iOS实现摄像头实时采集图像

#import <UIKit/UIKit.h>
#import <CoreVideo/CoreVideo.h>
#import <CoreMedia/CoreMedia.h>
#import <AVFoundation/AVFoundation.h>
 
NS_ASSUME_NONNULL_BEGIN
 
@interface YHCameraView : UIView <AVCaptureVideoDataOutputSampleBufferDelegate>
 
@property (nonatomic, weak) UIImageView *cameraImageView;
@property (strong, nonatomic) AVCaptureDevice* device;
@property (strong, nonatomic) AVCaptureSession* captureSession;
@property (strong, nonatomic) AVCaptureVideoPreviewLayer* previewLayer;
@property (strong, nonatomic) UIImage* cameraImage;
 
@end
 
NS_ASSUME_NONNULL_END

#import "YHCameraView.h"
 
@implementation YHCameraView
 
- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.backgroundColor = [UIColor lightGrayColor];
        [self createUI];
    }
    return self;
}
 
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code
}
*/
 
- (void)createUI {
    NSArray* devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for(AVCaptureDevice *device in devices)
    {
        if([device position] == AVCaptureDevicePositionFront) // 前置摄像头
            self.device = device;
    }
    
    AVCaptureDeviceInput* input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];
    AVCaptureVideoDataOutput* output = [[AVCaptureVideoDataOutput alloc] init];
    output.alwaysDiscardsLateVideoFrames = YES;
 
    dispatch_queue_t queue;
    queue = dispatch_queue_create("cameraQueue", NULL);
    [output setSampleBufferDelegate:self queue:queue];
 
    NSString* key = (NSString *) kCVPixelBufferPixelFormatTypeKey;
    NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
    NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];
    [output setVideoSettings:videoSettings];
 
    self.captureSession = [[AVCaptureSession alloc] init];
    [self.captureSession addInput:input];
    [self.captureSession addOutput:output];
    [self.captureSession setSessionPreset:AVCaptureSessionPresetPhoto];
 
    self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
    self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
 
    // CHECK FOR YOUR APP
    NSInteger screenWidth = self.frame.size.width;
    NSInteger screenHeitht = self.frame.size.height;
    self.previewLayer.frame = self.bounds;
    self.previewLayer.orientation = AVCaptureVideoOrientationPortrait;
    // CHECK FOR YOUR APP
 
//    [self.layer insertSublayer:self.previewLayer atIndex:0];   // Comment-out to hide preview layer
 
    [self.captureSession startRunning];
}
 
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CVPixelBufferLockBaseAddress(imageBuffer, 0);
    uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);
 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    CGImageRef newImage = CGBitmapContextCreateImage(newContext);
 
    CGContextRelease(newContext);
    CGColorSpaceRelease(colorSpace);
 
    self.cameraImage = [UIImage imageWithCGImage:newImage scale:1.0f orientation:UIImageOrientationLeftMirrored]; // UIImageOrientationDownMirrored
    self.cameraImageView.image = [UIImage imageWithCGImage:newImage scale:1.0f orientation:UIImageOrientationLeftMirrored];
 
    CGImageRelease(newImage);
 
    CVPixelBufferUnlockBaseAddress(imageBuffer, 0);
}
 
@end

#pragma mark - 快照采集
/// 快照采集
- (YHCameraView *)cameraView {
    if (!_cameraView) {
        YHCameraView *view = [[YHCameraView alloc] init];
        view.frame = CGRectMake(1, 1, 1, 1);
        view.cameraImageView.image = view.cameraImage;
        _cameraView = view;
    }
    return _cameraView;
}
 
NSString *strImg = [YHCameraManager imageBase64EncodedWithImage:self.cameraView.cameraImage
                                                       AndImageType:@"JPEG"]; // 获取照片信息

/**
 图片转 Base64
 
 @param img     原图片
 @param type    图片类型(PNG 或 JPEG)
 @return        处理结果
 */
+ (NSString *)imageBase64EncodedWithImage:(UIImage *)img AndImageType:(NSString *)type {
    NSString *callBack = nil;
    if ([img isKindOfClass:[UIImage class]]) {
        NSData *data = [NSData data];
        if ([type isEqualToString:@"PNG"]) {
            data = UIImagePNGRepresentation(img);
        } else {
            data = UIImageJPEGRepresentation(img, 1.0f);
        }
        
        NSString *encodedImgStr = [data base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
        
        NSLog(@"YHCameraManager\nencodedImgStr: %@", encodedImgStr);
        return encodedImgStr;
    } else {
        return callBack;
    }
}