AVFoundation--AVCaptureSession

//
//  ViewController.m
//  AVFountionCamera
//
//  Created by ZhuYi on 16/5/3.
//  Copyright © 2016年 DDP. All rights reserved.
//

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
#import <AssetsLibrary/AssetsLibrary.h>

@interface ViewController (){
    //负责输入和输出设置之间的数据传递
    AVCaptureSession *captureSesstion;
    //负责从AVCaptureDevice获得输入数据
    AVCaptureDeviceInput *capturedeviceInput;
    //照片输出流
    AVCaptureStillImageOutput *captureStillImageOutput;
    //相机拍摄预览图层
    AVCaptureVideoPreviewLayer *captureVediopreviewLayer;
    //拍照按钮
    UIButton *takephotoButton;
    UIView *viewContainer;
}

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    viewContainer = [[UIView alloc] initWithFrame:CGRectMake(, , self.view.frame.size.width, self.view.frame.size.height - )];
    [self.view addSubview:viewContainer];
    takephotoButton = [UIButton buttonWithType:UIButtonTypeCustom];
    takephotoButton.backgroundColor = [UIColor orangeColor];
    [takephotoButton addTarget:self action:@selector(takePhoto) forControlEvents:UIControlEventTouchUpInside];
    takephotoButton.frame = CGRectMake(, self.view.frame.size.height - , self.view.frame.size.width, );
    [self.view addSubview:takephotoButton];
    //初始化会话
    captureSesstion = [[AVCaptureSession alloc] init];
    if ([captureSesstion canSetSessionPreset:AVCaptureSessionPreset1920x1080]) {
        captureSesstion.sessionPreset = AVCaptureSessionPreset1920x1080;
    }
    //获得输入设备
    AVCaptureDevice *captureDevice=[self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];//取得后置摄像头
    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};
    [captureStillImageOutput setOutputSettings:outputSettings];//输出设置

    //将设备输入添加到会话中
    if ([captureSesstion canAddInput:capturedeviceInput]) {
        [captureSesstion addInput:capturedeviceInput];
    }

    //将设备输出添加到会话中
    if ([captureSesstion canAddOutput:captureStillImageOutput]) {
        [captureSesstion addOutput:captureStillImageOutput];
    }

    //创建视频预览层，用于实时展示摄像头状态
    captureVediopreviewLayer=[[AVCaptureVideoPreviewLayer alloc]initWithSession:captureSesstion];

    CALayer *layer = viewContainer.layer;
    layer.masksToBounds=YES;

    captureVediopreviewLayer.frame=layer.bounds;
    captureVediopreviewLayer.videoGravity=AVLayerVideoGravityResizeAspectFill;//填充模式
    //将视频预览层添加到界面中
    [layer addSublayer:captureVediopreviewLayer];
    [captureSesstion startRunning];
}
-(AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition )position{
    NSArray *cameras= [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *camera in cameras) {
        if ([camera position]==position) {
            return camera;
        }
    }
    return nil;
}
- (void)takePhoto{
    //根据设备输出获得连接
    AVCaptureConnection *captureConnection=[captureStillImageOutput connectionWithMediaType:AVMediaTypeVideo];
    //根据连接取得设备输出的数据
    [captureStillImageOutput captureStillImageAsynchronouslyFromConnection:captureConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
        if (imageDataSampleBuffer) {
            NSData *imageData=[AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
            UIImage *image=[UIImage imageWithData:imageData];
            UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
        }

    }];
}
@end