更新： 找到解决方案。您可以在文章末尾阅读。

我正在尝试使用 对远程 REST API 执行 POST
请求NSURLSession。这个想法是使用两个参数发出请求：deviceId和textContent。

问题是服务器无法识别这些参数。服务器部分工作正常，因为我已经使用 POSTMAN for Google Chrome 发送了一个 POST
并且它工作得很好。

这是我现在正在使用的代码：

NSString *deviceID = [[NSUserDefaults standardUserDefaults] objectForKey:@"deviceID"];
NSString *textContent = @"New note";
NSString *noteDataString = [NSString stringWithFormat:@"deviceId=%@&textContent=%@", deviceID, textContent];

NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
sessionConfiguration.HTTPAdditionalHeaders = @{
                                               @"api-key"       : @"API_KEY",
                                               @"Content-Type"  : @"application/json"
                                               };
NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfiguration];
NSURL *url = [NSURL URLWithString:@"http://url_to_manage_post_requests"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
request.HTTPBody = [noteDataString dataUsingEncoding:NSUTF8StringEncoding];
request.HTTPMethod = @"POST";
NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    // The server answers with an error because it doesn't receive the params
}];
[postDataTask resume];

我已经尝试了相同的过程NSURLSessionUploadTask：

// ...
NSURL *url = [NSURL URLWithString:@"http://url_to_manage_post_requests"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
request.HTTPMethod = @"POST";
NSURLSessionUploadTask *uploadTask = [session uploadTaskWithRequest:request fromData:[noteDataString dataUsingEncoding:NSUTF8StringEncoding] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    // The server answers with an error because it doesn't receive the params
}];
[uploadTask resume];

有任何想法吗？

解决方案

我的方法的问题是我在Content-Type所有请求中都发送了不正确的标头。因此，代码正常工作所需的唯一更改是删除Content-Type = application/jsonHTTP 标头。所以正确的代码是这样的：

NSString *deviceID = [[NSUserDefaults standardUserDefaults] objectForKey:@"deviceID"];
NSString *textContent = @"New note";
NSString *noteDataString = [NSString stringWithFormat:@"deviceId=%@&textContent=%@", deviceID, textContent];

NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
sessionConfiguration.HTTPAdditionalHeaders = @{
                                               @"api-key"       : @"API_KEY"
                                               };
NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfiguration];
NSURL *url = [NSURL URLWithString:@"http://url_to_manage_post_requests"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
request.HTTPBody = [noteDataString dataUsingEncoding:NSUTF8StringEncoding];
request.HTTPMethod = @"POST";
NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    // The server answers with an error because it doesn't receive the params
}];
[postDataTask resume];

与其他参数一起发送图像

如果您需要使用NSURLSession此处发布图像以及其他参数，您有一个示例：

NSString *deviceID = [[NSUserDefaults standardUserDefaults] objectForKey:@"deviceID"];
NSString *textContent = @"This is a new note";

// Build the request body
NSString *boundary = @"SportuondoFormBoundary";
NSMutableData *body = [NSMutableData data];
// Body part for "deviceId" parameter. This is a string.
[body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"\r\n\r\n", @"deviceId"] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:@"%@\r\n", deviceID] dataUsingEncoding:NSUTF8StringEncoding]];
// Body part for "textContent" parameter. This is a string.
[body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"\r\n\r\n", @"textContent"] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:@"%@\r\n", textContent] dataUsingEncoding:NSUTF8StringEncoding]];
// Body part for the attachament. This is an image.
NSData *imageData = UIImageJPEGRepresentation([UIImage imageNamed:@"ranking"], 0.6);
if (imageData) {
    [body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"; filename=\"image.jpg\"\r\n", @"image"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[@"Content-Type: image/jpeg\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:imageData];
    [body appendData:[[NSString stringWithFormat:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
}
[body appendData:[[NSString stringWithFormat:@"--%@--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];

// Setup the session
NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
sessionConfiguration.HTTPAdditionalHeaders = @{
                                               @"api-key"       : @"55e76dc4bbae25b066cb",
                                               @"Accept"        : @"application/json",
                                               @"Content-Type"  : [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary]
                                               };

// Create the session
// We can use the delegate to track upload progress
NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfiguration delegate:self delegateQueue:nil];

// Data uploading task. We could use NSURLSessionUploadTask instead of NSURLSessionDataTask if we needed to support uploads in the background
NSURL *url = [NSURL URLWithString:@"URL_TO_UPLOAD_TO"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
request.HTTPMethod = @"POST";
request.HTTPBody = body;
NSURLSessionDataTask *uploadTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    // Process the response
}];
[uploadTask resume];