iOS 10即将发布，因此测试应用程序是否与其兼容是值得的。在此类测试中，我们发现我们的应用无法在iOS10上恢复后台下载。在以前的版本上运行良好的代码在模拟器和设备上都不适用于新版本。
我没有将代码缩减到最小的工作测试用例，而是在互联网上搜索了NSUrlSession教程并对其进行了测试。行为是相同的：恢复工作在iOS的previos版本上，但在10日中断。
下载已恢复。您可以查看iOS10之前版本的工作原理。
下载失败。在xcode控制台中，您可以看到：
2016-09-02 16:11:24.913 HalfTunes[35205:2279228] *** -[NSKeyedUnarchiver initForReadingWithData:]: data is NULL
2016-09-02 16:11:24.913 HalfTunes[35205:2279228] *** -[NSKeyedUnarchiver initForReadingWithData:]: data is NULL
2016-09-02 16:11:24.913 HalfTunes[35205:2279228] Invalid resume data for background download. Background downloads must use http or https and must download to an accessible file.
如果您在下载文件时激活离线模式，则
Url session completed with error: Error Domain=NSURLErrorDomain Code=-1002 "unsupported URL" UserInfo={NSLocalizedDescription=unsupported URL} {
NSLocalizedDescription = "unsupported URL";
}
当网络关闭时，下载永远不会在网络再次启动时恢复。暂停的其他用例（例如重启）也不起作用。
我尝试使用
中建议的代码检查返回的resumeData是否有效How can I check that an NSData blob is valid as resumeData for an NSURLSessionDownloadTask?
但目标文件已到位。虽然resumeData格式已更改，现在文件名存储在NSURLSessionResumeInfoTempFileName中，您必须将NSTemporaryDirectory（）附加到它。
除此之外，我还向苹果填写了一份错误报告，但他们还没有回复。
在所有其他应用中，NSUrlSession的恢复是否已被破坏？可以在应用方面修复吗？
答案 0 :(得分：37)
这个问题来自于currentRequest和originalRequest NSKeyArchived编码的异常根“NSKeyedArchiveRootObjectKey”而不是NSKeyedArchiveRootObjectKey常量，它是字面上的“root”和NSURL（Mutable）请求的编码过程中的一些其他错误行为。
我在测试版1中检测到并提交了一个错误（第27144153号，以防您需要重复）。甚至我发送了一封电子邮件给NSURLSession团队支持人员的“Quinn the Eskimo”（eskimo1 at apple dot com），以确认他们收到了这封邮件，他说他们得到了这个并且知道问题。
更新：我终于找到了解决此问题的方法。将数据提供给correctResumeData（）函数，它将返回可用的恢复数据
更新2：您可以使用NSURLSession.correctedDownloadTaskWithResumeData（）/ URLSession.correctedDownloadTask（withResumeData :)函数来获取具有正确originalRequest和currentRequest变量的任务
更新3： Quinn说这个问题已在iOS 10.2中得到解决，您可以继续使用此代码与iOS 10.0和10.1兼容，它可以在没有任何问题的情况下使用新版本。
（对于Swift 3代码，请在下面滚动，对于Objective C，请参阅leavesstar post，但我没有对其进行测试）
Swift 2.3：
func correctRequestData(data: NSData?) -> NSData? {
guard let data = data else {
return nil
}
// return the same data if it's correct
if NSKeyedUnarchiver.unarchiveObjectWithData(data) != nil {
return data
}
guard let archive = (try? NSPropertyListSerialization.propertyListWithData(data, options: [.MutableContainersAndLeaves], format: nil)) as? NSMutableDictionary else {
return nil
}
// Rectify weird __nsurlrequest_proto_props objects to $number pattern
var k = 0
while archive["$objects"]?[1].objectForKey("$\(k)") != nil {
k += 1
}
var i = 0
while archive["$objects"]?[1].objectForKey("__nsurlrequest_proto_prop_obj_\(i)") != nil {
let arr = archive["$objects"] as? NSMutableArray
if let dic = arr?[1] as? NSMutableDictionary, let obj = dic["__nsurlrequest_proto_prop_obj_\(i)"] {
dic.setObject(obj, forKey: "$\(i + k)")
dic.removeObjectForKey("__nsurlrequest_proto_prop_obj_\(i)")
arr?[1] = dic
archive["$objects"] = arr
}
i += 1
}
