背景
由于项目中需要拍照功能，但是系统原生的相机功能根本满足不了项目的需要，所以就只能自定义一个相加了。苹果再AVFoundation框架中给我们提供了各个api，我们完全可以通过这些api自定义一个满足我们需求的相机。
关键类
AVCaptureSession 负责输入流和输出流的管理。
AVCaptureDeviceInput 输入流。连接输入采集设备的
AVCaptureStillImageOutput 输出流。AVCaptureOutput的子类，主要是负责采集图片数据的，不过这个类再10.0以后废弃掉了，改用AVCapturePhotoOutput这个替换，这个类能够支持RAW格式的图片
AVCaptureVideoPreviewLayer 集成CALayer，负责将采集的视频展示出来的一个类，提供了一个预览功能而已
实现过程
#import "TakePictureViewController.h"
#import <AVFoundation/AVFoundation.h>
#import "UIImage+Rotate.h"
#import "UIControl+Custom.h"
#define KSCREEN_WIDTH [[UIScreen mainScreen] bounds].size.width
#define KSCREEN_HEIGHT [[UIScreen mainScreen] bounds].size.height
typedef NS_ENUM(NSInteger, AVCamSetupResult ) {
AVCamSetupResultSuccess,
AVCamSetupResultCameraNotAuthorized,
AVCamSetupResultSessionConfigurationFailed
};
@interface TakePictureViewController ()
{
BOOL lightOn;
AVCaptureDevice *device;
ActivityIndicatorTipView *activityView;
}
// 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)AVCaptureSession *session;
// AVCaptureDeviceInput对象是输入流
@property (nonatomic, strong)AVCaptureDeviceInput *videoInput;
// 照片输出流对象
@property (nonatomic, strong)AVCaptureStillImageOutput *stillImageOutput;
// 预览图层，来显示照相机拍摄到的画面
@property (nonatomic, strong)AVCaptureVideoPreviewLayer *previewLayer;
// 切换前后镜头的按钮
@property (nonatomic, strong)UIButton *toggleButton;
// 放置预览图层的View
@property (nonatomic, strong)UIView *cameraShowView;
// 用来展示拍照获取的照片
@property (nonatomic, strong)UIImageView *imageShowView;
@property (nonatomic,strong) UIView *overlayView;
@property (nonatomic) dispatch_queue_t sessionQueue;
@property (nonatomic) AVCamSetupResult setupResult;
@end
@implementation TakePictureViewController
-(BOOL)prefersStatusBarHidden
{
return YES;
}
-(instancetype)init
{
self = [super init];
if (self)
{
[self initAll];
}
return self;
}
- (void)initAll{
[self initialSession];
[self initCameraShowView];
[self.view addSubview:self.overlayView];
[self initAVDevice];
[self setUpCameraLayer];
}
- (void)initialSession
{
self.session = [[AVCaptureSession alloc] init];
}
- (void)initCameraShowView
{
self.cameraShowView = [[UIView alloc] initWithFrame:self.view.frame];
[self.view addSubview:self.cameraShowView];
}
// 这是获取前后摄像头对象的方法
- (AVCaptureDevice *)cameraWithPosition:(AVCaptureDevicePosition)position
{
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *captureDevice in devices)
{
if (captureDevice.position == position)
{
return captureDevice;
}
}
return nil;
}
- (AVCaptureDevice *)frontCamera
{
return [self cameraWithPosition:AVCaptureDevicePositionFront];
}
- (AVCaptureDevice *)backCamera
{
return [self cameraWithPosition:AVCaptureDevicePositionBack];
}
/**
设备手电筒
*/
-(void)initAVDevice
{
device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if (![device hasTorch])
{
//无手电筒
[[[UIAlertView alloc] initWithTitle:@"tishi" message:@"无手电筒" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil] show];
}
lightOn = NO;
}
- (void)configureSession{
if ( self.setupResult != AVCamSetupResultSuccess ) {
return;
}
[self.session beginConfiguration];//保证对AVCaptureSession设置的原子性与commitConfiguration配对使用
self.videoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self backCamera] error:nil];
self.stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
// 输出流的设置参数AVVideoCodecJPEG参数表示以JPEG的图片格式输出图片
NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG,AVVideoCodecKey,@(0.1),AVVideoQualityKey,nil];
[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];
}
[self.session commitConfiguration];
}
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor whiteColor];
self.sessionQueue = dispatch_queue_create("session queue", DISPATCH_QUEUE_SERIAL);
