iOS中使用NSURLSession上传字符串

#pragma mark -POST上传字符串-

//urlStr：服务器地址     parmater：传递的参数
-(void)sendPost1:(NSString *)urlStr parmater:(NSString *)parm{

NSURL *url = [NSURL URLWithString:urlStr];
//创建可变的请求
NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url];

//设定请求方式
[request setHTTPMethod:@"POST"];

//要上传的数据转化成二进制data类型
NSData *postData = [parm dataUsingEncoding:NSUTF8StringEncoding];

//设置请求体
[request setHTTPBody:postData];

//设置请求长度
[request setValue:[NSString stringWithFormat:@"%lu",(unsigned long)postData.length] forHTTPHeaderField:@"Content-Length"];

//设置上传数据的格式
[request addValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];

//创建会话
NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionUploadTask *task = [session uploadTaskWithRequest:request fromData:postData completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
if (!error && data) {
/*数据下载完成，在此处写下载完成后执行的代码块*/
}else{
NSLog(@"error:%@",error);
}
}];
[task resume];
}