLayer *preview = [AVCaptureVideoPreviewLayer layerWithSession:session];

// 5.1 设置preview图层的属性

[preview setVideoGravity:AVLayerVideoGravityResizeAspectFill];

// 5.2 设置preview图层的大小

[preview setFrame:scanBounds];

preview.backgroundColor = [UIColor lightGrayColor].CGColor;

// 5.3 将图层添加到视图的图层

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

self.previewLayer = preview;

self.maskLayer = [[CALayer alloc]init];
self.maskLayer.frame = self.view.layer.bounds;
self.maskLayer.delegate = self;
[self.view.layer insertSublayer:self.maskLayer above:self.previewLayer];
[self.maskLayer setNeedsDisplay];

//5.4设置扫描区域

/*获取图像输出大小*/
CMVideoDimensions dimensions = self.dimensions;
CGFloat width = dimensions.width;
CGFloat height = dimensions.height;

CGSize size = scanBounds.size;

CGRect screenBounds = [[UIScreen mainScreen] bounds];
CGFloat scaleX = screenBounds.size.width/320.0;
CGFloat scaleY = screenBounds.size.height/568.0;
CGRect scanFrame = [self.view convertRect:self.scanView.frame fromView:self.scanView.superview];
CGRect cropRect = CGRectMake(scanFrame.origin.x * scaleX, scanFrame.origin.y * scaleY, scanFrame.size.width*scaleX, scanFrame.size.height * scaleY);

CGFloat p1 = size.height/size.width;
CGFloat p2 = height/width; //与之前设置的图像输出质量应该对应。
if (p1 < p2) {
CGFloat fixHeight = self.view.bounds.size.width * height / width; //缩放并剪裁后的高度。
CGFloat fixPadding = (fixHeight - size.height)/2;
output.rectOfInterest = CGRectMake((cropRect.origin.y + fixPadding)/fixHeight,
cropRect.origin.x/size.width,
cropRect.size.height/fixHeight,
cropRect.size.width/size.width);
} else {
CGFloat fixWidth = self.view.bounds.size.height * width / height;
CGFloat fixPadding = (fixWidth - size.width)/2;
output.rectOfInterest = CGRectMake(cropRect.origin.y/size.height,
(cropRect.origin.x + fixPadding)/fixWidth,
cropRect.size.height/size.height,
cropRect.size.width/fixWidth);
}
//说明: rectOfInterest 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
//      参数里的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,宽度和高度设置的情况也是类似
//      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  output.rectOfInterest=CGRectMake(0.5,0,0.5, 1)

// 6. 启动会话

[self startScanning:session];

self.session = session;

}

#pragma mark - 输出代理方法

// 此方法是在识别到QRCode，并且完成转换

// 如果QRCode的内容越大，转换需要的时间就越长

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

// 扫描结果

if (metadataObjects.count > 0) {

AVMetadataMachineReadableCodeObject *obj = metadataObjects[0];
NSString *result = obj.stringValue;

self.remindLabel.text = [NSString stringWithFormat:@"扫描结果:%@",result];
//result 即为扫描得到的结果。
//可以开始对扫描得到的结果进行相应处理了。
}
}

//Note: 蒙板生成。需设置代理，并在退出页面时取消代理。
-(void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx{
if (layer == self.maskLayer) {
UIGraphicsBeginImageContextWithOptions(self.maskLayer.frame.size, NO, 1.0);
CGContextSetFillColorWithColor(ctx, [UIColor colorWithRed:0 green:0 blue:0 alpha:0.6].CGColor);
CGContextFillRect(ctx, self.maskLayer.frame);
CGRect scanFrame = [self.view convertRect:self.scanView.frame fromView:self.scanView.superview];
CGContextClearRect(ctx, scanFrame);
}
}

@end