掃描二維碼效果

源碼：https://github.com/YouXianMing/Animations 

//
// QRCodeView.h
// QRCode
//
// Created by YouXianMing on 16/7/7.
// Copyright © 2016年 XianMing You. All rights reserved.
//

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
@class QRCodeView;

@protocol QRCodeViewDelegate <NSObject>

@optional

/**
 * 獲取QR的掃描結果
 *
 * @param codeView QRCodeView實體對象
 * @param codeString 掃描字符串
 */
- (void)QRCodeView:(QRCodeView *)codeView codeString:(NSString *)codeString;

@end

@interface QRCodeView : UIView

/**
 * 代理
 */
@property (nonatomic, weak) id <QRCodeViewDelegate> delegate;

/**
 * 燈的狀態,默認為關閉
 */
@property (nonatomic) AVCaptureTorchMode torchMode;

/**
 * 敏感區域,如果不設置,則為全部掃描區域
 */
@property (nonatomic) CGRect interestArea;

/**
 * 你用來添加自定義控件的view,尺寸與當前初始化的view一致
 */
@property (nonatomic, strong) UIView *contentView;

/**
 * 正在運行當中
 */
@property (nonatomic, readonly) BOOL isRunning;

/**
 * 開始掃描
 *
 * @return 如果成功,則返回YES,否則返回NO
 */
- (BOOL)start;

/**
 * 結束掃描
 */
- (void)stop;

@end

//
// QRCodeView.m
// QRCode
//
// Created by YouXianMing on 16/7/7.
// Copyright © 2016年 XianMing You. All rights reserved.
//

#import "QRCodeView.h"

@interface QRCodeView () <AVCaptureMetadataOutputObjectsDelegate>

@property (nonatomic) BOOL         isRunning;
@property (nonatomic, strong) UIView      *videoView;

@property (nonatomic, strong) AVCaptureDeviceInput  *deviceInput;
@property (nonatomic, strong) AVCaptureDevice    *captureDevice;
@property (nonatomic, strong) AVCaptureSession   *captureSession;
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *videoPreviewLayer;
@property (nonatomic, strong) AVCaptureMetadataOutput  *captureMetadataOutput;

@end

@implementation QRCodeView

- (instancetype)initWithFrame:(CGRect)frame {
 
 if (self = [super initWithFrame:frame]) {
  
  self.videoView = [[UIView alloc] initWithFrame:self.bounds];
  [self addSubview:self.videoView];
  
  self.contentView = [[UIView alloc] initWithFrame:self.bounds];
  [self addSubview:self.contentView];
  
  self.captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
  
  _torchMode = AVCaptureTorchModeOff;
  
  [self addNotificationCenter];
 }
 
 return self;
}

#pragma mark - NSNotificationCenter related.

- (void)addNotificationCenter {
 
 [[NSNotificationCenter defaultCenter] addObserver:self
            selector:@selector(notificationCenterEvent:)
             name:AVCaptureInputPortFormatDescriptionDidChangeNotification
            object:nil];
}

- (void)removeNotificationCenter {
 
 [[NSNotificationCenter defaultCenter] removeObserver:self
             name:AVCaptureInputPortFormatDescriptionDidChangeNotification
             object:nil];
}

- (void)notificationCenterEvent:(NSNotification *)sender {
 
 if (self.interestArea.size.width && self.interestArea.size.height) {
  
  self.captureMetadataOutput.rectOfInterest = [self.videoPreviewLayer metadataOutputRectOfInterestForRect:self.interestArea];
  
 } else {
  
  self.captureMetadataOutput.rectOfInterest = CGRectMake(0, 0, 1, 1);
 }
}

#pragma mark - Start & Stop.

- (BOOL)start {
 
 // 初始化輸入流
 BOOL  result = NO;
 NSError *error = nil;
 self.deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:self.captureDevice error:&error];
 if (self.deviceInput == nil) {
  
  NSLog(@"%@", error);
  return result;
 }
 
 // 創建會話
 self.captureSession = [[AVCaptureSession alloc] init];
 
 // 添加輸入流
 [self.captureSession addInput:self.deviceInput];
 
 // 初始化輸出流
 self.captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
 
 // 添加輸出流
 [self.captureSession addOutput:self.captureMetadataOutput];
 
 // 創建queue.
 [self.captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatch_queue_create(nil, nil)];
 self.captureMetadataOutput.metadataObjectTypes = @[AVMetadataObjectTypeQRCode];
 
 // 創建輸出對象
 self.videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
 self.videoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
 self.videoPreviewLayer.frame = self.contentView.bounds;
 [self.videoView.layer addSublayer:self.videoPreviewLayer];
 
 // 開始
 [self.captureSession startRunning];
 self.isRunning = YES;
 result   = YES;
 
 return result;
}

- (void)stop {
 
 [self.captureSession stopRunning];
 self.isRunning  = NO;
 self.captureSession = nil;
}

#pragma mark - AVCaptureMetadataOutputObjectsDelegate

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects
  fromConnection:(AVCaptureConnection *)connection {
 
 if (metadataObjects.count > 0) {
  
  AVMetadataMachineReadableCodeObject *metadata = metadataObjects.firstObject;
  NSString       *result = nil;
  
  if ([metadata.type isEqualToString:AVMetadataObjectTypeQRCode]) {
   
   result = metadata.stringValue;
   
   if (_delegate && [_delegate respondsToSelector:@selector(QRCodeView:codeString:)]) {
    
    [_delegate QRCodeView:self codeString:result];
   }
  }
 }
}

#pragma mark - Setter & Getter.

- (void)setTorchMode:(AVCaptureTorchMode)torchMode {

 _torchMode = torchMode;
 
 if (_deviceInput && [self.captureDevice hasTorch]) {
  
  [self.captureDevice lockForConfiguration:nil];
  [self.captureDevice setTorchMode:torchMode];
  [self.captureDevice unlockForConfiguration];
 }
}

#pragma mark - System method.

- (void)dealloc {
 
 [self stop];
 [self removeNotificationCenter];
}

@end

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