如何处理Web服务的空响应

Question

My app consuming PHP web services. But some field of response is null and i cant handle that null value.

This is my response

[
{
ID: 1,
ChapterID: 0,
Code: "FLGSV01",
Number: "0",
Text: "Swedish Flag",
VersionChanged: 1,
LastChange: "Jun 26 2013 12:00:00:000AM",
Type: "img",
info: null
}
]

I have parsed this response in my dictionary which like this

tmpDictn : {
    ID = 1,
    ChapterID = 1;
    Code = SECH1W;
    ID = 2;
    LastChange = "Jun 26 2012 12:00:00:000AM";
    Number = 001;
    Text = "ett
\n";
    Type = img;
    VersionChanged = 1;
    info = "<null>";
}

Now as you see value for info is Null and if i try to parse it in string than my string will be <null> but instead of this i just want it to display empty string.

I have tried this code but no luck

if ([tmpDictn objectForKey:@"info"]!=nil) {
            info = [tmpDictn objectForKey:@"info"];
        }

And this code gives me error of NSNull

if ([[tmpDictn objectForKey:@"info"] isEqualToString:@"<null>"]) {
            info = [tmpDictn objectForKey:@"info"];
        }

So how could i handle this null value?

Answer 1

Compare with [NSNull null]

From Docs

The NSNull class defines a singleton object used to represent null values in collection objects (which don't allow nil values).

if([tmpDictn objectForKey:@"info"] == [NSNull null]) 
{
  info = nil;
}
else
{
  info = [tmpDictn objectForKey:@"info"]
}

Answer 2

info = [tmpDictn objectForKey:@"info"];
if(info == null)
{
    //Handle null
}

Answer 3

if ([[tmpDictn objectForKey:@"info"] isKindOfClass:[NSNull class]])
{
    info = [tmpDictn objectForKey:@"info"];
}

Answer 4

Try to use [NSNull null]

if ([tmpDictn objectForKey:@"info"]!=[NSNull null]) {
      info = [tmpDictn objectForKey:@"info"];
} else {
      //Handle null value
}