带有 UIImage 或远程 URL 的 UNNotificationAttachment

Question

在我的Notification Service Extension 中，我正在从 URL 下载图像以在通知中显示为 UNNotificationAttachment。

所以我有这个图像作为 UIImage 并且看不到需要将它写入我的应用程序目录/磁盘上的组容器中只是为了设置通知。

有没有用 UIImage 创建 UNNotificationAttachment 的好方法？ （应该适用于本地和远程通知）

Answer 1

1. 在 tmp 文件夹中创建目录
2. 将UIImage 的NSData 表示写入新创建的目录中
3. 在 tmp 文件夹中创建带有 url 的 UNNotificationAttachment 文件
4. 清理 tmp 文件夹

我在UINotificationAttachment上写了一个扩展

extension UNNotificationAttachment {

    static func create(identifier: String, image: UIImage, options: [NSObject : AnyObject]?) -> UNNotificationAttachment? {
        let fileManager = FileManager.default
        let tmpSubFolderName = ProcessInfo.processInfo.globallyUniqueString
        let tmpSubFolderURL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(tmpSubFolderName, isDirectory: true)
        do {
            try fileManager.createDirectory(at: tmpSubFolderURL, withIntermediateDirectories: true, attributes: nil)
            let imageFileIdentifier = identifier+".png"
            let fileURL = tmpSubFolderURL.appendingPathComponent(imageFileIdentifier)
            let imageData = UIImage.pngData(image)
            try imageData()?.write(to: fileURL)
            let imageAttachment = try UNNotificationAttachment.init(identifier: imageFileIdentifier, url: fileURL, options: options)
            return imageAttachment
        } catch {
            print("error " + error.localizedDescription)
        }
        return nil
    }
}

所以要从UNUserNotificationAttachment 创建UNUserNotificationRequest UIImage 你可以简单地这样做

let identifier = ProcessInfo.processInfo.globallyUniqueString
let content = UNMutableNotificationContent()
content.title = "Hello"
content.body = "World"
if let attachment = UNNotificationAttachment.create(identifier: identifier, image: myImage, options: nil) {
    // where myImage is any UIImage
    content.attachments = [attachment] 
}
let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 120.0, repeats: false)
let request = UNNotificationRequest.init(identifier: identifier, content: content, trigger: trigger)
UNUserNotificationCenter.current().add(request) { (error) in
    // handle error
}

这应该可以工作，因为UNNotificationAttachment 会将图像文件复制到自己的位置。

Answer 2

我已经创建了一篇关于这个主题的博文，专注于 GIF 图像。但是为简单的图像重写我的代码应该很容易。

您需要创建一个通知服务扩展：

并包含以下代码：

final class NotificationService: UNNotificationServiceExtension {

    private var contentHandler: ((UNNotificationContent) -> Void)?
    private var bestAttemptContent: UNMutableNotificationContent?

    override internal func didReceiveNotificationRequest(request: UNNotificationRequest, withContentHandler contentHandler: (UNNotificationContent) -> Void){
        self.contentHandler = contentHandler
        bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)

        func failEarly() {
            contentHandler(request.content)
        }

        guard let content = (request.content.mutableCopy() as? UNMutableNotificationContent) else {
            return failEarly()
        }

        guard let attachmentURL = content.userInfo["attachment-url"] as? String else {
            return failEarly()
        }

        guard let imageData = NSData(contentsOfURL:NSURL(string: attachmentURL)!) else { return failEarly() }
        guard let attachment = UNNotificationAttachment.create("image.gif", data: imageData, options: nil) else { return failEarly() }

        content.attachments = [attachment]
        contentHandler(content.copy() as! UNNotificationContent)
    }

    override func 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.
        if let contentHandler = contentHandler, let bestAttemptContent =  bestAttemptContent {
            contentHandler(bestAttemptContent)
        }
    }

}

extension UNNotificationAttachment {

    /// Save the image to disk
    static func create(imageFileIdentifier: String, data: NSData, options: [NSObject : AnyObject]?) -> UNNotificationAttachment? {
        let fileManager = NSFileManager.defaultManager()
        let tmpSubFolderName = NSProcessInfo.processInfo().globallyUniqueString
        let tmpSubFolderURL = NSURL(fileURLWithPath: NSTemporaryDirectory()).URLByAppendingPathComponent(tmpSubFolderName, isDirectory: true)

        do {
            try fileManager.createDirectoryAtURL(tmpSubFolderURL!, withIntermediateDirectories: true, attributes: nil)
            let fileURL = tmpSubFolderURL?.URLByAppendingPathComponent(imageFileIdentifier)
            try data.writeToURL(fileURL!, options: [])
            let imageAttachment = try UNNotificationAttachment.init(identifier: imageFileIdentifier, URL: fileURL!, options: options)
            return imageAttachment
        } catch let error {
            print("error \(error)")
        }

        return nil
    }
}

有关更多信息，您可以在此处查看我的博文： http://www.avanderlee.com/ios-10/rich-notifications-ios-10/

Answer 3

这是一个完整的示例，如何实际从互联网下载图像并将其附加到本地通知（这是原始问题的一部分）。

let content = UNMutableNotificationContent()
content.title = "This is a test"
content.body = "Just checking the walls"

if let url = URL(string: "https://example.com/images/example.png") {

    let pathExtension = url.pathExtension

    let task = URLSession.shared.downloadTask(with: url) { (result, response, error) in
        if let result = result {

            let identifier = ProcessInfo.processInfo.globallyUniqueString                
            let target = FileManager.default.temporaryDirectory.appendingPathComponent(identifier).appendingPathExtension(pathExtension)

            do {
                try FileManager.default.moveItem(at: result, to: target)

                let attachment = try UNNotificationAttachment(identifier: identifier, url: target, options: nil)
                content.attachments.append(attachment)

                let notification = UNNotificationRequest(identifier: Date().description, content: content, trigger: trigger)
                UNUserNotificationCenter.current().add(notification, withCompletionHandler: { (error) in
                    if let error = error {
                        print(error.localizedDescription)
                    }
                })
            }
            catch {
                print(error.localizedDescription)
            }
        }
    }
    task.resume()
}

当下载的文件已经是有效图像时，通常不需要重新创建图像。只需将下载的文件复制到具有唯一名称和.png 或.jpg 扩展名的当前临时目录即可。也不必在现有的 Temp 目录中创建子目录。

Answer 4

来自UIImage 似乎不可能，我找到的所有解决方案都是下载图像并将其存储在本地某处。这也很有意义，因为您必须导入 UIKit 并且不确定它是否与扩展兼容（以及为什么在有更简单的解决方案时导入整个框架）。

Here 是一种更简单且可测试的解决方案，无需使用 FileManager。