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[英]When downloading a javascript file from the internet, where does it go?
[英]When attaching thumbnails to notifications, where does the file go?
我正在向豐富的通知添加縮略圖。 我生成要用作附件的圖像,如下所示:
let url = URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true)
let fileURL = url.appendingPathComponent("someImageName", isDirectory: false).appendingPathExtension("png")
do{
try UIImagePNGRepresentation(image)?.write(to: fileURL)
}catch{
print("Could not write: ", error)
}
這是成功的。 如果我現在運行此代碼:
let content = try? FileManager.default.contentsOfDirectory(atPath: NSTemporaryDirectory())
print(content ?? "error")
它打印出這個: ["someImageName.png"]
。
然后我創建附件,如下所示:
let attachment = try? UNNotificationAttachment(identifier: "image", url: url, options: nil)
let content = UNMutableNotificationContent()
content.title = "Test"
content.attachments = [attachment!]
let request = UNNotificationRequest(identifier: "someID", content:content, trigger: /*someTrigger*/)
UNUserNotificationCenter.current().add(request, withCompletionHandler:...)
這一切都在起作用。 發送通知,並附加附件。 但是如果我現在打印出我的臨時文件夾的內容,它是空的! 我之前保存的圖像已從此文件夾中刪除。
經過大量的反復試驗,我發現在我添加通知時圖像已被刪除。 為什么我的通知會刪除我的圖片? 我找不到任何關於此的文檔!
如果我做了以上所有操作,但注釋掉這一行: //content.attachments = [attachment!]
,這意味着我存儲的圖像不會作為附件添加到我的通知中,那么我的圖像不會從臨時文件夾中刪除!
這些文件在使用后會被清理嗎? 或者我是否必須在通知消失后查看不同的文件夾並手動清理它們? 我不希望我的應用程序創建數百個永遠不會再使用的圖像,而無法刪除它們。
這些天我面臨同樣的問題,答案在文檔中,乍一看不是很容易,但它就在那里:
關於UNNotificationAttachment :
...驗證后,附加文件將移入附件數據存儲,以便所有適當的進程都可以訪問它們。
關於 init 方法:
當您安排包含附件的通知請求時,附件的文件將移動到新位置以方便適當進程訪問。 移動后,訪問文件的唯一方法是使用 UNUserNotificationCenter 對象的方法。
請注意:
位於應用程序包內的附件被復制而不是移動。
所以我決定:
像您一樣編寫文件並在NSTemporaryDirectory()
中NSTemporaryDirectory()
它的副本我使用這個示例輕松創建和刪除 TempDirectory (Swift 4.0)(感謝Ole Begemman ):
import Foundation
/// A wrapper around a temporary file in a temporary directory. The directory
/// has been especially created for the file, so it's safe to delete when you're
/// done working with the file.
///
/// Call `deleteDirectory` when you no longer need the file.
struct TemporaryFile {
let directoryURL: URL
let fileURL: URL
/// Deletes the temporary directory and all files in it.
let deleteDirectory: () throws -> Void
/// Creates a temporary directory with a unique name and initializes the
/// receiver with a `fileURL` representing a file named `filename` in that
/// directory.
///
/// - Note: This doesn't create the file!
init(creatingTempDirectoryForFilename filename: String) throws {
let (directory, deleteDirectory) = try FileManager.default
.urlForUniqueTemporaryDirectory()
self.directoryURL = directory
self.fileURL = directory.appendingPathComponent(filename)
self.deleteDirectory = deleteDirectory
}
}
extension FileManager {
/// Creates a temporary directory with a unique name and returns its URL.
///
/// - Returns: A tuple of the directory's URL and a delete function.
/// Call the function to delete the directory after you're done with it.
///
/// - Note: You should not rely on the existence of the temporary directory
/// after the app is exited.
func urlForUniqueTemporaryDirectory(preferredName: String? = nil) throws
-> (url: URL, deleteDirectory: () throws -> Void)
{
let basename = preferredName ?? UUID().uuidString
var counter = 0
var createdSubdirectory: URL? = nil
repeat {
do {
let subdirName = counter == 0 ? basename : "\(basename)-\(counter)"
let subdirectory = temporaryDirectory
.appendingPathComponent(subdirName, isDirectory: true)
try createDirectory(at: subdirectory, withIntermediateDirectories: false)
createdSubdirectory = subdirectory
} catch CocoaError.fileWriteFileExists {
// Catch file exists error and try again with another name.
// Other errors propagate to the caller.
counter += 1
}
} while createdSubdirectory == nil
let directory = createdSubdirectory!
let deleteDirectory: () throws -> Void = {
try self.removeItem(at: directory)
}
return (directory, deleteDirectory)
}
}
使用 TempURL 附加文件后,文件將被移動,您可以刪除 TempDirectory。
后來進行了一些測試,可以肯定的是,我終於發現我的文件(在我的情況下是圖像)存儲在這里:
URL: file:///var/mobile/Library/SpringBoard/PushStore/Attachments/com.YourApp.Name/8e52c6673f6e735f83535486bf750ba1118a3ade.png
提交或清理通知中心后,文件被刪除是。
為什么這一切? -> 沙盒! 當我將我的文件附加到觸發器(此處為 UNCalendarNotificationTrigger)時,我將負責我的文件的日歷命名為在我的通知中顯示它,但要處理它,它必須將文件放在 HIS 目錄中。
希望它有所幫助,我花了一段時間才找到所有的奧秘!
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