NSURLSession基本使用

NSURLSession

使用步骤

创建NSURLSession

创建Task

执行Task

NSURLSessionDataTask

GET

NSURL *url = [NSURL URLWithString:@"http://124.25.226.186:32812/login?username=baoduit&pwd=baiduit"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];

// 1.获得NSURLSession对象
NSURLSession *session = [NSURLSession sharedSession];

// 2.创建任务
NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSLog(@"%@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
}];

// 3.启动任务
[task resume];

NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/login?username=baoduit&pwd=baoduit"];
// 1.获得NSURLSession对象
NSURLSession *session = [NSURLSession sharedSession];

// 2.创建任务
NSURLSessionDataTask *task = [session dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSLog(@"%@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
}];
// 3.启动任务
[task resume];

POST

NSURL *url = [NSURL URLWithString:@"http://123.25.226.186:32812/login"];
// 设置请求头
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
request.HTTPMethod = @"POST";
request.HTTPBody = [@"username=520it&pwd=520it" dataUsingEncoding:NSUTF8StringEncoding];

// 1.获得NSURLSession对象
NSURLSession *session = [NSURLSession sharedSession];

// 2.创建任务
NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSLog(@"%@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
}];
// 3.启动任务
[task resume];

NSURLSessionDataDelegate代理注意事项

Task都是通过Session监听

// 1.获得NSURLSession对象
NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];

+ NSURLSessionDataDelegate`默认不会接受数据`

/**
* 1.接收到服务器的响应
*/
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler
{
NSLog(@"%s", __func__);
NSLog(@"%@", [NSThread currentThread]);
/*
NSURLSessionResponseAllow: 去向处理服务器响应, 内部会调用[task cancle]
NSURLSessionResponseCancel: 允许处理服务器的响应，才会继续接收服务器返回的数据
NSURLSessionResponseBecomeDownload: 讲解当前请求变为下载
*/
completionHandler(NSURLSessionResponseAllow);
}
/**
* 2.接收到服务器的数据（可能会被调用多次）
*/
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data
{
NSLog(@"%s", __func__);
}
/**
* 3.请求成功或者失败（如果失败，error有值）
*/
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
{
NSLog(@"%s", __func__);
}

NSURLSessionDownloadTask

DownloadTask默认已经实现边下载边写入

// 1.创建request
NSURL *url = [NSURL URLWithString:@"http://123.25.226.186:32812/resources/videos/minion_01.mp4"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];

// 2.创建session
NSURLSession *session = [NSURLSession sharedSession];

// 3.创建下载任务
NSURLSessionDownloadTask *task = [session downloadTaskWithRequest:request completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
NSLog(@"%@", location.absoluteString);

NSFileManager *manager = [NSFileManager defaultManager];
NSString *toPath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
toPath = [toPath stringByAppendingPathComponent:response.suggestedFilename];
// 将下载好的文件从location移动到cache
[manager moveItemAtURL:location toURL:[NSURL fileURLWithPath:toPath] error:nil];
}];

// 4.开启下载任务
[task resume];

DownloadTask断点下载

暂停: suspend

继续: resume

取消: cancel

任务一旦被取消就无法恢复

区别并返回下载信息

//取消并获取当前下载信息
[self.task cancelByProducingResumeData:^(NSData *resumeData) {
self.resumeData = resumeData;
}];

// 根据用户上次的下载信息重新创建任务
self.task = [self.session downloadTaskWithResumeData:self.resumeData];
[self.task resume];

DownloadTask监听下载进度

/**
* 每当写入数据到临时文件时，就会调用一次这个方法
* totalBytesExpectedToWrite:总大小
* totalBytesWritten: 已经写入的大小
* bytesWritten: 这次写入多少
*/
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
{
NSLog(@"正在下载: %.2f", 1.0 * totalBytesWritten / totalBytesExpectedToWrite);
}

/*
* 根据resumeData恢复任务时调用
* expectedTotalBytes:总大小
* fileOffset: 已经写入的大小
*/
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didResumeAtOffset:(int64_t)fileOffset expectedTotalBytes:(int64_t)expectedTotalBytes
{
NSLog(@"didResumeAtOffset fileOffset = %lld , expectedTotalBytes = %lld", fileOffset, expectedTotalBytes);
}
/**
* 下载完毕就会调用一次这个方法
*/
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location
{
NSLog(@"下载完毕");
// 文件将来存放的真实路径
NSString *file = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:downloadTask.response.suggestedFilename];

// 剪切location的临时文件到真实路径
NSFileManager *mgr = [NSFileManager defaultManager];
[mgr moveItemAtURL:location toURL:[NSURL fileURLWithPath:file] error:nil];
}
/**
* 任务完成
*/
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
{
NSLog(@"didCompleteWithError");
}

离线断点下载

使用NSURLSessionDataTask

NSMutableURLRequest *reuqest = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"]];
// 核心方法, 实现从指定位置开始下载
NSInteger currentBytes = KCurrentBytes;
NSString *range = [NSString stringWithFormat:@"bytes=%zd-", currentBytes];
[reuqest setValue:range forHTTPHeaderField:@"Range"];

// 核心方法, 自己实现边下载边写入
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data;

NSURLSessionUploadTask

设置设置请求头, 告诉服务器是文件上传

multipart/form-data; boundary=lnj

必须自己

严格按照格式

拼接请求体

请求体不能设置给request, 只能设置给fromData

The body stream and body data in this request object are ignored.

+

[[self.session uploadTaskWithRequest:request fromData:body completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSLog(@"%@", [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil]);
}] resume];

注意:以下方法用于PUT请求

[self.session uploadTaskWithRequest:<#(nonnull NSURLRequest *)#> fromFile:<#(nonnull NSURL *)#>]