if archive["$objects"]?[1].objectForKey("__nsurlrequest_proto_props") != nil {
let arr = archive["$objects"] as? NSMutableArray
if let dic = arr?[1] as? NSMutableDictionary, let obj = dic["__nsurlrequest_proto_props"] {
dic.setObject(obj, forKey: "$\(i + k)")
dic.removeObjectForKey("__nsurlrequest_proto_props")
arr?[1] = dic
archive["$objects"] = arr
}
}
// Rectify weird "NSKeyedArchiveRootObjectKey" top key to NSKeyedArchiveRootObjectKey = "root"
if archive["$top"]?.objectForKey("NSKeyedArchiveRootObjectKey") != nil {
archive["$top"]?.setObject(archive["$top"]?["NSKeyedArchiveRootObjectKey"], forKey: NSKeyedArchiveRootObjectKey)
archive["$top"]?.removeObjectForKey("NSKeyedArchiveRootObjectKey")
}
// Reencode archived object
let result = try? NSPropertyListSerialization.dataWithPropertyList(archive, format: NSPropertyListFormat.BinaryFormat_v1_0, options: NSPropertyListWriteOptions())
return result
}
func getResumeDictionary(data: NSData) -> NSMutableDictionary? {
var iresumeDictionary: NSMutableDictionary? = nil
// In beta versions, resumeData is NSKeyedArchive encoded instead of plist
if #available(iOS 10.0, OSX 10.12, *) {
var root : AnyObject? = nil
let keyedUnarchiver = NSKeyedUnarchiver(forReadingWithData: data)
do {
root = try keyedUnarchiver.decodeTopLevelObjectForKey("NSKeyedArchiveRootObjectKey") ?? nil
if root == nil {
root = try keyedUnarchiver.decodeTopLevelObjectForKey(NSKeyedArchiveRootObjectKey)
}
} catch {}
keyedUnarchiver.finishDecoding()
iresumeDictionary = root as? NSMutableDictionary
}
if iresumeDictionary == nil {
do {
iresumeDictionary = try NSPropertyListSerialization.propertyListWithData(data, options: [.MutableContainersAndLeaves], format: nil) as? NSMutableDictionary;
} catch {}
}
return iresumeDictionary
}
func correctResumeData(data: NSData?) -> NSData? {
let kResumeCurrentRequest = "NSURLSessionResumeCurrentRequest"
let kResumeOriginalRequest = "NSURLSessionResumeOriginalRequest"
guard let data = data, let resumeDictionary = getResumeDictionary(data) else {
return nil
}
resumeDictionary[kResumeCurrentRequest] = correctRequestData(resumeDictionary[kResumeCurrentRequest] as? NSData)
resumeDictionary[kResumeOriginalRequest] = correctRequestData(resumeDictionary[kResumeOriginalRequest] as? NSData)
let result = try? NSPropertyListSerialization.dataWithPropertyList(resumeDictionary, format: NSPropertyListFormat.XMLFormat_v1_0, options: NSPropertyListWriteOptions())
return result
}
extension NSURLSession {
func correctedDownloadTaskWithResumeData(resumeData: NSData) -> NSURLSessionDownloadTask {
let kResumeCurrentRequest = "NSURLSessionResumeCurrentRequest"
let kResumeOriginalRequest = "NSURLSessionResumeOriginalRequest"
let cData = correctResumeData(resumeData) ?? resumeData
let task = self.downloadTaskWithResumeData(cData)
// a compensation for inability to set task requests in CFNetwork.
