I am playing with a variety of JSON frameworks in Objective-C. All are severely under-documented but then, they are simple to use, right? No. Nonetheless, I am deeply in awe and in debt to the great individuals who invested endless hours of their time to build these libraries and give them to us to use free of charge. Thanks you.
Anyway, SBJSON from Stig Brautaset, which I am examining right now, exposed a relatively weird issue. How do you test for null values in the contents of the parsed NSDictionary at hand?
Plain old ([dictionary valueForKey:@"key"] == null) will not work. The breakthrough came when looking at the dictionary printout to gdb (Right-click the object in memory and select 'Print Description to Console'). The null value was 'stored' in a CFNull reference. To test whether a pointer is pointing at CFNull, you do this:
myVariable == kCFNull where kCFNull is a special memory address dedicated to hold this special null (nil!) value.
2 replies on “SBJSON: Testing for nil / NULL value”
Thanks buddy. You helped me….:)
The catch is that, it requires me to check for all the variable I get out of parsing..
IS there any alternative?
Frankly I am not sure there is. At best try to iterate over the response elements.
Not much consolation, I know :-/