Unable to display thumbnail in another view controller

Question

- (void)displayThumbnail
{
    AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:[self outputURL] options:nil];
    AVAssetImageGenerator *gen = [[AVAssetImageGenerator alloc] initWithAsset:asset];
    gen.appliesPreferredTrackTransform = YES;
    CMTime time = CMTimeMakeWithSeconds(1, 30);
    NSError *error = nil;
    CMTime actualTime;
    CGImageRef imageref = [gen copyCGImageAtTime:time actualTime:&actualTime error:&error];
    UIImage *thumbnail = [[UIImage alloc] initWithCGImage:imageref];
    CGImageRelease(imageref);

    UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];

    MainViewController *controller = [mainStoryboard instantiateViewControllerWithIdentifier:@"MainViewController"];

    controller.imageView.image = thumbnail;
}

I'm attempting to display a thumbnail of a recorded video in another view controller, but nothing shows up. Am I missing something?

How about instead of trying to set the image from your method. Just pass in a UIImage to the next view controller. And then in that viewcontroller use ```setImage``` to set that UIImage in the UIimageView? — , Jun 10 '15 at 08:07
Also maybe the image is nil or something? You should do some checks before passing it in to the next view controller. Check ```error``` before you send in the image. Also check if ```thumbnail != nil``` before passing it to the next controller. — , Jun 10 '15 at 08:09
It could be that the code is fine but AVAsset does not have the correct file path for the video and thus your not getting a thumbnail, thus why i think its important that you check the ```error``` and whether ```thumbnail``` is nil or not. — , Jun 10 '15 at 08:10
Good points. Will work on your suggestions and update soon. Thanks Dan — Arvin Sanmuga Rajah, Jun 10 '15 at 08:16
When U load UIViewController from the storyboard, its view isn't loaded yet (i.e. viewDidLoad() isn't called). It means that controller.imageView is nil. Solution: create a standalone UIImage property in your target controller .h file and set it to the self.imageView.image in MainViewController's viewDidLoad() — David, Jun 10 '15 at 08:30
@David Yeah I was thinking about that. So it makes sense to just pass the UIimage data and let the viewcontroller itself set the imageview. — , Jun 10 '15 at 09:06

score 1 · Answer 1 · answered Jun 10 '15 at 08:20

1

Take property of UIImage type in MainViewController.h

@property(strong,nonatomic) UIImage* thumbnailImg;

in MainViewController.m

self.imageView.image = self.thumbnailImg;

set this property

[controller setThumbnailImg: thumbnail]

answered Jun 10 '15 at 08:20

Vikash Rajput

445
5
21

Bhadresh Mulsaniya · Answer 2 · 2015-06-10T10:07:30.620

0

I think your path is wrong which you have stored in [self outputURL]. Can you paste video path here?

Try this code:

AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:[self outputURL] options:nil];
AVAssetImageGenerator *gen = [[AVAssetImageGenerator alloc] initWithAsset:asset];
gen.appliesPreferredTrackTransform = YES;
int time = CMTimeGetSeconds ([asset duration]) /2;
NSError *error = nil;
CMTime actualTime;

CGImageRef image = [gen copyCGImageAtTime:CMTimeMake(time, 1) actualTime:&actualTime error:&error];
thumb = [UIImage imageWithCGImage:image];
[UIImagePNGRepresentation(thumb) writeToFile:imgPath atomically:YES];
        CGImageRelease(image);

edited Jun 10 '15 at 10:07

answered Jun 10 '15 at 09:20

Bhadresh Mulsaniya

2,610
1
12
25

- (NSURL *)outputURL { NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]; filePath = [documentsDirectory stringByAppendingPathComponent:VIDEO_FILE]; return [NSURL fileURLWithPath:filePath]; } – Arvin Sanmuga Rajah Jun 10 '15 at 09:53
I think you have made wrong time here CMTime time = CMTimeMakeWithSeconds(1, 30); – Bhadresh Mulsaniya Jun 10 '15 at 10:07
Tried. Still not displaying :( – Arvin Sanmuga Rajah Jun 10 '15 at 15:03
Can you NSLog [self outputURL] here?? – Bhadresh Mulsaniya Jun 11 '15 at 04:59
Also check the video is recorded properly or not ? – Bhadresh Mulsaniya Jun 11 '15 at 05:00

score 0 · Answer 3 · edited Jun 10 '15 at 09:58

0

Try this hope it will help you:

controller.imageView.image = [thumbnail copy];

edited Jun 10 '15 at 09:58

Rashad

11,057
4
45
73

answered Jun 10 '15 at 09:37

Sumeet Bajaj

224
2
11

Arvin Sanmuga Rajah · Accepted Answer · 2015-06-18T08:08:06.557

Solved it !

Credits to David and Dan :)

MainViewController.h

@property (weak, nonatomic) IBOutlet UIImageView *thumbnailAV;

MainViewController.m

  AVURLAsset *asset1 = [[AVURLAsset alloc] initWithURL:[self outputURL] options:nil];
  AVAssetImageGenerator *generate1 = [[AVAssetImageGenerator alloc] initWithAsset:asset1];
  generate1.appliesPreferredTrackTransform = YES;
  NSError *err = NULL;
  CMTime time = CMTimeMake(1, 2);
  CGImageRef oneRef = [generate1 copyCGImageAtTime:time actualTime:NULL error:&err];
  UIImage *one = [[UIImage alloc] initWithCGImage:oneRef];

  [self.thumbnailAV setImage:one];    
  [self.view setFrame:CGRectMake(0, 0, 320, 422)];
  self.thumbnailAV.contentMode = UIViewContentModeScaleAspectFit;
}

THCaptureViewController.m

UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];

 MainViewController *controller= [mainStoryboard instantiateViewControllerWithIdentifier:@"MainViewController"];
        [self presentViewController:controller animated:YES completion:nil];

}

Unable to display thumbnail in another view controller

4 Answers4