iphone - 在后台运行时像 Pastebot 一样抓取 UIPasteboard

Question

我知道这是可能的，因为 Tapbots Pastebot 就是这样做的。我试图在我的 iPhone 应用程序在后台运行时抓取 UIPasteboard 并将其添加到 UITableView 中，就像 Pastebot 所做的那样，但我也尝试缩短链接(如果它是 URL)并将其复制回 UIPastboard 以便准备就绪供用户粘贴到任何地方。现在，Pastebot 显然在后台运行，播放音频文件 10 分钟。我已经在 applicationDidFinishLaunching 中设置了 NSNotificationCenter

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(pasteboardChangedNotification:) name:UIPasteboardChangedNotification object:[UIPasteboard generalPasteboard]];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(pasteboardChangedNotification:) name:UIPasteboardRemovedNotification object:[UIPasteboard generalPasteboard]];

- (void)pasteboardChangedNotification:(NSNotification*)notification {
pasteboardChangeCount_ = [UIPasteboard generalPasteboard].changeCount; 
}

- (void)applicationDidBecomeActive:(UIApplication *)application
{
     if (pasteboardChangeCount_ != [UIPasteboard generalPasteboard].changeCount) {
    [[NSNotificationCenter defaultCenter] postNotificationName:UIPasteboardChangedNotification object:[UIPasteboard generalPasteboard]];
     }
}

任何人都可以指导我获取 UIPasteboard 并缩短链接(如果它是 URL)并将其发送回 UIPasteboard 吗？我已阅读多任务开发文档和 UIPasteboard 文档。如果有人有解决方案可以分享给我吗？

谢谢

Answer 1

我成功实现类似目标的唯一方法是不打扰 NSNotificationCenter ，而是在后台定期复制 UIPasteboard 的内容.

下面的代码每秒检查一次UIPasteboard，持续一千秒。我相信应用程序可以在后台运行大约 10 分钟而不播放音频。如果您在后台播放音频文件，应用程序可以继续运行。

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    // Create a background task identifier
    __block UIBackgroundTaskIdentifier task; 
    task = [application beginBackgroundTaskWithExpirationHandler:^{
        NSLog(@"System terminated background task early"); 
        [application endBackgroundTask:task];
    }];

    // If the system refuses to allow the task return
    if (task == UIBackgroundTaskInvalid)
    {
        NSLog(@"System refuses to allow background task");
        return;
    }

    // Do the task
    dispatch_async(dispatch_get_global_queue(0, 0), ^{

        NSString *pastboardContents = nil;

        for (int i = 0; i < 1000; i++) 
        {
            if (![pastboardContents isEqualToString:[UIPasteboard generalPasteboard].string]) 
            {
                pastboardContents = [UIPasteboard generalPasteboard].string;
                NSLog(@"Pasteboard Contents: %@", pastboardContents);
            }

            // Wait some time before going to the beginning of the loop
            [NSThread sleepForTimeInterval:1];
        }

        // End the task
        [application endBackgroundTask:task];
    });


}