Path for key in NSDictionary - objective-c

Question

In my app I need to insert values into NSDictionary having only last path component. E.g. my given dict is
a = 1;
b = 2;
c = 3;
d = {
e = 4;
f = 5;
g = {
h = 6;
};
};
j = {
k = 7;
};
and I need to change value for k. Path components should be #[#"j", #"k"]. I tried it with something like that:
- (void)recurse:(NSDictionary*)dict keyToFound:(NSString*)ktf stack:(NSMutableArray*)stack parent:(NSString*)parent
{
for (NSString *key in [dict allKeys]) {
if ([key isEqualToString:ktf]) {
[stack insertObject:key atIndex:[stack count]];
return;
}
else {
if ([[dict valueForKey:key] isKindOfClass:[NSDictionary class]]) {
NSDictionary *d = [dict valueForKey:key];
[stack insertObject:key atIndex:[stack count]];
[self recurse:d keyToFound:ktf stack:stack parent:key];
//[stack removeObject:key];
}
}
}
}
but, obviuos, it's a wrong way.

Answer 1

Here are two simpler ways to set the value in nested dictionaries. The first assumes that you know that the keys exist and could be C identifiers. In this case using setValue:forKeyPath: is the best approach. Otherwise a simple loop in function (or a Method or a category on NSDictionary) will do the trick:
void setValueForPathComponentsOfDictionary(id value, NSArray *components, NSMutableDictionary *dict) {
NSMutableArray *parts = [components mutableCopy];
id lastPart = parts.lastObject;
[parts removeLastObject];
for (id part in parts) {
if (![dict respondsToSelector:#selector(objectForKey:)])
return; // Silently fail.
dict = [dict objectForKey:part];
}
if ([dict respondsToSelector:#selector(objectForKey:)])
[dict setValue:value forKey:lastPart];
}
int main (int argc, const char * argv[])
{
#autoreleasepool {
NSMutableDictionary *dict = [#{
#"a":[#{#"a":#1,#"b":#2} mutableCopy],
#"b":[#{#"a":#3,#"b":#4} mutableCopy]
} mutableCopy];
NSLog(#"Initial Dictionary: %#", dict);
[dict setValue:#9 forKeyPath:#"a.b"];
NSLog(#"After setValue:forKeyPath: %#", dict);
setValueForPathComponentsOfDictionary(#0, #[#"b",#"a"], dict);
NSLog(#"After setValueForPathComponentsOfDictionary %#", dict);
}
return 0;
}

Answer 2

Ok, I've found the solution.
- (BOOL)recurse:(NSDictionary*)dict keyToFound:(NSString*)ktf stack:(NSMutableArray*)stack parent:(NSString*)parent
{
BOOL result = NO;
for (NSString *key in [dict allKeys]) {
if ([key isEqualToString:ktf]) {
[stack insertObject:key atIndex:[stack count]];
return YES;
}
else {
if ([[dict valueForKey:key] isKindOfClass:[NSDictionary class]]) {
NSDictionary *d = [dict valueForKey:key];
[stack insertObject:key atIndex:[stack count]];
result = [self recurse:d keyToFound:ktf stack:stack parent:key];
if (!result) {
[stack removeLastObject];
}
}
}
}
return result;
}

Answer 3

NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithObjectsAndKeys:#1,#"a",
#1,#"b",
#2,#"c",
[NSMutableDictionary dictionaryWithObjectsAndKeys:#4, #"e",
#5, #"f",
[NSMutableDictionary dictionaryWithObject:#6 forKey:#"h"], #"g", nil],#"d",
[NSMutableDictionary dictionaryWithObject:#7 forKey:#"k"],#"i",nil];
NSLog(#"Before %#",dict);
NSString *keyToChange = #"e";
NSString *valueToChange = #"Your New Value";
[dict enumerateKeysAndObjectsUsingBlock:^(id key ,id obj, BOOL *stop){
if([key isEqualToString:keyToChange])
{
NSLog(#"Found : %#",keyToChange);
if(![obj isKindOfClass:[NSArray class]] || ![obj isKindOfClass:[NSDictionary class]] || ![obj isKindOfClass:[NSMutableDictionary class]])
{
[dict setValue:#"newval" forKey:keyToChange];
return;
}
}
if([obj isKindOfClass:[NSDictionary class]])
{
[obj enumerateKeysAndObjectsUsingBlock:^(id key ,id obj1, BOOL *stop){
if([key isEqualToString:keyToChange])
{
if(![obj isKindOfClass:[NSArray class]] || ![obj isKindOfClass:[NSDictionary class]] || ![obj isKindOfClass:[NSMutableDictionary class]])
{
NSLog(#"Found : %#",keyToChange);
[obj setValue:#"newval" forKey:keyToChange];
return;
}
}
}];
}
}];
NSLog(#"After %#",dict);