【IOS开发】实时显示摄像头内容

转自互联网：http://blog.csdn.net/dean19900504/article/details/8101522，有做修改。

ViewController：

#import 
#import 
@interface ViewController : UIViewController


@end

#import "ViewController.h"
#import "EnvConstant.h"

#import 
#import 
#import 

@interface ViewController ()

@end

@implementation ViewController{
    AVCaptureSession *_captureSession;
    UIImageView *_outputImageView;
    AVCaptureVideoPreviewLayer *_captureLayer;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    AVCaptureDeviceInput *captureInput = [AVCaptureDeviceInput deviceInputWithDevice:[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] error:nil];
    AVCaptureVideoDataOutput *captureOutput = [[AVCaptureVideoDataOutput alloc]init];
    captureOutput.alwaysDiscardsLateVideoFrames = YES;
    //captureOutput.minFrameDuration = CMTimeMake(1, 10);
    
    dispatch_queue_t queue;
    queue = dispatch_queue_create("cameraQueue", NULL);
    [captureOutput setSampleBufferDelegate:self queue:queue];
    NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;
    NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
    NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];
    [captureOutput setVideoSettings:videoSettings];
    _captureSession = [[AVCaptureSession alloc] init];
    [_captureSession addInput:captureInput];
    [_captureSession addOutput:captureOutput];
    [_captureSession startRunning];
    
    //实时显示摄像头内容
    _captureLayer = [AVCaptureVideoPreviewLayer layerWithSession: _captureSession];
    _captureLayer.frame = CGRectMake(10, START_POSITION+10, WIDTH-20, 200);
    _captureLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    [self.view.layer addSublayer: _captureLayer];
    
    //显示输出图片
    _outputImageView = [[UIImageView alloc]initWithFrame:CGRectMake(10, CGRectGetMaxY(_captureLayer.frame)+10, CGRectGetWidth(_captureLayer.frame), CGRectGetHeight(_captureLayer.frame))];
    [self.view addSubview:_outputImageView];
    
    
    UIButton *stopButton = [[UIButton alloc]initWithFrame:CGRectMake(10, CGRectGetMaxY(_outputImageView.frame)+30, CGRectGetWidth(_outputImageView.frame)/2-10, 50)];
    stopButton.backgroundColor = [UIColor blackColor];
    [stopButton setTitle:@"stop" forState:UIControlStateNormal];
    [stopButton setTitle:@"stop" forState:UIControlStateHighlighted];
    [stopButton addTarget:self action:@selector(stop) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:stopButton];
    
    UIButton *startButton = [[UIButton alloc]initWithFrame:CGRectMake(10+CGRectGetWidth(_outputImageView.frame)/2, CGRectGetMaxY(_outputImageView.frame)+30, CGRectGetWidth(_outputImageView.frame)/2-10, 50)];
    startButton.backgroundColor = [UIColor blackColor];
    [startButton setTitle:@"start" forState:UIControlStateNormal];
    [startButton setTitle:@"start" forState:UIControlStateHighlighted];
    [startButton addTarget:self action:@selector(start) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:startButton];
}

#pragma mark AVCaptureSession delegate
- (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);
    
    UIImage *image= [UIImage imageWithCGImage:newImage scale:1.0 orientation:UIImageOrientationRight];
    CGImageRelease(newImage);
    [_outputImageView performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:YES];
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
}

-(void)stop{
    [_captureSession stopRunning];
}
-(void)start{
    [_captureSession startRunning];
}

@end

-(UIImage *)imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer {
    CVImageBufferRef imageBuffer =  CMSampleBufferGetImageBuffer(sampleBuffer);
    CIImage *ciImage = [CIImage imageWithCVPixelBuffer:imageBuffer];
    CIContext *temporaryContext = [CIContext contextWithOptions:nil];
    CGImageRef videoImage = [temporaryContext
                             createCGImage:ciImage
                             fromRect:CGRectMake(0, 0,
                                                 CVPixelBufferGetWidth(imageBuffer),
                                                 CVPixelBufferGetHeight(imageBuffer))];
    
    UIImage *image = [[UIImage alloc] initWithCGImage:videoImage];
    CGImageRelease(videoImage);
    
    return image;
}

EnvConstant.h:

/**
 *  常量类
 */
#define IS_IOS_7 ([[[UIDevice currentDevice] systemVersion] floatValue] >=7.0 ? YES : NO)
#define IS_IOS_8 ([[[UIDevice currentDevice] systemVersion] floatValue] >=8.0 ? YES : NO)
#define IS_IPHONE5 (([[UIScreen mainScreen] bounds].size.height-568)?NO:YES)
#define WIDTH ([[UIScreen mainScreen] bounds].size.width)
#define HEIGHT ([[UIScreen mainScreen] bounds].size.height)
#define START_POSITION ([[[UIDevice currentDevice] systemVersion] floatValue] >=7.0 ? 20 : 0)

需要引入 CoreMedia, CoreVideo QuartzCore, AVFoundation 四个framework