我一直在使用cURL我的iOS应用程序下载大约1700+个文件 - 总共大约~290MB.我的Internet连接大约需要5-7分钟才能下载所有这些内容cURL.但由于不是每个人都有快速的互联网连接(特别是在旅途中),我决定允许在后台下载文件,以便用户在等待下载完成时可以做其他事情.这是NSURLSession进来的地方.
使用时NSURLSession,我的互联网连接需要大约20多分钟才能在应用程序处于前台时下载所有这些内容.当应用程序处于后台时,我不介意它很慢,因为我知道由操作系统来安排下载.但即使它在前景中它很慢也是一个问题.这是预期的行为吗？是因为文件的数量？
如果我没有NSURLSession正确使用,这里有一个我如何使用它的片段:
// Initialization
NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:@"<my-identifier>"];
sessionConfiguration.HTTPMaximumConnectionsPerHost = 40;
backgroundSession = [NSURLSession sessionWithConfiguration:sessionConfiguration
delegate:self
delegateQueue:nil];
// ...
// Creating the tasks and starting the download
for (int i = 0; i < 20 && queuedRequests.count > 0; i++) {
NSDictionary *requestInfo = [queuedRequests lastObject];
NSURLSessionDownloadTask *downloadTask = [backgroundSession downloadTaskWithURL:[NSURL URLWithString:requestInfo[@"url"]]];
ongoingRequests[@(downloadTask.taskIdentifier)] = requestInfo;
[downloadTask resume];
[queuedRequests removeLastObject];
NSLog(@"Begin download file %d/%d: %@", …我有一个元组:
std::tuple<int, std::string, bool> foo = { 10, "Hello, world!", false };
我有一个类型的单个变量:
MyClass bar;
我应该如何编写一个将一个值(或者甚至多个值,如果可能的话)附加到一个新元组中的泛型函数？
std::tuple<int, std::string, bool, MyClass> fooBar = tuple_append(foo, bar);
^^^^^^^^^^^^
// I need this magical function!
我正在尝试使用ios-cmake生成针对iOS的Xcode项目.但是,它找不到Threads.这是一个简单的CMake脚本用于演示:
CMAKE_MINIMUM_REQUIRED (VERSION 2.8)
PROJECT (MyCITest)
SET (CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake/modules")
########################
# EDIT: I've also tried adding the lines below prior to posting this question,
# but there doesn't seem to be any effect.
# (http://stackoverflow.com/questions/8386897)
SET (CMAKE_REQUIRED_INCLUDES ${CMAKE_IOS_SDK_ROOT}/usr ${CMAKE_IOS_SDK_ROOT}/usr/include)
SET (CMAKE_CXX_FLAGS "--sysroot=${CMAKE_IOS_SDK_ROOT} ${CMAKE_CXX_FLAGS}")
SET (CMAKE_C_FLAGS "--sysroot=${CMAKE_IOS_SDK_ROOT} ${CMAKE_C_FLAGS}")
########################
FIND_PACKAGE (ZLIB REQUIRED)
FIND_PACKAGE (LibXml2 REQUIRED)
FIND_PACKAGE (Threads REQUIRED)
从终端运行CMake:
cmake .. -DCMAKE_TOOLCHAIN_FILE=../cmake/toolchains/iOS.cmake -GXcode
这是我得到的输出:
-- Toolchain using default iOS SDK: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.0.sdk
-- Found ZLIB: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.0.sdk/usr/lib/libz.dylib (found version "1.2.5")
-- …