Objective C: Create arrays from the first array based on a value
I have an array of comma separated strings like:
Steve Jobs,12,CA
Fake Name,21,CA
Test Name,22,CA
Bill Gates,44,WA
Bill Nye,21,OR
I have these values in an NSScanner object so that I can loop through the values and get each comma separated value using objectAtIndex.
So what I would like to do is group the elements of the array into new arrays based on value, in this case State. So from them I need to go through, check what state they are in, and insert them into a new array, one array for each state.
CA Array:
Steve Jobs,12,CA
Fake Name,21,CA
Test Name,22,CA
WA Array:
Bill Gates,44,WA
OR Array:
Bill Nye,21,OR
So in the end, I would have 3 new arrays, one for each state. Also, if there were additional states in the first array, they should create new arrays as well.
Any help would be appreciated!
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You can use NSMutableDictionary
of NSMutableArray
- if the detected state is not already in the dictionary, add a new array.
NSMutableArray* arr = [states objectForKey:state];
if (arr == nil) {
arr = [NSMutableArray array];
[states setObject:arr forKey:state];
}
You can then insert values into the array, preferably as objects, although Dave DeLong is mentioned.
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You don't have to support this data as CSV. It takes a world of pain if you ever need to manipulate that data programmatically (like what you are trying to do).
You can naively split this data into an array with NSArray * portions = [line componentsSeparatedByString:@","];
. Then create a custom object to hold each part (see this post for example ) and then you can manipulate those objects easily.
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Naively: (assuming an array of strings called strings)
NSMutableDictionary *states = [NSMutableDictionary dictionary];
for (NSString *string in strings) {
NSString *state = [[string componentsSeparatedByString:@", "] lastObject];
NSMutableArray *values = [states objectForKey:state];
if (values == nil) {
values = [NSMutableArray array];
[states setObject:value forKey:state];
}
[values addObject:string];
}
A few things about this - firstly, I'm not on my computer, so there is a high chance of typos and things I missed. Second, you probably want to adapt string-separated components for better whitespace management.
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