iOS-使用AVCaptureSession自定义相机(AVFondation)

关于iOS调用摄像机来获取照片，通常我们都会调用UIImagePickerController来调用系统提供的相机来拍照，这个控件非常好用。但是有时UIImagePickerController控件无法满足我们的需求，例如我们需要更加复杂的OverlayerView，这时候我们就要自己构造一个摄像机控件了。

并且个人发现使用系统的UIImagePickerController会发生内存泄漏，但是依然会走dealloc方法，所以无奈之下自己创建一个摄像头。

首先先介绍下自定义摄像头需要用到的几个系统类

//AVCaptureSession对象来执行输入设备和输出设备之间的数据传递
@property (strong, nonatomic) AVCaptureSession *session;//照片输出流对象
@property (strong, nonatomic) AVCaptureStillImageOutput *captureOutput;// 代表了输入设备,例如摄像头与麦克风。
@property (strong, nonatomic) AVCaptureDevice *device;//AVCaptureDeviceInput对象是输入流(摄像头或者麦克风),一个设备可能可以同时提供视频和音频的捕捉。我们可以分别用AVCaptureDeviceInput来代表视频输入和音频输入
@property (strong,nonatomic)AVCaptureDeviceInput * input;//预览图层，来显示照相机拍摄到的画面
@property (strong,nonatomic)AVCaptureVideoPreviewLayer * preview;

看图

一个显示用的AVCaptureVideoPreviewLayer，一个设备AVCaptureDevice，设备的输入流AVCaptureDeviceInput，设备的输出流AVCaptureStillImageOutput（这个仅限于输出成图片）需要用到中间层AVCaptureSession把图像给AVCaptureVideoPreviewLayer显示在view上。基本大致就是这个原理。

上代码：

- (void) initialize
{//1.创建会话层self.device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];// Inputself.input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];// Outputself.captureOutput = [[AVCaptureStillImageOutput alloc] init];NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG,AVVideoCodecKey,nil];[self.captureOutput setOutputSettings:outputSettings];// Sessionself.session = [[AVCaptureSession alloc]init];//AVCaptureSessionPresetHigh:实现高质量的视频和音频输出[self.session setSessionPreset:AVCaptureSessionPresetHigh];// addInput:可称为虽然会话正在运行if ([self.session canAddInput:self.input]){[self.session addInput:self.input];}if ([self.session canAddOutput:_captureOutput]){[self.session addOutput:_captureOutput];}self.preview =[AVCaptureVideoPreviewLayer layerWithSession:self.session];self.preview.videoGravity = AVLayerVideoGravityResizeAspectFill;self.preview.frame = self.view.bounds;[self.view.layer insertSublayer:self.preview atIndex:0];
}

重要的是做完需要启动

    if (self.session) {[self.session startRunning];}

当然如果你想在摄像机页面随意设置什么样的图形，自己再创建一个自定义view，自己布局即可。

拍照代码

-(void)Captureimage
{//get connectionAVCaptureConnection *videoConnection = nil;for (AVCaptureConnection *connection in self.captureOutput.connections) {for (AVCaptureInputPort *port in [connection inputPorts]) {if ([[port mediaType] isEqual:AVMediaTypeVideo] ) {videoConnection = connection;break;}}if (videoConnection) { break; }}//get UIImage__weak typeof(self) weakSelf = self;[self.captureOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error) {CFDictionaryRef exifAttachments =CMGetAttachment(imageSampleBuffer, kCGImagePropertyExifDictionary, NULL);if (exifAttachments) {// Do something with the attachments.}// Continue as appropriate.NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];UIImage *t_image = [UIImage imageWithData:imageData];t_image = [t_image fixOrientation];
//         CGRect cutterFrame = [self.codeIdentifierCarView imageViewFrame];CGRect cutterFrame = [_codeIdentifierCar imageViewFrame];UIImage *cutterImage = [t_image intoCutterVCWithInfoWithFrame:cutterFrame];cutterImage = cutterImage;weakSelf.cutterView.hidden = NO;[weakSelf.cutterView setBackImagViewWithImage:cutterImage];[weakSelf.view addSubview:self.cutterView];}];
}

需要反面拍照的：

// 反面拍照
- (void)changeCameraDevice
{// 翻转[UIView beginAnimations:@"animation" context:nil];[UIView setAnimationDuration:.5f];[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];[UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.view cache:YES];[UIView commitAnimations];NSArray *inputs = self.session.inputs;for ( AVCaptureDeviceInput *input in inputs ) {AVCaptureDevice *device = input.device;if ( [device hasMediaType:AVMediaTypeVideo] ) {AVCaptureDevicePosition position = device.position;AVCaptureDevice *newCamera = nil;AVCaptureDeviceInput *newInput = nil;if (position == AVCaptureDevicePositionFront)newCamera = [self cameraWithPosition:AVCaptureDevicePositionBack];elsenewCamera = [self cameraWithPosition:AVCaptureDevicePositionFront];newInput = [AVCaptureDeviceInput deviceInputWithDevice:newCamera error:nil];[self.session beginConfiguration];[self.session removeInput:input];[self.session addInput:newInput];// Changes take effect once the outermost commitConfiguration is invoked.[self.session commitConfiguration];break;}}
}

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