// While you still get -[NSKeyedUnarchiver initForReadingWithData:]: data is NULL error,
// this section will set them to real objects
if let resumeDic = getResumeDictionary(cData) {
if task.originalRequest == nil, let originalReqData = resumeDic[kResumeOriginalRequest] as? NSData, let originalRequest = NSKeyedUnarchiver.unarchiveObjectWithData(originalReqData) as? NSURLRequest {
task.setValue(originalRequest, forKey: "originalRequest")
}
if task.currentRequest == nil, let currentReqData = resumeDic[kResumeCurrentRequest] as? NSData, let currentRequest = NSKeyedUnarchiver.unarchiveObjectWithData(currentReqData) as? NSURLRequest {
task.setValue(currentRequest, forKey: "currentRequest")
}
}
return task
}
}
斯威夫特3：
func correct(requestData data: Data?) -> Data? {
guard let data = data else {
return nil
}
if NSKeyedUnarchiver.unarchiveObject(with: data) != nil {
return data
}
guard let archive = (try? PropertyListSerialization.propertyList(from: data, options: [.mutableContainersAndLeaves], format: nil)) as? NSMutableDictionary else {
return nil
}
// Rectify weird __nsurlrequest_proto_props objects to $number pattern
var k = 0
while ((archive["$objects"] as? NSArray)?[1] as? NSDictionary)?.object(forKey: "$\(k)") != nil {
k += 1
}
var i = 0
while ((archive["$objects"] as? NSArray)?[1] as? NSDictionary)?.object(forKey: "__nsurlrequest_proto_prop_obj_\(i)") != nil {
let arr = archive["$objects"] as? NSMutableArray
if let dic = arr?[1] as? NSMutableDictionary, let obj = dic["__nsurlrequest_proto_prop_obj_\(i)"] {
dic.setObject(obj, forKey: "$\(i + k)" as NSString)
dic.removeObject(forKey: "__nsurlrequest_proto_prop_obj_\(i)")
arr?[1] = dic
archive["$objects"] = arr
}
i += 1
}
if ((archive["$objects"] as? NSArray)?[1] as? NSDictionary)?.object(forKey: "__nsurlrequest_proto_props") != nil {
let arr = archive["$objects"] as? NSMutableArray
if let dic = arr?[1] as? NSMutableDictionary, let obj = dic["__nsurlrequest_proto_props"] {
dic.setObject(obj, forKey: "$\(i + k)" as NSString)
dic.removeObject(forKey: "__nsurlrequest_proto_props")
arr?[1] = dic
archive["$objects"] = arr
}
}
/* I think we have no reason to keep this section in effect
for item in (archive["$objects"] as? NSMutableArray) ?? [] {
if let cls = item as? NSMutableDictionary, cls["$classname"] as? NSString == "NSURLRequest" {
cls["$classname"] = NSString(string: "NSMutableURLRequest")
(cls["$classes"] as? NSMutableArray)?.insert(NSString(string: "NSMutableURLRequest"), at: 0)
}
}*/
// Rectify weird "NSKeyedArchiveRootObjectKey" top key to NSKeyedArchiveRootObjectKey = "root"
if let obj = (archive["$top"] as? NSMutableDictionary)?.object(forKey: "NSKeyedArchiveRootObjectKey") as AnyObject? {
(archive["$top"] as? NSMutableDictionary)?.setObject(obj, forKey: NSKeyedArchiveRootObjectKey as NSString)
(archive["$top"] as? NSMutableDictionary)?.removeObject(forKey: "NSKeyedArchiveRootObjectKey")
}
// Reencode archived object
let result = try? PropertyListSerialization.data(fromPropertyList: archive, format: PropertyListSerialization.PropertyListFormat.binary, options: PropertyListSerialization.WriteOptions())
return result
}
func getResumeDictionary(_ data: Data) -> NSMutableDictionary? {
// In beta versions, resumeData is NSKeyedArchive encoded instead of plist
var iresumeDictionary: NSMutableDictionary? = nil
if #available(iOS 10.0, OSX 10.12, *) {
var root : AnyObject? = nil
let keyedUnarchiver = NSKeyedUnarchiver(forReadingWith: data)
do {
root = try keyedUnarchiver.decodeTopLevelObject(forKey: "NSKeyedArchiveRootObjectKey") ?? nil
if root == nil {
root = try keyedUnarchiver.decodeTopLevelObject(forKey: NSKeyedArchiveRootObjectKey)
}
} catch {}
keyedUnarchiver.finishDecoding()
iresumeDictionary = root as? NSMutableDictionary
}
if iresumeDictionary == nil {
do {
iresumeDictionary = try PropertyListSerialization.propertyList(from: data, options: PropertyListSerialization.ReadOptions(), format: nil) as? NSMutableDictionary;
} catch {}
}
return iresumeDictionary
}
func correctResumeData(_ data: Data?) -> Data? {
let kResumeCurrentRequest = "NSURLSessionResumeCurrentRequest"
let kResumeOriginalRequest = "NSURLSessionResumeOriginalRequest"
guard let data = data, let resumeDictionary = getResumeDictionary(data) else {
return nil
}
resumeDictionary[kResumeCurrentRequest] = correct(requestData: resumeDictionary[kResumeCurrentRequest] as? Data)
resumeDictionary[kResumeOriginalRequest] = correct(requestData: resumeDictionary[kResumeOriginalRequest] as? Data)
let result = try? PropertyListSerialization.data(fromPropertyList: resumeDictionary, format: PropertyListSerialization.PropertyListFormat.xml, options: PropertyListSerialization.WriteOptions())
return result
}
extension URLSession {
func correctedDownloadTask(withResumeData resumeData: Data) -> URLSessionDownloadTask {
let kResumeCurrentRequest = "NSURLSessionResumeCurrentRequest"
let kResumeOriginalRequest = "NSURLSessionResumeOriginalRequest"
let cData = correctResumeData(resumeData) ?? resumeData
let task = self.downloadTask(withResumeData: cData)
// a compensation for inability to set task requests in CFNetwork.