switch ( [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo] )
{
case AVAuthorizationStatusAuthorized:
{
break;
}
case AVAuthorizationStatusNotDetermined:
{
dispatch_suspend( self.sessionQueue );
[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^( BOOL granted ) {
if ( ! granted ) {
self.setupResult = AVCamSetupResultCameraNotAuthorized;
}
dispatch_resume( self.sessionQueue );
}];
break;
}
default:
{
self.setupResult = AVCamSetupResultCameraNotAuthorized;
break;
}
}
dispatch_async(self.sessionQueue, ^{
[self configureSession];
});
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
dispatch_async( self.sessionQueue, ^{
switch ( self.setupResult )
{
case AVCamSetupResultSuccess:
{
[self.session startRunning];
break;
}
case AVCamSetupResultCameraNotAuthorized:
{
dispatch_async( dispatch_get_main_queue(), ^{
NSString *message = @"请允许拍照权限，以用来扫描二维码";
UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"提示" message:message preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleCancel handler:nil];
[alertController addAction:cancelAction];
UIAlertAction *settingsAction = [UIAlertAction actionWithTitle:@"设置" style:UIAlertActionStyleDefault handler:^( UIAlertAction *action ) {
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:UIApplicationOpenSettingsURLString] options:@{} completionHandler:nil];
}];
[alertController addAction:settingsAction];
[self presentViewController:alertController animated:YES completion:nil];
} );
break;
}
case AVCamSetupResultSessionConfigurationFailed:
{
dispatch_async( dispatch_get_main_queue(), ^{
NSString *message = @"没有拍照权限，所以不能扫描二维码";
UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"提示" message:message preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleCancel handler:nil];
[alertController addAction:cancelAction];
[self presentViewController:alertController animated:YES completion:nil];
} );
break;
}
}
} );
}
- (void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:animated];
dispatch_async( self.sessionQueue, ^{
if ( self.setupResult == AVCamSetupResultSuccess ) {
[self.session stopRunning];
}
} );
}
- (void)setUpCameraLayer
{
if (self.previewLayer == nil)
{
self.previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
UIView * view = self.cameraShowView;
CALayer * viewLayer = [view layer];
// UIView的clipsToBounds属性和CALayer的setMasksToBounds属性表达的意思是一致的,决定子视图的显示范围。当取值为YES的时候，剪裁超出父视图范围的子视图部分，当取值为NO时，不剪裁子视图。
[viewLayer setMasksToBounds:YES];
CGRect bounds = [view bounds];
[self.previewLayer setFrame:bounds];
[self.previewLayer setVideoGravity:AVLayerVideoGravityResizeAspect];
[viewLayer addSublayer:self.previewLayer];
}
}
/**
打开设备手电筒
*/
-(void) actionTurnOn
{
[device lockForConfiguration:nil];
[device setTorchMode:AVCaptureTorchModeOn];
[device unlockForConfiguration];
}
/**
关闭设备手电筒
*/
-(void) actionTurnOff
{
[device lockForConfiguration:nil];
[device setTorchMode: AVCaptureTorchModeOff];
[device unlockForConfiguration];
}
// 拍照
- (void)actionStartCamera
{
dispatch_async(self.sessionQueue, ^{
AVCaptureConnection *videoConnection = [self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo];
if (!videoConnection)
{
return;
}
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
if (imageDataSampleBuffer == NULL) {
return;
}
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
UIImage *originalImage = [UIImage imageWithData:imageData];
//1.旋转照片
UIImage *rotateImage = [originalImage rotate:UIImageOrientationRight];
});
}
@end
注意点
1、AVCaptureSession的配置过程和startRunning是阻挡主线程的一个耗时操作，所以我们放到另外的queue中操作，能够避免阻挡主线程
2、由于我们拍照不需要质量非常高的照片，所以我们通过setOutputSettings设置了图片质量，这样减少了很大一部分内存，可以根据情况来设置图片的质量。
3、拍完照片图片是倒立的，所以我们做了一个旋转操作，将图片正立了过来
