thumbnailImageAtTime: now deprecated - What's

问题:

Until iOS7 update I was using...

UIImage *image = [moviePlayer thumbnailImageAtTime:1.0 timeOption:MPMovieTimeOptionNearestKeyFrame];

...with great success, so that my app could show a still of the video that the user had just taken.

I understand this method, as of iOS7 has now deprecated and I need an alternative. I see there's a method of

- (void)requestThumbnailImagesAtTimes:(NSArray *)playbackTimes timeOption:(MPMovieTimeOption)option

though how do I return the image from it so I can place it within the videoReview button image?

Thanks in advance, Jim.

****Edited question, after trying notification centre method***

I used the following code -

[moviePlayer requestThumbnailImagesAtTimes:times timeOption:MPMovieTimeOptionNearestKeyFrame];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(MPMoviePlayerThumbnailImageRequestDidFinishNotification::) name:MPMoviePlayerThumbnailImageRequestDidFinishNotification object:moviePlayer];

I made the NSArray times of two NSNumber objects 1 & 2.

I then tried to capture the notification in the following method

-(void)MPMoviePlayerThumbnailImageRequestDidFinishNotification: (NSDictionary*)info{

UIImage *image = [info objectForKey:MPMoviePlayerThumbnailImageKey];

Then proceeded to use this thumbnail image as the button image as a preview.... but it didn't work.

If you can see from my coding where I've went wrong your help would be appreciated again. Cheers

回答1:

Managed to find a great way using AVAssetImageGenerator, please see code below...

AVURLAsset *asset1 = [[AVURLAsset alloc] initWithURL:partOneUrl 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];
[_firstImage setImage:one];
_firstImage.contentMode = UIViewContentModeScaleAspectFit;

Within header file, please import

#import <AVFoundation/AVFoundation.h>

It works perfect and I've been able to call it from viewDidLoad, which was quicker than calling the deprecated thumbNailImageAtTime: from the viewDidAppear.

Hope this helps anyone else who had the same problem.

回答2:

The requestThumbnailImagesAtTimes:timeOption: method will post a MPMoviePlayerThumbnailImageRequestDidFinishNotification notification when an image request completes. Your code that needs the thumbnail image should subscribe to this notification using NSNotificationCenter, and use the image when it receives the notification.

回答3:

The problem is that you have to specify float values in requestThumbnailImagesAtTimes.

For example, this will work

[self.moviePlayer requestThumbnailImagesAtTimes:@[@14.f] timeOption:MPMovieTimeOptionNearestKeyFrame];

but this won't work:

[self.moviePlayer requestThumbnailImagesAtTimes:@[@14] timeOption:MPMovieTimeOptionNearestKeyFrame];

回答4:

The way to do it, at least in iOS7 is to use floats for your times

NSNumber *timeStamp = @1.f;
[moviePlayer requestThumbnailImagesAtTimes:timeStamp timeOption:MPMovieTimeOptionNearestKeyFrame];

Hope this helps

回答5:

Jeely provides a good work around but it requires an additional library that isn't necessary when the MPMoviePlayer already provides functions for this task. I noticed a syntax error in the original poster's code. The thumbnail notification handler expects an object of type NSNotification, not a dictionary object. Here's a corrected example:

-(void)MPMoviePlayerThumbnailImageRequestDidFinishNotification: (NSNotification*)note
{
    NSDictionary * userInfo = [note userInfo];
    UIImage *image = (UIImage *)[userInfo objectForKey:MPMoviePlayerThumbnailImageKey];
    if(image!=NULL)
        [thumbView setImage:image];
}

回答6:

I've just looked for a solution for this problem myself and got good help from your question. Got your code above to work with one small change, removed a colon...

Change

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(MPMoviePlayerThumbnailImageRequestDidFinishNotification::) name:MPMoviePlayerThumbnailImageRequestDidFinishNotification object:moviePlayer];

to

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(MPMoviePlayerThumbnailImageRequestDidFinishNotification:) name:MPMoviePlayerThumbnailImageRequestDidFinishNotification object:moviePlayer];

Got this to work nicely. Also, I've found that you can't call a method the rely on NotificationCenter if you're already in a notification selector. Something I tried at first - I tried calling requestThumbnailImagesAtTimes inside the notification selector for MPMoviePlayerPlaybackDidFinishNotification - something that won't work. I think because the notification won't fire.

回答7:

The code in Swift 2.1 would look like this:

do{
    let asset1 =  AVURLAsset(URL: url)
    let generate1: AVAssetImageGenerator = AVAssetImageGenerator(asset: asset1)
    generate1.appliesPreferredTrackTransform = true

    let time: CMTime = CMTimeMake(3, 1)  //TO CATCH THE THIRD SECOND OF THE VIDEO
    let oneRef: CGImageRef = try generate1.copyCGImageAtTime(time, actualTime: nil)
    let resultImage = UIImage(CGImage: oneRef)
}
catch let error as NSError{
    print(error)
}