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# Comparator

Defines the signature for a block object used for comparison operations.

```
typealias Comparator = (Any, Any) -> ComparisonResult
```

## Discussion

The arguments to the [Block object](https://developer.apple.com/library/archive/documentation/General/Conceptual/DevPedia-CocoaCore/Block.html#//apple_ref/doc/uid/TP40008195-CH3) are two objects to compare. The block returns an [`ComparisonResult`](/documentation/Foundation/ComparisonResult) value to denote the ordering of the two objects.

You use `NSComparator` blocks in comparison operations such as `NSArray`’s [`sortedArray(comparator:)`](/documentation/Foundation/NSArray/sortedArray(comparator:)), for example:

```objc
NSArray *sortedArray = [array sortedArrayUsingComparator: ^(id obj1, id obj2) {
 
    if ([obj1 integerValue] > [obj2 integerValue]) {
        return (NSComparisonResult)NSOrderedDescending;
    }
 
    if ([obj1 integerValue] < [obj2 integerValue]) {
        return (NSComparisonResult)NSOrderedAscending;
    }
    return (NSComparisonResult)NSOrderedSame;
}];
```

---

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