NSURLSession 简介

NSURLSessionDataTask // 普通任务
NSURLSessionDownLoadTask // 文件下载任务
NSURLSessionUploadTask // 文件上传任务

NSURLSession 实现 GET 请求

- (IBAction)login {
//判断账号与密码是否为空
NSString *name = _accountText.text;
if (name == nil || name.length == 0){
NSLog(@"请输入账号");
return;
}

NSString *pwd = _pwdText.text;
if (pwd == nil || pwd.length == 0){
NSLog(@"请输入密码");
return;
}

//创建URL
NSString *urlStr = [NSString stringWithFormat:@"http://localhost:8080/Server/login?username=%@&pwd=%@", name, pwd];

//用NSURLSession实现登录
[self sessionWithUrl:urlStr];
}

- (void)sessionWithUrl:(NSString *)urlStr{
NSURL *url = [NSURL URLWithString:urlStr];

//用NSURLConnection实现登录
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
request.HTTPMethod = @"GET";

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
if (data == nil || error != nil) {
NSLog(@"请求失败");
return;
}

//JSON解析
NSError *error2;
NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:&error2];
if (error2) {
NSLog(@"解析失败 -- %@", error2);
}
NSLog(@"数据为 -- %@", dict);
}];
[task resume];

}

NSURLSession 实现 POST 请求:

- (IBAction)login {
//判断账号与密码是否为空
NSString *name = _accountText.text;
if (name == nil || name.length == 0){
NSLog(@"请输入账号");
return;
}

NSString *pwd = _pwdText.text;
if (pwd == nil || pwd.length == 0){
NSLog(@"请输入密码");
return;
}

//用NSURLSession实现登录
//创建URL
NSString *urlStr = @"http://localhost:8080/Server/login";
[self sessionWithUrl:urlStr];
}

- (void)sessionWithUrl:(NSString *)urlStr{
NSURL *url = [NSURL URLWithString:urlStr];

//用NSURLConnection实现登录
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
//POST请求
request.HTTPMethod = @"POST";
NSString *prama = [NSString stringWithFormat:@"username=%@&pwd=%@", _accountText.text, _pwdText.text];
//中文转码
[prama stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
//转码
request.HTTPBody = [prama dataUsingEncoding:NSUTF8StringEncoding];

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
if (data == nil || error != nil) {
NSLog(@"请求失败");
return;
}

//JSON解析
NSError *error2;
NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:&error2];
if (error2) {
NSLog(@"解析失败 -- %@", error2);
}
NSLog(@"数据为 -- %@", dict);
}];
[task resume];

}

NSURLSession 实现 断点续传:

//断点下载
@property (nonatomic, strong) NSURLSession *session;
@property (nonatomic, strong) NSURLSessionDownloadTask *task;
@property (nonatomic, strong) NSData *resumeData;
@property (weak, nonatomic) IBOutlet UIProgressView *progressView;

//懒加载
- (NSURLSession *)session{
if (!_session) {
NSURLSessionConfiguration *cfg = [NSURLSessionConfiguration defaultSessionConfiguration];
_session = [NSURLSession sessionWithConfiguration:cfg delegate:self delegateQueue:[NSOperationQueue mainQueue]];
}
return _session;
}

/**
*  NSURLSession实现断点下载
*/
- (IBAction)startDowbLoad:(id)sender {
NSURL *url = [NSURL URLWithString:@"http://localhost:8080/Server/resources/videos/minion_01.mp4"];
self.task = [self.session downloadTaskWithURL:url];
//开始下载
[self.task resume];
}

/**
*  暂停下载
*/
- (IBAction)pauseDownLoad:(id)sender{
__weak typeof (self) vc = self;
/**
*  @param resumeData 包含了继续下载开始的位置和下载的URL
*/
[self.task cancelByProducingResumeData:^(NSData * _Nullable resumeData) {
vc.resumeData = resumeData;
self.task = nil;
}];
}

/**
*  恢复下载
*/
- (IBAction)resumeDownLoad:(id)sender {
//传入上次下载的数据
self.task = [self.session downloadTaskWithResumeData:self.resumeData];
//开始下载
[self.task resume];
//清空
self.resumeData = nil;
}

#pragma mark - NSURLSessionDelegate 代理方法
//下载完成调用
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location{
//下载完成后,写入 caches 文件中
NSString *cachesFile = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:downloadTask.response.suggestedFilename];

NSFileManager *mgr = [NSFileManager defaultManager];
[mgr moveItemAtPath:location.path toPath:cachesFile error:nil];
}

/**
*  下载过程中调用这个方法, 每当下载完(写完)一部分时会调用, (可能被调用多次)
*
*  @param bytesWritten              这次写了多少
*  @param totalBytesWritten         累计写了多少
*  @param totalBytesExpectedToWrite 文件的总长度
*/
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite{
self.progressView.progress = (double)totalBytesWritten / totalBytesExpectedToWrite;
}

//恢复下载的时候调用
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didResumeAtOffset:(int64_t)fileOffset expectedTotalBytes:(int64_t)expectedTotalBytes{

}