自定义相机（一） -- 预览视频流

实现功能：

　　自定义视频流，实时预览。

运行环境：

　　1.  XCODE 5.1.1

　　2.  真机（IPHONE5  ,  IOS6.1.4）

#import <UIKit/UIKit.h>

#import <AVFoundation/AVFoundation.h>       //导入 - "视频流"

@interface MCViewController : UIViewController
@property (strong, nonatomic) AVCaptureSession * captureSession;    //AVCaptureSession实例

@property (strong, nonatomic) AVCaptureDeviceInput * videoInput;    //持有视频输入实例
@end

#import "MCViewController.h"

@interface MCViewController ()
@end
@implementation MCViewController
- (void)viewWillAppear:(BOOL)animated

{

    [super viewWillAppear:animated];
//开始扑捉会话

    [self.captureSession startRunning];

}
- (void)viewWillDisappear:(BOOL)animated

{

    [super viewWillDisappear:animated];
//停止扑捉会话

    [self.captureSession stopRunning];

}
- (void)viewDidLoad

{

    [super viewDidLoad];
//1.1 创建AVCaptureSession

    self.captureSession = [[AVCaptureSession alloc] init];

    //1.2 指定输入设备。这里使用后摄像头。

    AVCaptureDevice * device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    //1.3 创建AVCaptureDeviceInput的实例，将所选设备作为扑捉会话的输入。

    //      此外，在将是其添加到回话前请创建好输入，这里需要做个检查。

    NSError * error = nil;

    self.videoInput = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];

    if (self.videoInput) {

        [self.captureSession addInput:self.videoInput];

    }

    else

    {

        NSLog(@"input error : %@", error);

    }
//2. 创建预览层

    AVCaptureVideoPreviewLayer * previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];

    UIView * aView = self.view;

    previewLayer.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);

    [aView.layer addSublayer:previewLayer];
}
@end

自定义相机（一） -- 预览视频流