用系统自带的视听媒体的框架，AVFoundation实现照片拍摄。相比UIKit框架（UIImagePickerController高度封装），AVFoundation框架让开发者有更大的发挥空间。
首先看一下效果图：
下面贴上核心控制器代码：
#import "HWPhotoVC.h"#import <AVFoundation/AVFoundation.h>@interface HWPhotoVC ()@property (nonatomic, strong) AVCaptureSession *captureSession;//负责输入和输出设备之间的数据传递@property (nonatomic, strong) AVCaptureDeviceInput *captureDeviceInput;//负责从AVCaptureDevice获得输入数据@property (nonatomic, strong) AVCaptureStillImageOutput *captureStillImageOutput;//照片输出流@property (nonatomic, strong) AVCaptureVideoPreviewLayer *captureVideoPreviewLayer;//相机拍摄预览图层@property (nonatomic, weak) UIView *containerView;//内容视图@property (nonatomic, weak) UIImageView *focusCursor;//聚焦按钮@property (nonatomic, weak) UIImageView *imgView;//拍摄照片@end@implementation HWPhotoVC- (void)viewDidLoad { [super viewDidLoad]; self.navigationItem.title = @"拍照"; self.view.backgroundColor = [UIColor whiteColor]; //创建控件 [self creatControl];}- (void)viewWillAppear:(BOOL)animated{ [super viewWillAppear:animated]; //初始化信息 [self initPhotoInfo];}- (void)viewDidAppear:(BOOL)animated{ [super viewDidAppear:animated]; [self.captureSession startRunning];}- (void)viewDidDisappear:(BOOL)animated{ [super viewDidDisappear:animated]; [self.captureSession stopRunning];}- (void)creatControl{ CGFloat btnW = 150.f; CGFloat btnH = 40.f; CGFloat marginY = 20.f; CGFloat w = [UIScreen mainScreen].bounds.size.width; CGFloat h = [UIScreen mainScreen].bounds.size.height; //内容视图 CGFloat containerViewH = h - 64 - btnH - marginY * 3; UIView *containerView = [[UIView alloc] initWithFrame:CGRectMake(10, 64 + marginY, w - 20, containerViewH)]; containerView.backgroundColor = [UIColor whiteColor]; containerView.layer.borderWidth = 1.f; containerView.layer.borderColor = [[UIColor grayColor] CGColor]; [self.view addSubview:containerView]; _containerView = containerView; //摄像头切换按钮 CGFloat cameraSwitchBtnW = 50.f; CGFloat cameraSwitchBtnMargin = 10.f; UIButton *cameraSwitchBtn = [[UIButton alloc] initWithFrame:CGRectMake(containerView.bounds.size.width - cameraSwitchBtnW - cameraSwitchBtnMargin, 64 + marginY + cameraSwitchBtnMargin, cameraSwitchBtnW, cameraSwitchBtnW)]; [cameraSwitchBtn setImage:[UIImage imageNamed:@"camera_switch"] forState:UIControlStateNormal]; [cameraSwitchBtn addTarget:self action:@selector(cameraSwitchBtnOnClick) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:cameraSwitchBtn]; //聚焦图片 UIImageView *focusCursor = [[UIImageView alloc] initWithFrame:CGRectMake(50, 50, 75, 75)]; focusCursor.alpha = 0; focusCursor.image = [UIImage imageNamed:@"camera_focus_red"]; [containerView addSubview:focusCursor]; _focusCursor = focusCursor; //拍摄照片容器 UIImageView *imgView = [[UIImageView alloc] initWithFrame:containerView.frame]; imgView.hidden = YES; imgView.layer.borderWidth = 1.f; imgView.layer.borderColor = [[UIColor grayColor] CGColor]; imgView.contentMode = UIViewContentModeScaleAspectFill; imgView.clipsToBounds = YES; [self.view addSubview:imgView]; _imgView = imgView; //按钮 NSArray *titleArray = @[@"拍摄照片", @"重新拍摄"]; CGFloat btnY = CGRectGetMaxY(containerView.frame) + marginY; CGFloat margin = (w - btnW * titleArray.count) / (titleArray.count + 1); for (int i = 0; i < titleArray.count; i++) { CGFloat btnX = margin + (margin + btnW) * i; UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(btnX, btnY, btnW, btnH)]; btn.tag = 1000 + i; [btn setTitle:titleArray[i] forState:UIControlStateNormal]; btn.backgroundColor = [UIColor orangeColor]; btn.layer.cornerRadius = 2.0f; btn.layer.masksToBounds = YES; if (i == 1) { btn.hidden = YES; } [btn addTarget:self action:@selector(btnOnClick:) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:btn]; }}- (void)initPhotoInfo{ //初始化会话 _captureSession = [[AVCaptureSession alloc] init]; //设置分辨率 if ([_captureSession