iOS丰富通知:发送MP4文件会生成透明的缩略图

Question

我刚刚在我的iOS应用程序的推送通知中添加了MP4/GIF附件。就回放而言，一切都很正常。我面临的问题是，当发送MP4视频时，推送中发送的小缩略图看起来是透明的。然而，当我扩展它时，它看起来很完美，我也可以在推送中玩得很好。当我发送同样的视频转换为GIF，缩略图也看起来很完美。

下面是一个示例：

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上面的例子展示了两个不同的应用程序，只是为了展示MP4和GIF缩略图是如何在同一个活动中出现的。如果我将GIF发送到顶部的应用程序，缩略图的输出看起来与Pushover应用程序的缩略图一模一样。

这是当我滑动并查看缩略图(透明的)时发生的事情。这个特殊的扩展缩略图用于不同的事件(我失去了那个旧事件)。但我想说的是，展开后的视图看起来很完美。而且玩得也很完美。

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所以总而言之，在IOS中，当我以附件的形式发送MP4文件时，小的缩略图看起来是透明的，但播放效果很好。展开的缩略图看起来很完美。

这是我的客户端代码：

    //
//  NotificationService.m
//  NotificationService
//
//  
//
//
// Credit https://github.com/Leanplum/Leanplum-iOS-Samples/blob/master/iOS_basicSetup/basicSetup/richPushExtension/NotificationService.m

#import "NotificationService.h"

@interface NotificationService ()

@property (nonatomic, strong) void (^contentHandler)(UNNotificationContent *contentToDeliver);
@property (nonatomic, strong) UNMutableNotificationContent *bestAttemptContent;

@end

@implementation NotificationService


- (void)didReceiveNotificationRequest:(UNNotificationRequest *)request withContentHandler:(void (^)(UNNotificationContent * _Nonnull))contentHandler {
    self.contentHandler = contentHandler;
    self.bestAttemptContent = [request.content mutableCopy];
    NSDictionary *userInfo = request.content.userInfo;


    // If there is no image in the payload than
    // the code will still show the push notification.
    if (userInfo == nil || userInfo[@"image_url_jpg"] == nil) {
        NSLog(@"zmNinja Notification: Did not get a payload or image");
        [self contentComplete];
        return;
    }

    NSString *mediaUrl = userInfo[@"image_url_jpg"];
   // if (mediaType == nil) {
   //   NSLog(@"zmNinja Notification: No media type specified, assuming .jpg");
  //    mediaType = @".jpg";
  //  }

    // load the attachment
    [self loadAttachmentForUrlString:mediaUrl

                   completionHandler:^(UNNotificationAttachment *attachment) {
                       if (attachment) {
                           self.bestAttemptContent.attachments = [NSArray arrayWithObject:attachment];
                       }
                       [self contentComplete];
                   }];

}

- (NSString*)determineType:(NSString *) fileType {
    // Determines the file type of the attachment to append to NSURL.
    //return @".gif";
      // Determines the file type of the attachment to append to NSURL.
    NSLog (@"zmNinja Notification: determineType got filetype=%@",fileType);
    if ([fileType isEqualToString:@"image/jpeg"]){
        NSLog (@"zmNinja Notification: returning JPG");
        return @".jpg";
    }
    if ([fileType isEqualToString:@"video/mp4"]){
        NSLog (@"zmNinja Notification: returning MP4");
        return @".mp4";
    }

    if ([fileType isEqualToString:@"image/gif"]) {
         NSLog (@"zmNinja Notification: returning GIF");
        return @".gif";
    }
    if ([fileType isEqualToString:@"image/png"]) {
         NSLog (@"zmNinja Notification: returning PNG");
        return @".png";

    }
     NSLog (@"zmNinja Notification: unrecognized filetype, returning JPG");
    return @".jpg";


}

- (void)loadAttachmentForUrlString:(NSString *)urlString 
                 completionHandler:(void(^)(UNNotificationAttachment *))completionHandler  {

    __block UNNotificationAttachment *attachment = nil;
    NSURL *attachmentURL = [NSURL URLWithString:urlString];

    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
    [[session downloadTaskWithURL:attachmentURL
                completionHandler:^(NSURL *temporaryFileLocation, NSURLResponse *response, NSError *error) {
                    if (error != nil) {

                        NSLog(@"unable to add attachment: %@", error.localizedDescription);

                    } else {
                        NSString *fileType = [self determineType: [response MIMEType]];
                        NSFileManager *fileManager = [NSFileManager defaultManager];
                        NSURL *localURL = [NSURL fileURLWithPath:[temporaryFileLocation.path stringByAppendingString:fileType]];
                        [fileManager moveItemAtURL:temporaryFileLocation toURL:localURL error:&error];

                        NSError *attachmentError = nil;
                        attachment = [UNNotificationAttachment attachmentWithIdentifier:@"" URL:localURL options:nil error:&attachmentError];
                        if (attachmentError) {

                            NSLog(@"unable to add attchment: %@", attachmentError.localizedDescription);

                        }
                    }
                    completionHandler(attachment);
                }] resume];
}

- (void)contentComplete {
    self.contentHandler(self.bestAttemptContent);
}

- (void)serviceExtensionTimeWillExpire {
    // Called just before the extension will be terminated by the system.
    // Use this as an opportunity to deliver your "best attempt" at modified content, otherwise the original push payload will be used.
    NSLog (@"zmNinja Notification: Time about to expire, handing off to best attempt");
    self.contentHandler(self.bestAttemptContent);
}

@end

服务器端使用FCM传统API：

my $ios_message = {
    to           => $obj->{token},
    notification => {
      title => $title,
      body  => $body,
      sound => "default",
      badge => $badge,
    },
    data => {
      myMessageId => $notId,
      mid         => $mid,
      eid         => $eid,
      summaryText => $eid
    }
  };
  $ios_message->{data}->{image_url_jpg} = $pic; # $pic is a URL for the mp4
  # image_url_jpg is just a field name. It was originally meant for static images
  # haven't changed it yet, as you see in client code above, it uses that field.
  $json = encode_json($ios_message);
  my $req = HTTP::Request->new( 'POST', $uri );
  $req->header(
    'Content-Type'  => 'application/json',
    'Authorization' => $key
  );
  $req->content($json);
  my $lwp = LWP::UserAgent->new(%ssl_push_opts);
  my $res = $lwp->request($req);

最后，如果你想看一个样例MP4来排除任何格式问题，这是我上传到google drive (link)的一个例子。我已经用ffshow提取了帧信息，它对我来说并不是不合适的(而且它播放得很好)。

有没有人能告诉我为什么最初的小缩略图在iOS中看起来乱七八糟？(如果有帮助，我在iOS 13.x上)谢谢。

Answer 1

也有同样的问题。通过创建notification content extension并将缩略图地址与视频地址一起发送解决了此问题。

在服务扩展中，我添加了视频和缩略图作为附件，缩略图作为第一个元素，iOS将在通知预览中显示该元素：

// mediaAttachment and thumbnailAttachment are UNNotificationAttachments 
// that have just been downloaded
if let mediaAttachment = mediaAttachment {
    mutableContent.attachments = [mediaAttachment]
}
if let thumbnailAttachment = thumbnailAttachment {
    mutableContent.attachments.insert(thumbnailAttachment, at: 0)
}
contentHandler(mutableContent)

扩展的通知UI由替换默认UI的内容扩展来处理，我忽略了缩略图，只显示视频，这将是最后一个附件。