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Question

NSString *urlString =[NSString stringWithFormat:@"http://api.stackoverflow.com/1.0/questions?tagged=iphone & key=%d",key1];
    NSURL *url = [NSURL URLWithString:urlString];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
                                                           cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
    [request setHTTPMethod:@"POST"];
    [request setValue:@"text/json" forHTTPHeaderField:@"Content-Type"];
    [request setValue:@"text/json" forHTTPHeaderField:@"Accept"];

    NSError        *error ;
    NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:&error];
    NSString *json_string = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
    NSLog(@"jsondata=%@,%@",json_string,response);

2011-02-11 12:01:16.653 mystack[1946:207] jsondata=,(null)

Answer 1

Your URL string is not valid since it contains blank spaces: & . You need to escape those before creating an NSURL object. Replace:

NSString *urlString =[NSString stringWithFormat:@"http://api.stackoverflow.com/1.0/questions?tagged=iphone & key=%d",key1];

with:

NSString *urlString =[NSString stringWithFormat:@"http://api.stackoverflow.com/1.0/questions?tagged=iphone & key=%d",key1];
urlString = [urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

Answer 2

thanks for helping me here is the answer

[request setHTTPMethod:@"POST"];
    [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    [request setValue:@"application/json" forHTTPHeaderField:@"Accept"];

the code that i have to change..

Answer 3

您应该使用NSLog您的错误变量来查看发生了什么： [error localizedDescription]