// While you still get -[NSKeyedUnarchiver initForReadingWithData:]: data is NULL error,
// this section will set them to real objects
if let resumeDic = getResumeDictionary(cData) {
if task.originalRequest == nil, let originalReqData = resumeDic[kResumeOriginalRequest] as? Data, let originalRequest = NSKeyedUnarchiver.unarchiveObject(with: originalReqData) as? NSURLRequest {
task.setValue(originalRequest, forKey: "originalRequest")
}
if task.currentRequest == nil, let currentReqData = resumeDic[kResumeCurrentRequest] as? Data, let currentRequest = NSKeyedUnarchiver.unarchiveObject(with: currentReqData) as? NSURLRequest {
task.setValue(currentRequest, forKey: "currentRequest")
}
}
return task
}
}
答案 1 :(得分：5)
关于unsupported URL错误和网络上的resumeData丢失或其他失败问题的部分问题，我已经记录了Apple的TSI以及Quinn的最新回复：
首先，您所看到的行为绝对是一个错误 NSURLSession。我们希望在未来的软件中解决这个问题 更新。正在跟踪这项工作。一世 没有任何信息可以分享修复程序何时发送到正常状态 iOS用户。
至于解决方法，我昨天和我现在详细讨论了这个问题 完全明白失败。 IMO有一种合理的工作方式 围绕这个，但我需要通过NSURLSession工程运行我的想法 在我分享之前。我希望在下一次听到他们的回复 一两天。请等待。
我会在发生更新时发布更新，但我确信这给了人们一些希望，至少苹果正在考虑这个问题。
（用于暂停/恢复行为的Mousavian解决方法的大量道具）
更新：
来自奎因，
事实上。自从我们上次谈话以来（我很抱歉，我已经花了这么长时间才回到你这里;我最近被埋葬在事件中）我代表其他一些开发人员进一步挖掘了这一点并发现： 答：此问题表现在两个上下文中，其特征是NSURLErrorCannotWriteToFile和NSURLErrorUnsupportedURL错误。 B.我们可以解决第一个问题但不是第二个问题。 我附上了我的文档的更新，填写了详细信息。 不幸的是，我们无法找到第二种症状的解决方法。前进的唯一方法是让iOS Engineering修复该bug。我们希望这将在iOS 10软件更新中发生，但我没有任何具体的细节可以分享（除了这个修复看起来它错过了10.1总线） - ：
所以，遗憾的是，unsupported URL问题没有解决，我们必须等待修复错误。
NSURLErrorCannotWriteToFile问题由上面的Mousavian代码处理。
另一个更新：
Quinn确认了最新的10.2测试版试图解决这些问题。
这是否可以查看10.2？
是。此问题的修复程序包含在第一个10.2测试版中。一个 我曾与之合作的开发人员数量已经报告了这个补丁 已经卡住了，但我仍然建议你自己尝试一下 最新测试版（目前为iOS 10.2 beta 2,14C5069c）。如果你，请告诉我 遇到任何障碍。
答案 2 :(得分：1)
这是Mousavian答案的Objective-C代码。
在iOS 9.3.5（设备）和iOS 10.1（模拟器）中工作正常。
首先以穆萨维的方式纠正恢复数据
- (NSData *)correctRequestData:(NSData *)data
{
if (!data) {
return nil;
}
if ([NSKeyedUnarchiver unarchiveObjectWithData:data]) {
return data;
}
NSMutableDictionary *archive = [NSPropertyListSerialization propertyListWithData:data options:NSPropertyListMutableContainersAndLeaves format:nil error:nil];
if (!archive) {
return nil;
}
int k = 0;
while ([[archive[@"$objects"] objectAtIndex:1] objectForKey:[NSString stringWithFormat:@"$%d", k]]) {
k += 1;
}
int i = 0;
while ([[archive[@"$objects"] objectAtIndex:1] objectForKey:[NSString stringWithFormat:@"__nsurlrequest_proto_prop_obj_%d", i]]) {
NSMutableArray *arr = archive[@"$objects"];
NSMutableDictionary *dic = [arr objectAtIndex:1];
id obj;
if (dic) {
obj = [dic objectForKey:[NSString stringWithFormat:@"__nsurlrequest_proto_prop_obj_%d", i]];
if (obj) {
[dic setObject:obj forKey:[NSString stringWithFormat:@"$%d",i + k]];
[dic removeObjectForKey:[NSString stringWithFormat:@"__nsurlrequest_proto_prop_obj_%d", i]];
arr[1] = dic;
archive[@"$objects"] = arr;
}
}
i += 1;
}
if ([[archive[@"$objects"] objectAtIndex:1] objectForKey:@"__nsurlrequest_proto_props"]) {
NSMutableArray *arr = archive[@"$objects"];
