Objective-C Version comparison [duplicate] - objective-c

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Possible Duplicate:
Comparing version numbers
How to use compare on a version number where theres less parts in one number in Objective-C?
I am attempting to sort an NSMutableArray of custom objects based on a property called referenceID which essentially resembles a version number.
It seems that treating referenceID as an NSNumber and sorting it using compareTo: almost gets it right, but where it breaks is cases such as:
Result: Should Be:
1.1.1 1.1.1
1.1.10 1.1.2
1.1.2 ...
... 1.1.9
1.1.9 1.1.10
(Where ... is 1.1.2 through 1.1.9)
Are there any built in functions that will sort this properly? Or should I get started writing the sorting algorithm?

Answer 1

If your reference id is a string, you can use localizedStandardCompare:, which compares numbers in strings according to their numerical value.
Example (with sortedArrayUsingComparator, because that is used by the OP in his comment):
NSArray *versions = #[#"2.1.1.1", #"2.10.1", #"2.2.1"];
NSArray *sorted = [versions sortedArrayUsingComparator:^NSComparisonResult(NSString *s1, NSString *s2) {
return [s1 localizedStandardCompare:s2];
}];
NSLog(#"%#", sorted);
Output:
2012-11-29 23:51:28.962 test27[1962:303] (
"2.1.1.1",
"2.2.1",
"2.10.1"
)

Answer 2

sort it with a block
#autoreleasepool {
//in this example, array of NSStrings
id array = #[#"1.1.1",#"2.2",#"1.0",#"1.1.0.1",#"1.1.2.0", #"1.0.3", #"2.1.1.1", #"2.1.1", #"2.1.10"];
//block
id sorted = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
NSArray *comps1 = [obj1 componentsSeparatedByString:#"."];
NSArray *comps2 = [obj2 componentsSeparatedByString:#"."];
//get ints from comps
int res1 = 0;
for (int i=0; i<comps1.count; i++) {
res1 += [comps1[i] intValue] * (4 - i);
}
int res2 = 0;
for (int i=0; i<comps2.count; i++) {
res2 += [comps2[i] intValue] * (4 - i);
}
return res1<res2 ? NSOrderedAscending : res1>res2 ? NSOrderedSame : NSOrderedDescending;
}];
NSLog(#"%#", sorted);
}