我有一个应用程序，当它通过-[AppDelegate application:didReceiveRemoteNotification:fetchCompletionHandler:]. 推送有效负载包含一个我需要预取的 url，以便在下一次应用程序启动时准备好数据。
该应用程序需要completionHandler在下载完成时调用：
下载操作完成时要执行的块。调用此块时，传入最能描述下载操作结果的获取结果值。您必须调用此处理程序并且应该尽快这样做。有关可能值的列表，请参阅 UIBackgroundFetchResult 类型。
问题是我是否可以做一个简单的请求，或者我是否应该使用此处描述NSURLSession的后台提取之一进行提取
选项1：使用简单NSURLSession并调用回调
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result))completionHandler
{
NSURL *url = [NSURL URLWithString:userInfo[@"my-data-url"]];
NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
NSURLSessionDataTask *task = [session dataTaskWithRequest:[NSURLRequest requestWithURL:url] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
// save the result & call the
completionHandler(data ? UIBackgroundFetchResultNewData : UIBackgroundFetchResultNoData);
}];
[task resume];
}
选项 2：使用额外的后台处理来下载内容
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result))completionHandler
{
NSURLSessionDataTask *task;
__block UIBackgroundTaskIdentifier backgroundId = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
// time's up, cancel the download
[application endBackgroundTask:backgroundId];
backgroundId = UIBackgroundTaskInvalid;
completionHandler(UIBackgroundFetchResultFailed);
[task cancel];
}];
NSURL *url = [NSURL URLWithString:userInfo[@"my-data-url"]];
NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
task = [session dataTaskWithRequest:[NSURLRequest requestWithURL:url] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
// check if time was up
if(backgroundId == UIBackgroundTaskInvalid) {
return;
}
[application endBackgroundTask:backgroundId];
backgroundId = UIBackgroundTaskInvalid;
// save the result & call the
completionHandler(data ? UIBackgroundFetchResultNewData : UIBackgroundFetchResultNoData);
}];
[task resume];
}