NSMutableDictionary *dic = [arr objectAtIndex:1];
if (dic) {
id obj;
obj = [dic objectForKey:@"__nsurlrequest_proto_props"];
if (obj) {
[dic setObject:obj forKey:[NSString stringWithFormat:@"$%d",i + k]];
[dic removeObjectForKey:@"__nsurlrequest_proto_props"];
arr[1] = dic;
archive[@"$objects"] = arr;
}
}
}
id obj = [archive[@"$top"] objectForKey:@"NSKeyedArchiveRootObjectKey"];
if (obj) {
[archive[@"$top"] setObject:obj forKey:NSKeyedArchiveRootObjectKey];
[archive[@"$top"] removeObjectForKey:@"NSKeyedArchiveRootObjectKey"];
}
NSData *result = [NSPropertyListSerialization dataWithPropertyList:archive format:NSPropertyListBinaryFormat_v1_0 options:0 error:nil];
return result;
}
- (NSMutableDictionary *)getResumDictionary:(NSData *)data
{
NSMutableDictionary *iresumeDictionary;
if ([[NSProcessInfo processInfo] operatingSystemVersion].majorVersion >= 10) {
NSMutableDictionary *root;
NSKeyedUnarchiver *keyedUnarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
NSError *error = nil;
root = [keyedUnarchiver decodeTopLevelObjectForKey:@"NSKeyedArchiveRootObjectKey" error:&error];
if (!root) {
root = [keyedUnarchiver decodeTopLevelObjectForKey:NSKeyedArchiveRootObjectKey error:&error];
}
[keyedUnarchiver finishDecoding];
iresumeDictionary = root;
}
if (!iresumeDictionary) {
iresumeDictionary = [NSPropertyListSerialization propertyListWithData:data options:0 format:nil error:nil];
}
return iresumeDictionary;
}
static NSString * kResumeCurrentRequest = @"NSURLSessionResumeCurrentRequest";
static NSString * kResumeOriginalRequest = @"NSURLSessionResumeOriginalRequest";
- (NSData *)correctResumData:(NSData *)data
{
NSMutableDictionary *resumeDictionary = [self getResumDictionary:data];
if (!data || !resumeDictionary) {
return nil;
}
resumeDictionary[kResumeCurrentRequest] = [self correctRequestData:[resumeDictionary objectForKey:kResumeCurrentRequest]];
resumeDictionary[kResumeOriginalRequest] = [self correctRequestData:[resumeDictionary objectForKey:kResumeOriginalRequest]];
NSData *result = [NSPropertyListSerialization dataWithPropertyList:resumeDictionary format:NSPropertyListXMLFormat_v1_0 options:0 error:nil];
return result;
}
我没有为NSURLSession创建一个类别，我只是在My Singleton中创建。 这是创建NSURLSessionDownloadTask的代码：
NSData *cData = [self correctResumData:self.resumeData];
if (!cData) {
cData = self.resumeData;
}
self.downloadTask = [self.session downloadTaskWithResumeData:cData];
if ([self getResumDictionary:cData]) {
NSDictionary *dict = [self getResumDictionary:cData];
if (!self.downloadTask.originalRequest) {
NSData *originalData = dict[kResumeOriginalRequest];
[self.downloadTask setValue:[NSKeyedUnarchiver unarchiveObjectWithData:originalData] forKey:@"originalRequest"];
}
if (!self.downloadTask.currentRequest) {
NSData *currentData = dict[kResumeCurrentRequest];
[self.downloadTask setValue:[NSKeyedUnarchiver unarchiveObjectWithData:currentData] forKey:@"currentRequest"];
}
}