canSetSessionPreset:AVCaptureSessionPreset1280x720]) { _captureSession.sessionPreset = AVCaptureSessionPreset1280x720; } //获得输入设备,取得后置摄像头 AVCaptureDevice *captureDevice = [self getCameraDeviceWithPosition:AVCaptureDevicePositionBack]; if (!captureDevice) { NSLog(@"取得后置摄像头时出现问题"); return; } NSError *error = nil; //根据输入设备初始化设备输入对象，用于获得输入数据 _captureDeviceInput = [[AVCaptureDeviceInput alloc]initWithDevice:captureDevice error:&error]; if (error) { NSLog(@"取得设备输入对象时出错，错误原因：%@", error.localizedDescription); return; } //初始化设备输出对象，用于获得输出数据 _captureStillImageOutput = [[AVCaptureStillImageOutput alloc] init]; NSDictionary *outputSettings = @{AVVideoCodecKey:AVVideoCodecJPEG}; //输出设置 [_captureStillImageOutput setOutputSettings:outputSettings]; //将设备输入添加到会话中 if ([_captureSession canAddInput:_captureDeviceInput]) { [_captureSession addInput:_captureDeviceInput]; } //将设备输出添加到会话中 if ([_captureSession canAddOutput:_captureStillImageOutput]) { [_captureSession addOutput:_captureStillImageOutput]; } //创建视频预览层，用于实时展示摄像头状态 _captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession]; //摄像头方向 AVCaptureConnection *captureConnection = [self.captureVideoPreviewLayer connection]; captureConnection.videoOrientation = AVCaptureVideoOrientationPortrait; CALayer *layer = _containerView.layer; layer.masksToBounds = YES; _captureVideoPreviewLayer.frame = layer.bounds; //填充模式 _captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill; //将视频预览层添加到界面中 [layer insertSublayer:_captureVideoPreviewLayer below:self.focusCursor.layer]; [self addNotificationToCaptureDevice:captureDevice]; [self addGenstureRecognizer];}- (void)btnOnClick:(UIButton *)btn{ if (btn.tag == 1000) { //拍摄照片 [self photoBtnOnClick]; }else if (btn.tag == 1001) { //重新拍摄 [self resetPhoto]; }}#pragma mark 拍照- (void)photoBtnOnClick{ //根据设备输出获得连接 AVCaptureConnection *captureConnection = [self.captureStillImageOutput connectionWithMediaType:AVMediaTypeVideo]; captureConnection.videoOrientation = AVCaptureVideoOrientationPortrait; //根据连接取得设备输出的数据 [self.captureStillImageOutput captureStillImageAsynchronouslyFromConnection:captureConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) { if (imageDataSampleBuffer) { NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer]; UIImage *image = [UIImage imageWithData:imageData]; _imgView.image = image; _imgView.hidden = NO; } }]; UIButton *btn = (UIButton *)[self.view viewWithTag:1001]; btn.hidden = NO;}//重新拍摄- (void)resetPhoto{ _imgView.hidden = YES; UIButton *btn = (UIButton *)[self.view viewWithTag:1001]; btn.hidden = YES;}#pragma mark - 通知//给输入设备添加通知- (void)addNotificationToCaptureDevice:(AVCaptureDevice *)captureDevice{ //注意添加区域改变捕获通知必须首先设置设备允许捕获 [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) { captureDevice.subjectAreaChangeMonitoringEnabled = YES; }]; //捕获区域发生改变 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(areaChange:) name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice];}- (void)removeNotificationFromCaptureDevice:(AVCaptureDevice *)captureDevice{ [[NSNotificationCenter defaultCenter] removeObserver:self name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice];}//移除所有通知- (void)removeNotification{ [[NSNotificationCenter defaultCenter] removeObserver:self];}//设备连接成功- (void)deviceConnected:(NSNotification *)notification{ NSLog(@"设备已连接...");}//设备连接断开- (void)deviceDisconnected:(NSNotification *)notification{ NSLog(@"设备已断开.");}//捕获区域改变- (void)areaChange:(NSNotification *)notification{ NSLog(@"捕获区域改变...");}#pragma mark - 私有方法//取得指定位置的摄像头- (AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition )position{ NSArray *cameras = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; for (AVCaptureDevice *camera in cameras) { if ([camera position] == position) { return camera; } } return nil;}#pragma mark 切换前后摄像头- (void)cameraSwitchBtnOnClick{ AVCaptureDevice *currentDevice = [self.captureDeviceInput device]; AVCaptureDevicePosition currentPosition = [currentDevice position]; [self removeNotificationFromCaptureDevice:currentDevice]; AVCaptureDevice *toChangeDevice; AVCaptureDevicePosition toChangePosition = AVCaptureDevicePositionFront; if (currentPosition == AVCaptureDevicePositionUnspecified || currentPosition == AVCaptureDevicePositionFront) { toChangePosition = AVCaptureDevicePositionBack; } toChangeDevice = [self getCameraDeviceWithPosition:toChangePosition]; [self addNotificationToCaptureDevice:toChangeDevice]; //获得要调整的设备输入对象 AVCaptureDeviceInput *toChangeDeviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:toChangeDevice error:nil]; //改变会话的配置前一定要先开启配置，配置完成后提交配置改变 [self.captureSession beginConfiguration]; //移除原有输入对象 [self.captureSession removeInput:self.captureDeviceInput]; //添加新的输入对象 if ([self.captureSession canAddInput:toChangeDeviceInput]) { [self.captureSession addInput:toChangeDeviceInput]; self.captureDeviceInput = toChangeDeviceInput; } //提交会话配置 [self.captureSession commitConfiguration];}//改变设备属性的统一操作方法- (void)changeDeviceProperty:(void (^)(AVCaptureDevice *))propertyChange{ AVCaptureDevice *captureDevice = [self.captureDeviceInput device]; NSError *error; //注意改变设备属性前一定要首先调用lockForConfiguration:调用完之后使用unlockForConfiguration方法解锁 if ([captureDevice lockForConfiguration:&error]) { propertyChange(captureDevice); [captureDevice unlockForConfiguration]; }else { NSLog(@"设置设备属性过程发生错误，错误信息：%@", error.localizedDescription); }}//设置闪光灯模式- (void)setFlashMode:(AVCaptureFlashMode)flashMode{ [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) { if ([captureDevice isFlashModeSupported:flashMode]) { [captureDevice setFlashMode:flashMode]; } }];}//设置聚焦模式- (void)setFocusMode:(AVCaptureFocusMode)focusMode{ [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) { if ([captureDevice isFocusModeSupported:focusMode]) { [captureDevice setFocusMode:focusMode]; } }];}//设置曝光模式- (void)setExposureMode:(AVCaptureExposureMode)exposureMode{ [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) { if ([captureDevice isExposureModeSupported:exposureMode]) { [captureDevice setExposureMode:exposureMode]; } }];}//设置聚焦点- (void)focusWithMode:(AVCaptureFocusMode)focusMode exposureMode:(AVCaptureExposureMode)exposureMode atPoint:(CGPoint)point{ [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) { if ([captureDevice isFocusModeSupported:focusMode]) { [captureDevice setFocusMode:AVCaptureFocusModeAutoFocus]; } if ([captureDevice isFocusPointOfInterestSupported]) { [captureDevice setFocusPointOfInterest:point]; } if ([captureDevice isExposureModeSupported:exposureMode]) { [captureDevice setExposureMode:AVCaptureExposureModeAutoExpose]; } if ([captureDevice isExposurePointOfInterestSupported]) { [captureDevice setExposurePointOfInterest:point]; } }];}//添加点按手势，点按时聚焦- (void)addGenstureRecognizer{ [self.containerView addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapScreen:)]];}- (void)tapScreen:(UITapGestureRecognizer *)tapGesture{ CGPoint point = [tapGesture locationInView:self.containerView]; //将UI坐标转化为摄像头坐标 CGPoint cameraPoint = [self.captureVideoPreviewLayer captureDevicePointOfInterestForPoint:point]; [self setFocusCursorWithPoint:point]; [self focusWithMode:AVCaptureFocusModeAutoFocus exposureMode:AVCaptureExposureModeAutoExpose atPoint:cameraPoint];}//设置聚焦光标位置- (void)setFocusCursorWithPoint:(CGPoint)point{ self.focusCursor.center = point; self.focusCursor.transform = CGAffineTransformMakeScale(1.5, 1.5); self.focusCursor.alpha = 1.0; [UIView animateWithDuration:1.0 animations:^{ self.focusCursor.transform = CGAffineTransformIdentity; } completion:^(BOOL finished) { self.focusCursor.alpha = 0; }];}- (void)dealloc{ [self removeNotification];}@end
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