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iOS

Sorting an array based on attributes of an object

Hello all, I am trying to sort an NSMutableArray based on an NSUInteger attribute named baseRankNumber which is a part of the homeworkItem class. Here is the code, I don't understand what is wrong about it. Thank you!

    homeworkObject* homeworkItem = source.homeworkItem;
    NSUInteger* arrayLen = (NSUInteger*)[self.homeworkObjectItem count];

    for (NSUInteger* i = 0; i <arrayLen; i++) {

        homeworkObject* localHomeworkItem = [self.homeworkObjectItem objectAtIndex:*i];

        if (homeworkItem.baseRankNumber>localHomeworkItem.baseRankNumber) {


            [self.homeworkObjectItem replaceObjectAtIndex:*i withObject:homeworkItem];

        }

        i++;
    }

3 Answers

Thomas Nilsen
Thomas Nilsen
14,957 Points

I think NSSortDiscriptor would be the right approach here. http://nshipster.com/nssortdescriptor/

Thank you Thomas!

Okay so I tried to sort the baseRankNumber proper of the homeworkItem object like this. Please note that delegate is the name of the appDelegate instance and not an actual delegate

NSSortDescriptor* baseRankDescriptor = [[NSSortDescriptor alloc] initWithKey:@"baseRankNumber" ascending:YES];

    NSArray *sortDescriptors = @[baseRankDescriptor];

    NSArray* sortedHomeworkItems = [self.delegate.homeworkItemsArray sortedArrayUsingDescriptors:sortDescriptors];

    [self.delegate.homeworkItemsArray removeAllObjects];

    [self.delegate.homeworkItemsArray arrayByAddingObjectsFromArray:sortedHomeworkItems];