ios - __NSCFString playbackFinished 来自 MPMoviePlayerController 的无法识别的选择器

Question

我在一个名为 MYVideo 的类中使用 MPMoviePlayerController。这是代码:

#import <MediaPlayer/MediaPlayer.h>
#import "MYVideo.h"

@interface MYVideo()
@property (strong, nonatomic) UIView * viewRef;
@property (strong, nonatomic) NSDictionary * contentData;
@property (strong, nonatomic) MPMoviePlayerController * videoController;
@end

@implementation MYVideo
@synthesize contentData,videoController,viewRef;

- (MYVideo*) initIntoView: (UIView*) view withContent:(NSDictionary*)contentDict{
    self=[super init];
    viewRef=view;
    contentData = contentDict;
    NSString *rawUrl = [[NSString alloc] initWithFormat:@"http://....com/app/%@.mp4", [contentDict objectForKey:@"cnid"]];
    NSURL *videoUrl = [[NSURL alloc]initWithString:rawUrl];
    videoController = [[MPMoviePlayerController alloc] initWithContentURL:videoUrl];
    videoController.movieSourceType=MPMovieSourceTypeFile;
    videoController.view.frame = viewRef.bounds;
    [videoController.view setAutoresizingMask:UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight];
    videoController.controlStyle=MPMovieControlStyleNone; 
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(playbackFinished:)
                                                 name:MPMoviePlayerPlaybackDidFinishNotification
                                               object:videoController];
    [viewRef addSubview:videoController.view];
    return self;
}

- (void) playbackFinished: (NSNotification*) notification {
    NSLog(@"playback finished");
    if(videoController){
        [videoController play];
    }
}

- (void) play: (int) offset {
    videoController.initialPlaybackTime=offset;
    [videoController play];
}

- (void) stop {
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                                    name:@"playbackFinished"
                                                  object:nil];
    if(videoController){
        [videoController stop];
    }
}

- (void) destroy {
    if(videoController){
        [videoController stop];
        [videoController.view removeFromSuperview];
    }
}
@end

我的问题是偶尔会出现以下错误:

playback finished
-[__NSCFString playbackFinished:]: unrecognized selector sent to instance 0x1664e6a0

我猜这是由于 MPMoviePlayerController 在该视频类已发布时触发“playbackFinished”通知引起的。我这样想对吗？

事情是，这个 MYVideo 类应该在视频播放时仍然存在，这个错误只发生在视频正在播放并且在控制台日志中我的“播放完成”的 NSLogging 立即在碰撞。此外，我从来没有在没有先删除“playbackFinished”观察者的情况下关闭类(class)。

谁能告诉我为什么我会遇到这个崩溃？

非常感谢。

Answer 1

是的，看起来你没有移除观察者，因为这段代码:

[[NSNotificationCenter defaultCenter] removeObserver:self
                                                name:@"playbackFinished"
                                              object:nil];

应该是:

[[NSNotificationCenter defaultCenter] removeObserver:self
                                                name:@"playbackFinished:"
                                              object:nil];         //  ^

或者更好(因为你并不真正关心被称为什么):

[[NSNotificationCenter defaultCenter] removeObserver:self
                                                name:nil
                                              object:videoController];

同时考虑到您在很多地方使用了像 if (videoController) { ... } 这样的测试，您需要确保它尽快变为 nil:

- (void)destroy {
    if(videoController){
        [videoController stop];
        [videoController.view removeFromSuperview];
        videoController = nil;   // Add
    }
}