如何在iPhone SDK中将文件上传到服务器？

// 1. 创建服务器URL
NSURL *serverURL = [NSURL URLWithString:@"http://example.com/upload"];

// 2. 读取要上传的文件
NSString *filePath = [[NSBundle mainBundle] pathForResource:@"example" ofType:@"txt"];
NSData *fileData = [NSData dataWithContentsOfFile:filePath];

// 3. 创建请求对象
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:serverURL];
[request setHTTPMethod:@"POST"];

// 4. 设置请求头部信息
[request setValue:@"text/plain" forHTTPHeaderField:@"Content-Type"];
[request setValue:[NSString stringWithFormat:@"%lu", (unsigned long)[fileData length]] forHTTPHeaderField:@"Content-Length"];

// 5. 设置请求体
[request setHTTPBody:fileData];

// 6. 发送请求
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[connection start];