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：

[objc] view
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<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

[objc] view
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<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