关于ios:iOS使用视听媒体框架AVFoundation实现照片拍摄

用零碎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施展空间。

首先看一下效果图：
上面贴上外围控制器代码：

#import "HWPhotoVC.h"
#import <AVFoundation/AVFoundation.h>
 
@interface HWPhotoVC ()
 
@property (nonatomic, strong) AVCaptureSession *captureSession;// 负责输出和输出设备之间的数据传递
@property (nonatomic, strong) AVCaptureDeviceInput *captureDeviceInput;// 负责从 AVCaptureDevice 取得输出数据
@property (nonatomic, strong) AVCaptureStillImageOutput *captureStillImageOutput;// 照片输入流
@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];
 
 // 创立控件
 [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", @"从新拍摄"];
 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;}
 
 // 取得输出设施, 获得后置摄像头
 AVCaptureDevice *captureDevice = [self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];
 if (!captureDevice) {NSLog(@"获得后置摄像头时呈现问题");
  return;
 }
 
 NSError *error = nil;
 // 依据输出设施初始化设施输出对象，用于取得输出数据
 _captureDeviceInput = [[AVCaptureDeviceInput alloc]initWithDevice:captureDevice error:&error];
 if (error) {NSLog(@"获得设施输出对象时出错，谬误起因：%@", error.localizedDescription);
  return;
 }
 
 // 初始化设施输入对象，用于取得输入数据
 _captureStillImageOutput = [[AVCaptureStillImageOutput alloc] init];
 NSDictionary *outputSettings = @{AVVideoCodecKey:AVVideoCodecJPEG};
 // 输入设置
 [_captureStillImageOutput setOutputSettings:outputSettings];
 
 // 将设施输出增加到会话中
 if ([_captureSession canAddInput:_captureDeviceInput]) {[_captureSession addInput:_captureDeviceInput];
 }
 
 // 将设施输入增加到会话中
 if ([_captureSession canAddOutput:_captureStillImageOutput]) {[_captureSession addOutput:_captureStillImageOutput];
 }
 
 // 创立视频预览层，用于实时展现摄像头状态
 _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;
 // 将视频预览层增加到界面中
 [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) {
  // 从新拍摄
  [self resetPhoto];
 }
}
 
#pragma mark 拍照
- (void)photoBtnOnClick
{
 // 依据设施输入取得连贯
 AVCaptureConnection *captureConnection = [self.captureStillImageOutput connectionWithMediaType:AVMediaTypeVideo];
 captureConnection.videoOrientation = AVCaptureVideoOrientationPortrait;
 
 // 依据连贯获得设施输入的数据
 [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;
}
 
// 从新拍摄
- (void)resetPhoto
{
 _imgView.hidden = YES;
 UIButton *btn = (UIButton *)[self.view viewWithTag:1001];
 btn.hidden = YES;
}
 
#pragma mark - 告诉
// 给输出设施增加告诉
- (void)addNotificationToCaptureDevice:(AVCaptureDevice *)captureDevice
{
 // 留神增加区域扭转捕捉告诉必须首先设置设施容许捕捉
 [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {captureDevice.subjectAreaChangeMonitoringEnabled = YES;}];
 
 // 捕捉区域产生扭转
 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(areaChange:) name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice];
}
 
- (void)removeNotificationFromCaptureDevice:(AVCaptureDevice *)captureDevice
{[[NSNotificationCenter defaultCenter] removeObserver:self name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice];
}
 
// 移除所有告诉
- (void)removeNotification
{[[NSNotificationCenter defaultCenter] removeObserver:self];
}
 
// 设施连贯胜利
- (void)deviceConnected:(NSNotification *)notification
{NSLog(@"设施已连贯...");
}
 
// 设施连贯断开
- (void)deviceDisconnected:(NSNotification *)notification
{NSLog(@"设施已断开.");
}
 
// 捕捉区域扭转
- (void)areaChange:(NSNotification *)notification
{NSLog(@"捕捉区域扭转...");
}
 
#pragma mark - 公有办法
// 获得指定地位的摄像头
- (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];
 // 取得要调整的设施输出对象
 AVCaptureDeviceInput *toChangeDeviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:toChangeDevice error:nil];
 
 // 扭转会话的配置前肯定要先开启配置，配置实现后提交配置扭转
 [self.captureSession beginConfiguration];
 // 移除原有输出对象
 [self.captureSession removeInput:self.captureDeviceInput];
 // 增加新的输出对象
 if ([self.captureSession canAddInput:toChangeDeviceInput]) {[self.captureSession addInput:toChangeDeviceInput];
  self.captureDeviceInput = toChangeDeviceInput;
 }
 // 提交会话配置
 [self.captureSession commitConfiguration];
}
 
// 扭转设施属性的对立操作方法
- (void)changeDeviceProperty:(void (^)(AVCaptureDevice *))propertyChange
{AVCaptureDevice *captureDevice = [self.captureDeviceInput device];
 NSError *error;
 // 留神扭转设施属性前肯定要首先调用 lockForConfiguration: 调用完之后应用 unlockForConfiguration 办法解锁
 if ([captureDevice lockForConfiguration:&error]) {propertyChange(captureDevice);
  [captureDevice unlockForConfiguration];
 
 }else {NSLog(@"设置设施属性过程产生谬误，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];
  }
 }];
}
 
// 增加点按手势，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];
}
 
// 设置聚焦光标地位
- (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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