CRASH: -[NSNull length]: unrecognized selector sent to instance错误的处理办法

开发中从后台请求数据，返回如下：

2014-12-05 16:44:52.535 掌麦[6984:613] getDefaultAddress: reuslt == {
    item =     {
        data =         {
            address = "<null>";
            area = "<null>";
            city = "<null>";
            name = "";
            phone = 18503051318;
            province = "<null>";
        };
        mark = 1;
        msg = "\U6210\U529f";
    };
    status = 1;
}

我直接解析出字典dic，赋值：

 <span style="font-size:18px;">    NSString *address = [dic objectForKey:@"address"];
     //NSString *area = [dic objectForKey:@"area"];
     NSString *name = [dic objectForKey:@"name"];
     //NSString *city = [dic objectForKey:@"city"];
     NSString *phone = [dic objectForKey:@"phone"];
     //NSString *province = [dic objectForKey:@"province"];
     self.addressLabel.text = address;
     self.nameLabel.text    = name;
     self.phoneLabel.text   = phone;

 </span>

   结果报错：CRASH: -[NSNull length]: unrecognized selector sent to instance

原因及时后台返回有些值为null，在object－c中就是nsull的空值

所以解析后，应加一判断，防止出错

 <span style="font-size:18px;">    if (![address isKindOfClass:[NSNull class]]) {
         self.addressLabel.text = address;
     }
     if (![name isKindOfClass:[NSNull class]]) {
         self.nameLabel.text    = name;
     }
     if (![phone isKindOfClass:[NSNull class]]) {
         self.phoneLabel.text   = phone;
     }
 </span>

这样就OK了

转载：http://blog.csdn.net/feixiang_song/article/details/41749679