从JSON字典中获取正确的类型值

Question

is there a way in objectivec to get exact value type from a json dictionary?

For example, consider this json:

{
    "ret": 0,
    "state": "Italy",
    "lat": 45.46347,
    "lon": 9.19404
}

I want to get INT value for " ret ", NSString value for " state ", and FLOAT value for " lat " and " lon ".

I'm using this snippet:

NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:@"sampleJson.json"]];
NSDictionary *dict = [ NSJSONSerialization JSONObjectWithData:data options:0 error:nil ];

id val = [ dict valueForKeyPath:@"lat" ][0];

NSLog(@"%@", [val class] );

but obviously, the output is a generic NSNumber .

2014-01-31 11:13:51.903 Test0002[2044:70b] __NSCFNumber

It's possible to get a float instead of NSNumber , automatically?

Answer 1

To check if the NSNumber is float or int, you can use this method:

    if ([val isMemberOfClass:[NSNumber class]])
    {
        switch(CFNumberGetType((CFNumberRef((NSNumber)val))
        {
          /* List of results:
          kCFNumberSInt8Type
         kCFNumberSInt16Type
         kCFNumberSInt32Type
         kCFNumberSInt64Type
         kCFNumberFloat32Type
         kCFNumberFloat64Type
         kCFNumberCharType
         etc... */
        }
    }

Once you found the type, just use:

float f = [((NSNumber)val) floatValue];

or

int i =[((NSNumber)val) intValue];

Find the whole list here:

CFNumber Ref

To check that it's a NSString, just do:

if([val isMemberOfClass:[NSString class]])
{
}