刷新第二个UIImageView中的摄像机视图

Question

我正在尝试编写应用程序，使主对象每秒刷新到另一个。不幸的是，尝试不在第二个UIImageView上显示任何内容。源代码：

ViewController.h

#import <UIKit/UIKit.h>
@import AVFoundation;

@interface ViewController : UIViewController {
    IBOutlet UIView *vImagePreview;
}

@property(nonatomic, retain) IBOutlet UIView *vImagePreview;
@property(nonatomic, retain) IBOutlet UIImageView *imagePreview;
@property(nonatomic, retain) IBOutlet UIImageView *takePreview;
-(IBAction)scanImage: (UIButton *)sender;
@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController
@synthesize vImagePreview;
- (void)viewDidLoad {
    [super viewDidLoad];
    AVCaptureSession *session = [[AVCaptureSession alloc] init];
    session.sessionPreset = AVCaptureSessionPresetMedium;

    CALayer *viewLayer = self.vImagePreview.layer;
    NSLog(@"viewLayer = %@", viewLayer);

    AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];

    captureVideoPreviewLayer.frame = self.vImagePreview.bounds;
    [self.vImagePreview.layer addSublayer:captureVideoPreviewLayer];
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    NSError *error = nil;
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
    if (!input) {
        // Handle the error appropriately.
        NSLog(@"ERROR: trying to open camera: %@", error);
    }
    [session addInput:input];

    [session startRunning];
    // Do any additional setup after loading the view, typically from a nib.
}
-(IBAction)scanImage:(UIButton *)sender {
    int success = 0;
    while ( success < 5 )
    {
        self.takePreview.image = self.imagePreview.layer;
        NSLog (@"OK");
        sleep(1);
        success++;
    }
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

我期待着提供帮助。