iOS使用AVCaptureSession自定义相机
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。
这需要使用AVFoundation.framework这个framework里面的组件了，所以我们先要导入这个头文件，另外还需要的组件官方文档是这么说的：
● An instance of AVCaptureDevice to represent the input device, such as a camera or microphone
● An instance of a concrete subclass of AVCaptureInput to configure the ports from the input device
● An instance of a concrete subclass of AVCaptureOutput to manage the output to a movie file or still image
● An instance of AVCaptureSession to coordinate the data flow from the input to the output
这里我只构造了一个具有拍照功能的照相机，至于录影和录音功能这里就不加说明了。
总结下来，我们需要以下的对象：
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@property (nonatomic, strong) AVCaptureSession * session;//AVCaptureSession对象来执行输入设备和输出设备之间的数据传递@property (nonatomic, strong) AVCaptureDeviceInput * videoInput;//AVCaptureDeviceInput对象是输入流@property (nonatomic, strong) AVCaptureStillImageOutput * stillImageOutput;//照片输出流对象，当然我的照相机只有拍照功能，所以只需要这个对象就够了@property (nonatomic, strong) AVCaptureVideoPreviewLayer * previewLayer;//预览图层，来显示照相机拍摄到的画面@property (nonatomic, strong) UIBarButtonItem * toggleButton;//切换前后镜头的按钮@property (nonatomic, strong) UIButton * shutterButton;//拍照按钮@property (nonatomic, strong) UIView * cameraShowView;//放置预览图层的View |
我的习惯是在init方法执行的时候创建这些对象，然后在viewWillAppear方法里加载预览图层。现在就让我们看一下代码就清楚了。
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- (void) initialSession{ //这个方法的执行我放在init方法里了 self.session = [[AVCaptureSession alloc] init]; self.videoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self frontCamera] error:nil]; //[self fronCamera]方法会返回一个AVCaptureDevice对象，因为我初始化时是采用前摄像头，所以这么写，具体的实现方法后面会介绍 self.stillImageOutput = [[AVCaptureStillImageOutput alloc] init]; NSDictionary * outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG,AVVideoCodecKey, nil]; //这是输出流的设置参数AVVideoCodecJPEG参数表示以JPEG的图片格式输出图片 [self.stillImageOutput setOutputSettings:outputSettings]; if ([self.session canAddInput:self.videoInput]) { [self.session addInput:self.videoInput]; } if ([self.session canAddOutput:self.stillImageOutput]) { [self.session addOutput:self.stillImageOutput]; } } |
这是获取前后摄像头对象的方法
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- (AVCaptureDevice *)cameraWithPosition:(AVCaptureDevicePosition) position { NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; for (AVCaptureDevice *device in devices) { if ([device position] == position) { return device; } } return nil;}- (AVCaptureDevice *)frontCamera { return [self cameraWithPosition:AVCaptureDevicePositionFront];}- (AVCaptureDevice *)backCamera { return [self cameraWithPosition:AVCaptureDevicePositionBack];} |
接下来在viewWillAppear方法里执行加载预览图层的方法
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- (void) setUpCameraLayer{ if (_cameraAvaible == NO) return; if (self.previewLayer == nil) { self.previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session]; UIView * view = self.cameraShowView; CALayer * viewLayer = [view layer]; [viewLayer setMasksToBounds:YES]; CGRect bounds = [view bounds]; [self.previewLayer setFrame:bounds]; [self.previewLayer setVideoGravity:AVLayerVideoGravityResizeAspect]; [viewLayer insertSublayer:self.previewLayer below:[[viewLayer sublayers] objectAtIndex:0]]; }} |
注意以下的方法，在viewDidAppear和viewDidDisappear方法中启动和关闭session
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- (void) viewDidAppear:(BOOL)animated{ [super viewDidAppear:animated]; if (self.session) { [self.session startRunning]; }}- (void) viewDidDisappear:(BOOL)animated{ [super viewDidDisappear: animated]; if (self.session) { [self.session stopRunning]; }} |
接着我们就来实现切换前后镜头的按钮，按钮的创建我就不多说了
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- (void)toggleCamera { NSUInteger cameraCount = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] count]; if (cameraCount > 1) { NSError *error; AVCaptureDeviceInput *newVideoInput; AVCaptureDevicePosition position = [[_videoInput device] position]; if (position == AVCaptureDevicePositionBack) newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self frontCamera] error:&error]; else if (position == AVCaptureDevicePositionFront) newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self backCamera] error:&error]; else return; if (newVideoInput != nil) { [self.session beginConfiguration]; [self.session removeInput:self.videoInput]; if ([self.session canAddInput:newVideoInput]) { [self.session addInput:newVideoInput]; [self setVideoInput:newVideoInput]; } else { [self.session addInput:self.videoInput]; } [self.session commitConfiguration]; } else if (error) { NSLog(@"toggle carema failed, error = %@", error); } }} |
这是切换镜头的按钮方法
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- (void) shutterCamera{ AVCaptureConnection * videoConnection = [self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo]; if (!videoConnection) { NSLog(@"take photo failed!"); return; } [self.stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) { if (imageDataSampleBuffer == NULL) { return; } NSData * imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer]; UIImage * image = [UIImage imageWithData:imageData]; NSLog(@"image size = %@",NSStringFromCGSize(image.size)); }];} |
这是拍照按钮的方法
这样自定义照相机的简单功能就完成了，如果你想要再添加其他复杂的功能，可以参考一下下面这篇文章，希望对你们有所帮助。
http://course.gdou.com/blog/Blog.pzs/archive/2011/12/14/10882.html
