从 Cocoa 向 Tumblr 发送 POST 请求

Question

此代码片段不起作用，我收到“身份验证失败”消息。来自服务器的响应。有什么想法吗？

    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] 
                                    initWithURL:
                                    [NSURL URLWithString:@"http://www.tumblr.com/api/write"]];
    [request setHTTPMethod:@"POST"];
    [request addValue:_tumblrLogin forHTTPHeaderField:@"email"];
    [request addValue:_tumblrPassword forHTTPHeaderField:@"password"];
    [request addValue:@"regular" forHTTPHeaderField:@"type"];
    [request addValue:@"theTitle" forHTTPHeaderField:@"title"];
    [request addValue:@"theBody" forHTTPHeaderField:@"body"];

    NSLog(@"Tumblr Login:%@\nTumblr Password:%@", _tumblrLogin, _tumblrPassword);

    [NSURLConnection connectionWithRequest:request delegate:self];

    [request release];

_tumblrLogin 和 _tumblrPassword 都通过代码中其他地方的 stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding 运行。我的登录电子邮件的格式为“[电子邮件受保护]”。它对于直接登录 tumblr 来说效果很好，但我想知道“+”字符是否会导致编码问题？这并没有被逃脱。应该是吗？

---

感谢 Martin 的建议，我现在使用 CFURLCreateStringByAddingPercentEscapes 来转义我的登录名和密码。不过，我仍然遇到同样的问题，我的身份验证失败。

Answer 1

问题是您没有创建正确的 HTTP POST 请求。 POST 请求需要格式正确的多部分 MIME 编码正文，其中包含要发送到服务器的所有参数。您尝试将参数设置为 HTTP 标头，但这根本不起作用。

此代码将执行您想要的操作，特别注意创建有效的多部分 MIME 字符串的 NSString 类别：

@interface NSString (MIMEAdditions)
+ (NSString*)MIMEBoundary;
+ (NSString*)multipartMIMEStringWithDictionary:(NSDictionary*)dict;
@end

@implementation NSString (MIMEAdditions)
//this returns a unique boundary which is used in constructing the multipart MIME body of the POST request
+ (NSString*)MIMEBoundary
{
    static NSString* MIMEBoundary = nil;
    if(!MIMEBoundary)
        MIMEBoundary = [[NSString alloc] initWithFormat:@"----_=_YourAppNameNoSpaces_%@_=_----",[[NSProcessInfo processInfo] globallyUniqueString]];
    return MIMEBoundary;
}
//this create a correctly structured multipart MIME body for the POST request from a dictionary
+ (NSString*)multipartMIMEStringWithDictionary:(NSDictionary*)dict 
{
    NSMutableString* result = [NSMutableString string];
    for (NSString* key in dict)
    {
        [result appendFormat:@"--%@\r\nContent-Disposition: form-data; name=\"%@\"\r\n\r\n%@\r\n",[NSString MIMEBoundary],key,[dict objectForKey:key]];
    }
    [result appendFormat:@"\r\n--%@--\r\n",[NSString MIMEBoundary]];
    return result;
}
@end


@implementation YourObject
- (void)postToTumblr
{
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] 
                                    initWithURL:
                                    [NSURL URLWithString:@"http://www.tumblr.com/api/write"]];
    [request setHTTPMethod:@"POST"];
    //tell the server to expect 8-bit encoded content as we're sending UTF-8 data, 
    //and UTF-8 is an 8-bit encoding
    [request addValue:@"8bit" forHTTPHeaderField:@"Content-Transfer-Encoding"];
    //set the content-type header to multipart MIME
    [request addValue: [NSString stringWithFormat:@"multipart/form-data; boundary=%@",[NSString MIMEBoundary]] forHTTPHeaderField: @"Content-Type"];

    //create a dictionary for all the fields you want to send in the POST request
    NSDictionary* postData = [NSDictionary dictionaryWithObjectsAndKeys:
                                 _tumblrLogin, @"email",
                                 _tumblrPassword, @"password",
                                 @"regular", @"type",
                                 @"theTitle", @"title",
                                 @"theBody", @"body",
                                 nil];
    //set the body of the POST request to the multipart MIME encoded dictionary
    [request setHTTPBody: [[NSString multipartMIMEStringWithDictionary: postData] dataUsingEncoding: NSUTF8StringEncoding]];
    NSLog(@"Tumblr Login:%@\nTumblr Password:%@", _tumblrLogin, _tumblrPassword);
    [NSURLConnection connectionWithRequest:request delegate:self];
    [request release];
}
@end

Answer 2

根据此问题的答案，stringByAddingPercentEscapesUsingEncoding: 不执行完整的转义编码。但是，无论出于何种原因，此方法的 CoreFoundation 版本都会这样做：

[(NSString *) CFURLCreateStringByAddingPercentEscapes(NULL, 
    (CFStringRef)[[self mutableCopy] autorelease], NULL, 
    CFSTR("=,!
amp;'()*+;@?\n\"<>#\t :/"), kCFStringEncodingUTF8) autorelease];

您还可以使用 NSMutableString 的replaceOccurencesOfString:withString:options: 方法手动进行替换，但该方法更加重复和冗长。 （请参阅此处。）