How to use NSComparator?

问题:

I would like to know if the below question is possible using NSComparator or not?

I have two arrays; both hold data models. I have a property named rank in the data model. Now I want to compare both arrays and want to know if one of them holds higher ranked data models. If Yes I would like to get NSComparisonResult = NSOrderedAscending.

By the way I'm using another approach here: is "total of each data Model's rank in array and if the total is greater than second array's data Model's total rank."

回答1:

Yes, it would look something like this:

NSArray *someArray = /* however you get an array */    
NSArray *sortedArray = [someArray sortedArrayUsingComparator:^(id obj1, id obj2) {
  NSNumber *rank1 = [obj1 valueForKeyPath:@"@sum.rank"];
  NSNumber *rank2 = [obj2 valueForKeyPath:@"@sum.rank"];
  return (NSComparisonResult)[rank1 compare:rank2];
}];

(updated to show actually using the comparator)