ios - MediaPlayer -requestThumbnailImagesAtTimes 未触发通知
<p><p>我无法使用 <code>MPMoviePlayerController</code> 从电影中提取缩略图图像 </p>
<p><code>-requestThumbnailImagesAtTimes: timeOption:</code></p>
<p>我 99% 确定我已正确设置所有内容；我根本没有收到这些通知。</p>
<p>我最初在 <code>ReactiveCocoa</code> 工作；为了缩小可能性，我有一个没有它的最小损坏示例。</p>
<h3>最小损坏示例:</h3>
<pre><code>@import MediaPlayer;
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
// 1. register the observer before requesting the thumbnails
[ addObserverForName:MPMoviePlayerThumbnailImageRequestDidFinishNotification object:nil queue:nil usingBlock:^(NSNotification *note) {
// 4. this never gets hit
NSLog(@"%@", note.name);
}];
// 2. this works fine - media url is correct etc
MPMoviePlayerController *moviePlayer = [ initWithContentURL:];
// 3. previously was using integers instead of floats; fixed that but this still doesn't do anything
timeOption:MPMovieTimeOptionExact];
// ...
}
</code></pre>
<h3>ReactiveCocoa 中的原始示例</h3>
<pre><code>@import MediaPlayer;
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
// 1. set the file URL
self.viewModel.movieURL = ;
// ...
}
// in viewmodel
- (void)viewDidLoad {
RACSignal *moviePlayerSignal = [ map:^id(NSURL *url) {
// 2. this allocates correctly
return [ initWithContentURL:url];
}];
// 3. observe the moviePlayerSignal;
[[[moviePlayerSignal map:^id(MPMoviePlayerController *player) {
@strongify(self);
NSLog(@"%@", player); // checking that the player exists etc - it does; all good here.
// register the observer before we request the thumbnail
RACSignal *notification = [[ rac_addObserverForName:MPMoviePlayerThumbnailImageRequestDidFinishNotification object:player] takeUntil:];
// request the thumbnail
timeOption:MPMovieTimeOptionExact];
// map the signal into a stream of signals on the observer
return notification;
// if we subscribeNext without flattening we correctly get back RACSignals every time
}] flatten] subscribeNext:^(id x) {
// the flattened signal never gets a next because the player isn't firing notifications :(
NSLog(@"WHY DOESN'T THIS WORK!?");
}];
}
</code></pre></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><pre><code>[ addObserver:self
selector:@selector(didReceiveImage:)
name:MPMoviePlayerThumbnailImageRequestDidFinishNotification
object:self.player];
</code></pre>
<p>查看通知的对象。
您需要将其设置为 MPMoviePlayerController。
所以必须写在MPMoviePlayerController的首字母之后。</p></p>
<p style="font-size: 20px;">关于ios - MediaPlayer -requestThumbnailImagesAtTimes 未触发通知，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/25064253/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/25064253/
</a>
</p>
页:
[1]