在OS X 10.9配置WebDAV服务器联合NSURLSessionUploadTask实现文件上传
iOS7推出的NSURLSession简化了NSURLConnection的文件上传和下载的工作，本文记录如何配置WebDAV服务以支持PUT方式的文件上传。
一. 配置WebDAV服务器
1. 修改httpd.conf
1> 打开终端，依次输入：
cd /etc/apache2/
sudo vi httpd.conf
2> 在vi中输入
查找httpd-dav.conf
3> 将该行最前面的 # 注释删除
4> 保存并退出
输入
2. 修改httpd-dav.conf
1> 在终端中依次输入：
cd /etc/apache2/extra
sudo vi httpd-dav.conf
2> 按照以下内容修改httpd-dav.conf中的内容
提示：仅修改了授权类型和用户密码文件两个位置
DavLockDB "/usr/var/DavLock"

Alias /uploads "/usr/uploads"

<directory "="" usr="" uploads"="">
     Dav On

     Order Allow,Deny
     Allow from all

     #用户的授权类型
     AuthType Basic
     AuthName DAV-upload

     # You can use the htdigest program to create the password database:
     # htdigest -c "/usr/user.passwd" DAV-upload admin
     # 用户密码文件
     AuthUserFile "/usr/webdav.passwd"
     AuthDigestProvider file

     # Allow universal read-access, but writes are restricted
     
      require user admin
     

说明：
按照上述配置文件，可以通过URL->http://localhost/uploads，将文件上传至/usr/uploads目录
上传文件所使用的用户名是：admin
3> 保存并退出
输入
3. 建立文件夹并配置文件
1> 创建admin的密码，在终端中输入：
sudo htpasswd -c /usr/webdav.passwd admin
然后输入admin的密码，密码文件会保存在/usr/webdav.passwd中
2> 设置webdav.passwd权限
sudo chgrp www /usr/webdav.passwd
3> 建立var文件夹，以保存DavLockDB相关文件
sudo mkdir -p /usr/var
sudo chown -R www:www /usr/var
4> 建立上传文件夹：uploads
sudo mkdir -p /usr/uploads
sudo chown -R www:www /usr/uploads
5> 重新启动Apache
sudo apachectl -k restart
4. 测试
打开Finder，在菜单中选择“前往"“连接服务器"，在地址栏中输入：http://localhost/uploads
然后用户名admin及在终端设置的密码，连接至服务器，并测试更新文件。
二. 使用NSURLSessionUploadTask实现文件上传
- (IBAction)uploadFile
{
     // 要上传的文件
     UIImage *image = [UIImage imageNamed:@"123.jpg"];
     NSData *imageData = UIImageJPEGRepresentation(image, 1.0f);

     // 上传的文件名
     NSString *urlString = @"http://localhost/uploads/demo.jpg";
     urlString = [urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

     NSURL *url = [NSURL URLWithString:urlString];
     NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:url];
     // 使用PUT方法
     [request setHTTPMethod: @"PUT"];

     // 用户授权
     NSString *basicAuthCredentials = [NSString stringWithFormat:@"%@:%@", @"admin", @"123"];
     NSString *authValue = [NSString stringWithFormat:@"Basic %@", AFBase64EncodedStringFromString(basicAuthCredentials)];
     [request setValue:authValue forHTTPHeaderField:@"Authorization"];

     [request setHTTPBody: imageData];
     [request setValue:@"image/jpg" forHTTPHeaderField:@"Content-Type"];
     [request setValue:[NSString stringWithFormat:@"%d", [imageData length]] forHTTPHeaderField:@"Content-Length"];

     // URLSession
     NSURLSession *session = [NSURLSession sharedSession];
     // 上传任务
     NSURLSessionUploadTask *task = [session uploadTaskWithRequest:request fromData:imageData completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
      
      if (!data) {
           NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
           NSLog(@"%@ %@", result, response);
      } else {
           NSLog(@"upload ok!");
      }
     }];

     [task resume];
}
另外，还需要一个对字符串进行Base64编码的方法，代码如下：
static NSString *AFBase64EncodedStringFromString(NSString *string)
{
     NSData *data = [NSData dataWithBytes:[string UTF8String] length:[string lengthOfBytesUsingEncoding:NSUTF8StringEncoding]];
     NSUInteger length = [data length];
     NSMutableData *mutableData = [NSMutableData dataWithLength:((length + 2) / 3) * 4];

     uint8_t *input = (uint8_t *)[data bytes];
     uint8_t *output = (uint8_t *)[mutableData mutableBytes];

     for (NSUInteger i = 0; i < length; i += 3) {
      NSUInteger value = 0;
      for (NSUInteger j = i; j < (i + 3); j++) {
           value <<= 8;
           if (j < length) {
                value |= (0xFF & input[j]);
           }
      }
      
      static uint8_t const kAFBase64EncodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
      
      NSUInteger idx = (i / 3) * 4;
      output[idx + 0] = kAFBase64EncodingTable[(value >> 18) & 0x3F];
      output[idx + 1] = kAFBase64EncodingTable[(value >> 12) & 0x3F];
      output[idx + 2] = (i + 1) < length ? kAFBase64EncodingTable[(value >> 6) & 0x3F] : ‘=‘;
      output[idx + 3] = (i + 2) < length ? kAFBase64EncodingTable[(value >> 0) & 0x3F] : ‘=‘;
     }

     return [[NSString alloc] initWithData:mutableData encoding:NSASCIIStringEncoding];
}