PHP to JSON to iPhone

可能重复：
无法获取ASIHTTPRequest回调委托以触发

我有一个php文件，它输出以下JSON:

[{"0":"5","questionId":"5","1":"Morning Heart Rate","question":"Morning Heart Rate","2":"5","questionNumber":"5","3":"1","sectionId":"1"},{"0":"4","questionId":"4","1":"Evening Urine Colour","question":"Evening Urine Colour","2":"4","questionNumber":"4","3":"1","sectionId":"1"},{"0":"3","questionId":"3","1":"Evening Bodyweight","question":"Evening Bodyweight","2":"3","questionNumber":"3","3":"1","sectionId":"1"},{"0":"2","questionId":"2","1":"Morning Urine Colour","question":"Morning Urine Colour","2":"2","questionNumber":"2","3":"1","sectionId":"1"},{"0":"1","questionId":"1","1":"Morning Bodyweight","question":"Morning Bodyweight","2":"1","questionNumber":"1","3":"1","sectionId":"1"},{"0":"6","questionId":"6","1":"Time of Month (TOM)","question":"Time of Month (TOM)","2":"6","questionNumber":"6","3":"1","sectionId":"1"}]

这可以在以下链接中看到：

http://dev.speechlink.co.uk/David/get_questionstest.php

我在Objective C中使用JSONKit作为解码JSON的框架。以下方法用于与php通信：

//方法

+(void)getQuestions:(NSString*)sectionId{
    NSString* url = @"http://dev.speechlink.co.uk/David/get_questions.php";
    NSURL *link = [NSURL URLWithString:url];
    ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:link]; 
    [request setPostValue:sectionId forKey:@"section"]; 
    [request setDelegate:self];
    [request setDidFinishSelector:@selector(requestFinished:)];
    [request startAsynchronous];    
}
- (void)requestFinished:(ASIHTTPRequest *)request
{
    //NSString *response = [request responseString];
    NSLog(@"hello"); //never prints
}

从未调用委托。。。有人能解释一下吗？