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我有一個UITableView列出磁盤上的電影文件。對於每個單元行，都會爲每個可見行分配一個工作程序實例，用於爲電影文件生成縮略圖並獲取行顯示的持續時間。爲什麼MPMovieDurationAvailableNotification只會爲我的MPMoviePlayerController的多個實例調度一次？
對於worker類中的MPMoviePlayerController的每個實例Im正在偵聽來自電影播放器的MPMovieDurationAvailableNotification事件。出於某種原因，這個事件似乎只能從其中一個工作者實例中派發（或者至少Im只能捕獲它）。這是init和listener代碼。有幾條評論內聯。
- (id) initWithRequestAsset:(RequestAsset *)asset {
if (self = [super init]) {
self.requestAsset = asset;
self.moviePlayer = [MPMoviePlayerController alloc];
[self setupMoviePlayerListeners];
[self.moviePlayer initWithContentURL:self.requestAsset.urlPath];
self.moviePlayer.shouldAutoplay = NO;
// I've also tried to retain the moviePlayer, to no avail
[self.moviePlayer release];
}
return self;
}
- (void) setupMoviePlayerListeners {
//
// If the object: is set to nil then Im able to catch three notifications, but they are all from last instance of the MPMoviePlayerController
//
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(onMovieDurationAvailable:)
name:MPMovieDurationAvailableNotification
object:self.moviePlayer];
}
- (void) onMovieDurationAvailable:(NSNotification *)notification {
NSLog(@"duration received notification");
self.requestAsset.duration = [[notification object] duration];
[[NSNotificationCenter defaultCenter] removeObserver:self name:MPMovieDurationAvailableNotification object:self.moviePlayer];
}
我在做什麼錯？我想如果我要設置對象：MPMoviePlayerController的實例的參數，它將允許我只獲得該實例的事件。但是，似乎Im只收到最後一次通知。