Sort string contains numbers, NSMutableArray with Dictionaries - ios

Question

strings like
"4 Miles 400 stones"
"2 Miles 10 stones"
"6 Miles 2 Stones"
a key value of dictionary in NsMutableArray, I am trying to sort them by the amount of miles then stones.
regular sortUsingDescriptor :
[list sortUsingDescriptors:[NSArray arrayWithObjects:[NSSortDescriptor sortDescriptorWithKey:#"systems" ascending:YES], nil]];
or NSNumericSearch :
NSMutableArray *newList;
NSArray *result = [list sortedArrayUsingFunction:&sort context:#"systems"];
newList= [[NSMutableArray alloc] initWithArray:result];
NSInteger sort(id a, id b, void* p) {
return [[a valueForKey:(__bridge NSString*)p]
compare:[b valueForKey:(__bridge NSString*)p]
options:NSNumericSearch];
}
are not working.
Do I have to parse the string get numbers then sort it? or is there an easier way to sort this?

Answer 1

Here is how to do it the best, object-oriented way.
First. Create a class. Let's call it MyObject:
#interface MyObject : NSObject
#property(nonatomic, assign) NSUInteger miles;
#property(nonatomic, assign) NSUInteger stones;
+ (MyObject *)objectWithString:(NSString *)string;
#end
As you can see, it has a objectWithString that we will use to create objects using information in a string like: "4 Miles 400 stones".
#implementation MyObject
+ (MyObject *)objectWithString:(NSString *)string
{
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"[0-9]+?(?= Miles | stones)" options:0 error:nil];
NSArray *matches = [regex matchesInString:string options:0 range:NSMakeRange(0, [string length])];
MyObject *myObject = [[MyObject alloc] init];
myObject.miles = [[string substringWithRange:((NSTextCheckingResult *)matches[0]).range] integerValue];
myObject.stones = [[string substringWithRange:((NSTextCheckingResult *)matches[1]).range] integerValue];
return myObject;
}
- (NSString *)description
{
return [NSString stringWithFormat:#"%d miles, %d stones", self.miles, self.stones];
}
#end
Then, we will use NSSortDescriptor to sort our array:
MyObject *myObject1 = [MyObject objectWithString:#"4 Miles 400 stones"];
MyObject *myObject2 = [MyObject objectWithString:#"2 Miles 10 stones"];
MyObject *myObject3 = [MyObject objectWithString:#"6 Miles 2 stones"];
NSArray *array = #[myObject1, myObject2, myObject3];
NSSortDescriptor *miles = [[NSSortDescriptor alloc] initWithKey:#"miles" ascending:YES];
NSSortDescriptor *stones = [[NSSortDescriptor alloc] initWithKey:#"stones" ascending:YES];
NSArray *sortDescriptors = #[miles, stones];
NSArray *sortedArray = [array sortedArrayUsingDescriptors:sortDescriptors];
NSLog(#"Sorted: %#", sortedArray);
And the output:
2014-03-05 19:51:54.233 demo[12267:70b] Sorted: (
"2 miles, 10 stones",
"4 miles, 400 stones",
"6 miles, 2 stones" )
It works like a charm my friend!

Answer 2

Your method is correct,
I have tried your way of
NSInteger sort(id a, id b, void* p) {
return [[a valueForKey:(__bridge NSString*)p]
compare:[b valueForKey:(__bridge NSString*)p]
options:NSNumericSearch];
}
it is sorting correctly make sure you call correct dictionary value or correct method, put some break points, you may be sending null values or something.
if you want to reverse the search just use
NSInteger reverseSort(id a, id b, void* p) {
return - [[a valueForKey:(__bridge NSString*)p]
compare:[b valueForKey:(__bridge NSString*)p]
options:NSNumericSearch];
}