Change a dictionary's all value to string - ios

Question

I want to change the Dictionary's all value to String, how to do with it?
Such as:
{ #"a":"a",
#"b":2,
#"c":{
#"c1":3,
#"c2":4
}
}
I want convert to :
{ #"a":"a",
#"b":"2",
#"c":{
#"c1":"3",
#"c2":"4"
}
}
How to do with it? I think all the day.
If I use below method to traverse the dictionary values:
NSArray *valueList = [dictionary allValues];
for (NSString * value in valueList) {
// change the value to String
}
If the value is a dictionary, how about it?
So, someone can help with that?

Answer 1

You could do this with a recursive method, it changes all NSNumber values to NSString and calls itself for nested dictionaries. Since a dictionary cannot be mutated while being enumerated a new dictionary is created and populated:
- (void)changeValuesOf:(NSDictionary *)dictionary result:(NSMutableDictionary *)result
{
for (NSString *key in dictionary) {
id value = dictionary[key];
if ([value isKindOfClass: [NSDictionary class]]) {
NSMutableDictionary * subDict = [NSMutableDictionary dictionary];
result[key] = subDict;
[self changeValuesOf:value result:subDict];
} else if ([value isKindOfClass: [NSNumber class]]) {
result[key] = [NSString stringWithFormat:#"%#", value];
} else {
result[key] = value;
}
}
}
NSDictionary *dictionary = #{#"a": #"a", # "b":#2, #"c": #{#"c1": #3, #"c2":#4 }};
NSMutableDictionary *result = [NSMutableDictionary dictionary];
[self changeValuesOf:dictionary result:result];
NSLog(#"%#", result);

Answer 2

You can create category for a dictionary and add method some like stringValueForKey:.
The realisation can be something like this:
- (NSString)stringValueForKey:(NSString*)key
{
id value = self[key];
if( [value respondsToSelector:#selector(stringValue)])
return [value performSelector:#selector(stringValue)]
return nil;
}