AHDataTaskManager.donwload(fileName: "testURL4.mp3", url: testURL4, fileSizeCallback: { (fileSize) in
/// store the file size if needed
}, progressCallback: { (progress) in
/// the progress will only be updated when the percent whole number changes,
/// e.g. from %33 to %34, not for those from %33.33 to %33.99.
/// Otherwise the main thread is going to be filled up with those progress updates.
}, successCallback: { (filePath) in
print("testURL4 ok, path:\(filePath)")
}) { (error) in
print("testURL4 failed error:\(String(describing: error))")
}

public static func getCurrentTaskURLs() -> [String]
public static func getState(_ urlStr: String) -> AHDataTaskState
public static func getTaskTempFilePath(_ urlStr: String) -> String?
public static func getTaskCacheFilePath(_ urlStr: String) -> String?

AHFileSizeProbe.probe(urlStr: testURL4) { (size) in
print("single size:\(size)")
}

let fileUrls = [testURL1,testURL2,testURL3,testURL4]
AHFileSizeProbe.probeBatch(urlStrs: [testURL1,testURL2,testURL3,testURL4]) { (sizeDict) in
/// NOTE: the sizeDict is a map from the ORIGINAL download url you passed in, to its file size.
for (offset: i, element: (key: url, value: fileSize)) in sizeDict.enumerated() {
print("url:\(value) fileSize:\(fileSize)")
}
}