解析 JSON 显示 nil 值

Question

SBJsonParser *parser = [[SBJsonParser alloc] init];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.krsconnect.no/community/api.html?method=bareListEventsByCategory&appid=620&category-selected=350&counties-selected=Vest-Agder,Aust-Agder"]];
NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *json_string = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
NSDictionary *object = [parser objectWithString:json_string error:nil];
//appDelegate.books = [[NSMutableArray alloc] initWithCapacity:0];
appDelegate.books1 = [[NSMutableArray alloc] init];

NSArray *results = [parser objectWithString:json_string error:nil];
for (int i=0; i<[results count]; i++) {
    Book1  *aBook = [[Book1 alloc] initWithDictionary:[results objectAtIndex:i]];
    [appDelegate.books1 addObject:aBook];
    Book1 *mybook=[appDelegate.books1 objectAtIndex:i];
    NSString*test=mybook.location;
    NSLog(test);
}

字典解析

- (id)initWithDictionary:(NSDictionary*) dict {

    self.date = [dict valueForKey:@"date"];
    self.location =  [dict valueForKey:@"location"];
    self.municipality = [dict valueForKey:@"municipality"];
    self.title =  [dict valueForKey:@"title"];

    return self;
}

Answer 1

NSDictionary *object = [parser objectWithString:json_string error:nil]; 
.. 
NSArray *results = [parser objectWithString:json_string error:nil];

这一次，您可能需要决定要解析的数据应该是 NSArray 还是 NSDictionary（见上文：您将相同的字符串分配给它们中的任何一个）。

一般来说：您的数据错误（很可能格式不正确），这是 SBJson 返回 nil 的最可能原因，但是，将 NSError 传递给错误参数可能会给您提供真正的原因（这就是错误处理的真正用途）