Sum duplicate on NSMutableArray

问题

I have a NSMutableArray with objects of type NSMutableDictionary,

the NSMutableDictionary contains 2 keys

-Airlines (string)

-Rating (integer)

I have an NSMutableArray with all the objects and what i need is to Sum the rating of all the airline companies repeated objects, an example:

Airline  Rating

  A         2

  B         3

  B         4

  C         5

The end result array will be the A = 2, C = 5 and the Sum of B´s that is equal to 7.

My code so far:

for (int i = 0; i < arrayMealRating.count; ++i) {
         NSMutableDictionary *item = [arrayMealRating objectAtIndex:i];
         NSLog(@"item=%@",item);
         for (int j = i+1; j < arrayMealRating.count; ++j)
         {
           if ([[item valueForKey:@"Airline"] isEqualToString:[arrayMealRating objectAtIndex:j]]){
                NSMutableDictionary *item = [arrayMealRating objectAtIndex:j];
                NSMutableDictionary *item1 = [arrayMealRating objectAtIndex:i];
                NSInteger auxCount =  [[item valueForKey:@"setMealRating"] integerValue] + [[item1 valueForKey:@"setMealRating"] integerValue];

                NSMutableDictionary *aux = [NSMutableDictionary dictionaryWithObjectsAndKeys:[item valueForKey:@"Airline"], @"Airline"
                                                        ,[NSString stringWithFormat:@"%d",auxCount], @"setMealRating"
                                                        ,nil];
                NSLog(@"aux=%@",aux);
                [arrayMealRating replaceObjectAtIndex:i withObject:aux];

            }
         }
   }

A bit messy i know but i dont know how to work with NSMutableDictionary, any help will be much appreciated, Thanks in Advance!

回答1:

Incase you dont want to change how your storing the data, heres how you would do it using key-value coding. Heres the dirrect link to the documentation for @distinctUnionOfObjects and @sum.

// Get all the airline names with no duplicates using the KVC @distinctUnionOfObjects collection operator
NSArray *airlineNames = [arrayMealRating valueForKeyPath:@"@distinctUnionOfObjects.Airline"];

// Loop through all the airlines
for (NSString *airline in airlineNames) {

    // Get an array of all the dictionaries for the current airline
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(Airline == %@)", airline];
    NSArray *airlineMealRating = [arrayMealRating filteredArrayUsingPredicate:predicate];

    // Get the sum of all the ratings using KVC @sum collection operator
    NSNumber *rating = [airlineMealRating valueForKeyPath:@"@sum.Rating"];
    NSLog(@"%@: %@", airline, rating);
}

This gives the following output

A: 2
B: 7
C: 5

回答2:

I would suggest to redesign that entirely if that's at all possible.

Create a class Airline

@interface Airline : NSObject

@property (strong, nonatomic) NSString *name;
@property (strong, nonatomic) NSMutableArray *mealRatings;

- (void)addMealRating:(float)rating;
- (float)sumOfMealRatings;

@end


@implementation

- (id)initWithName:(NSString *)pName
{
    self = [super init];
    if (self)
    {
        self.name = pName;
        self.mealRatings = [NSMutableArray array];
    }
    return self;
}

- (void)addMealRating:(float)rating
{
    [self.mealRatings addObject:@(rating)];
}

- (float)sumOfRatings
{
    float sum = 0;
    for (NSNumber *rating in self.mealRatings)
    {
        sum += [rating floatValue];
    }
 }

 @end

Then in your 'mainclass' you simply hold an NSArray with instances of your Airline objects. It might require you to change some of your existing code, but I think in the long run it saves you time and trouble. Perhaps you recognize later on, that you want to add additional properties to your Airlines. A dictionary is a cumbersome way to do that.

回答3:

@try this

NSMutableArray *myArray = [[NSMutableArray alloc] initWithCapacity:4];

NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
[dict setValue:[NSNumber numberWithInteger:2] forKey:@"A"];
[myArray addObject:dict];

NSMutableDictionary *dict2 = [[NSMutableDictionary alloc] init];
[dict2 setValue:[NSNumber numberWithInteger:3] forKey:@"B"];
[myArray addObject:dict2];

NSMutableDictionary *dict3 = [[NSMutableDictionary alloc] init];
[dict3 setValue:[NSNumber numberWithInteger:4] forKey:@"B"];
[myArray addObject:dict3];

NSMutableDictionary *dict4 = [[NSMutableDictionary alloc] init];
[dict4 setValue:[NSNumber numberWithInteger:5] forKey:@"D"];
[myArray addObject:dict4];


NSMutableDictionary *resultDictionary = [[NSMutableDictionary alloc] init];

for(NSMutableDictionary *dictionary in myArray)
{
    NSString *key = [[dictionary allKeys] objectAtIndex:0];

    NSInteger previousValue = [[resultDictionary objectForKey:key] integerValue];


        NSInteger value = [[dictionary objectForKey:key] integerValue];

        previousValue += value;



    [resultDictionary setObject:[NSNumber numberWithInteger:previousValue] forKey:key];

}

for(NSString *key in resultDictionary)
{
    NSLog(@"value for key = %@ = %d",key, [[resultDictionary valueForKey:key] integerValue]);
}

来源：https://stackoverflow.com/questions/13124857/sum-duplicate-on-nsmutablearray

标签

iphone

ios

nsmutablearray

nsmutabledictionary