IOS post请求? 400 报错

相当于是通过 POST 方法传递参数，在下面地址里有很多 iOS 的 HTTP 编程方面的文章，找一下，有的：）

http://www.oschina.net/ios/264/ios-http

//NSDictionary的key要和post提交的变量名相对应
- (NSString *)post:(NSString *)postUrl withData:(NSMutableDictionary *)postData {
	NSURL *url = [NSURL URLWithString:postUrl];
	ASIFormDataRequest *request=[ASIFormDataRequest requestWithURL:url];
	NSEnumerator *enumerator = [postData keyEnumerator];
	id key;
	while (key = [enumerator nextObject]) {
		//检查是否要上传文件
		if ([key isEqual:UPLOAD_FILES_DICT]) {
			NSDictionary *uploadFiles = [postData objectForKey:key];
			if ([uploadFiles count] > 0) {
				for (id k in uploadFiles) {
					NSString *fileName = [uploadFiles objectForKey:k];
					if ([[NSFileManager defaultManager] fileExistsAtPath:fileName]) {
						[request setFile:fileName forKey:k];
					}
				}
			}
		} else {
			[request setPostValue:[postData objectForKey:key] forKey:key];
		}
	}
	
	//设置30s超时
	[request setTimeOutSeconds:30];
	[request startSynchronous];
	int httpStatusCode = [request responseStatusCode];
	NSString *response = @"";
	if (httpStatusCode < 400 && httpStatusCode > 100) {
		response = [request responseString];
		NSLog(@"Ret:%@", response);
	}
	return response;
}