Sorting two NSMutableArrays [duplicate] - ios

Question

This question already has answers here:
Sorting two NSArrays together side by side
(4 answers)
Closed 7 years ago.
I'm trying to add fb friends scores table and I'm facing the problem by sorting them. From request, I'm getting two mutable arrays, one with friends name and one with their scores. Now I need to sort the scores in descending order (from highest to lowest). Sorting only scores is easy with this code:
NSSortDescriptor *scoreSorter= [[NSSortDescriptor alloc] initWithKey:#"self" ascending:NO];
[self.friendScoresArray sortUsingDescriptors:[NSArray arrayWithObject:scoreSorter]];
but if I do like this, I'm losing the connection between name and score, so I need to sort the names also now. Here's the example what happens now:
After request:
(Name - Score)
Name One - 110
Name Two - 120
Name Three - 100
After sorting the scores:
Name One - 120
Name Two - 110
Name Three - 100
This is obvious of course, but just a quick example of what I'm getting. Also, I've tried old method from C++ called bubble method. It's worked, but it's slow and sometimes giving ascending order, so that is bad practice in my opinion. So, what's the best way to sort out those to arrays without loosing connect between name and score? Thank you.

Answer 1

Pack each name and score into an object, stick that object into an array, sort that array based on the score member. I think this method should work quite well.

Answer 2

I would do something like this:
NSArray *_names = [NSArray arrayWithObjects:#"Jack", #"Zoe", #"Natalie", nil];
NSArray *_scores = [NSArray arrayWithObjects:#(110), #(120), #(100), nil];
NSMutableArray *_combined = [NSMutableArray array];
#define kName #"kName"
#define kScore #"kScore"
[_names enumerateObjectsUsingBlock:^(NSString * name, NSUInteger idx, BOOL *stop) {
NSNumber *_score = [_scores objectAtIndex:idx];
[_combined addObject:[NSDictionary dictionaryWithObjectsAndKeys:name, kName, _score, kScore, nil]];
}];
[_combined sortWithOptions:NSSortStable usingComparator:^NSComparisonResult(NSDictionary * obj1, NSDictionary * obj2) {
Float64 _score1 = [[obj1 valueForKey:kScore] doubleValue], _score2 = [[obj2 valueForKey:kScore] doubleValue];
if (_score1 < _score2) return NSOrderedDescending;
else return NSOrderedAscending;
}];
the input:
Jack - 110
Zoe - 120
Natalie - 100
the output:
Zoe - 120
Jack - 110
Natalie - 100

Answer 3

NSArray *first = [NSArray arrayWithObjects: #"quick", #"brown", #"fox", #"jumps", nil];
NSArray *second = [NSArray arrayWithObjects: #"jack", #"loves", #"my", #"sphinx", nil];
NSMutableArray *p = [NSMutableArray arrayWithCapacity:first.count];
for (NSUInteger i = 0 ; i != first.count ; i++) {
[p addObject:[NSNumber numberWithInteger:i]];
}
[p sortWithOptions:0 usingComparator:^NSComparisonResult(id obj1, id obj2) {
// Modify this to use [first objectAtIndex:[obj1 intValue]].name property
NSString *lhs = [first objectAtIndex:[obj1 intValue]];
// Same goes for the next line: use the name
NSString *rhs = [first objectAtIndex:[obj2 intValue]];
return [lhs compare:rhs];
}];
NSMutableArray *sortedFirst = [NSMutableArray arrayWithCapacity:first.count];
NSMutableArray *sortedSecond = [NSMutableArray arrayWithCapacity:first.count];
[p enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSUInteger pos = [obj intValue];
[sortedFirst addObject:[first objectAtIndex:pos]];
[sortedSecond addObject:[second objectAtIndex:pos]];
}];