Resort is a small library that builds comparators from key paths, combines separate comparators into compound ones, and can build reverse comparators.
Sorting from a keyPath would be a very straightforward thing to do, if
it weren't for the edge cases. This library deals with nil and NSNull
values and offers special handling of those, like always-less and
always-greater comparison. It uses always-less as a pragmatic
default. But if that's not what you need you can specify that nil
should always be treated as greater. Or you might want to fail fast
and throw an exception.
Order is defined for the classes in Foundation that support it already
via compare: methods: NSString, NSDate, NSNumber,
NSIndexPath, as well as their subclasses, e.g. NSMutableString and
NSDecimalNumber.
In other cases, the comparator just performs the ordering on the
-description of the object.
Comparators build from key paths are very similar to NSSortDescriptors, but the have the advantage to be easy to combine. This is what the other half of the library is about, compound comparators. Think of it as a simple, composable way to define a sort order with primary, secondary, and so on sort keys.
To run the example project; clone the repo, and run pod install from
the Example directory first.
Creation and use of a keyPath comparator looks like this:
NSComparator comparator = [RESResort comparatorForKeyPath:@"name"];
NSArray *sorted = [@[ z, a ] sortedArrayUsingComparator:comparator];Two comparators (keyPath based or otherwise) can be combined into a compound comparator and used like this:
NSComparator nameComparator = [RESResort comparatorForKeyPath:@"name"];
NSComparator countComparator = [RESResort comparatorForKeyPath:@"count"];
NSComparator compoundComparator = [RESResort compoundComparatorWithComparatorArray:@[ nameComparator, countComparator ]];
NSArray *sorted = [_array sortedArrayUsingComparator:compoundComparator];Only Foundation framework. Tested on iOS 7 and OS X 10.9.
Florian Ebeling, florian.ebeling@gmail.com
Resort is available under the MIT license. See the LICENSE file for more info.