Category on NSDictionary that will convert string values to numbers or vice versa. Useful for JSON deserialization.

NSDictionary+XXXConvertValues.h

#import <Foundation/Foundation.h>

@interface NSDictionary (XXXConvertValues)

// Return value associated wth key, converted to NSString
- (NSString *) stringValueForKey:(id)key;

// Return integer value associated with key, converted to integer
- (NSInteger) integerValueForKey:(id)key;

// Return double value associated with key, converted to double
- (double) doubleValueForKey:(id)key;

@end

NSDictionary+XXXConvertValues.m

#import "NSDictionary+XXXConvertValues.h"

@implementation NSDictionary (XXXConvertValues)

- (NSString *) stringValueForKey:(id)key {
    id obj = [self objectForKey:key];
    if ([obj isKindOfClass:[NSString class]]) {
        return obj;
    }
    else if ([obj isKindOfClass:[NSNumber class]]) {
        return [obj stringValue];
    }
    else {
        return [obj description];
    }
}

- (NSInteger) integerValueForKey:(id)key {
    id obj = [self objectForKey:key];
    if ([obj respondsToSelector:@selector(integerValue)]) {
        return [obj integerValue];
    }
    else {
        return 0;
    }
}

- (double) doubleValueForKey:(id)key {
    id obj = [self objectForKey:key];
    if ([obj respondsToSelector:@selector(doubleValue)]) {
        return [obj doubleValue];
    }
    else {
        return 0;
    }
}

@end