Compare version numbers in Objective-C

Question

I am writing an application that receives data with items and version numbers. The numbers are formatted like "1.0.1" or "1.2.5". How can I compare these version numbers? I think they have to be formatted as a string first, no? What options do I have to determine that "1.2.5" comes after "1.0.1"?

Answer 1

This is the simplest way to compare versions, keeping in mind that "1" < "1.0" < "1.0.0":

NSString* requiredVersion = @"1.2.0"; NSString* actualVersion = @"1.1.5";  if ([requiredVersion compare:actualVersion options:NSNumericSearch] == NSOrderedDescending) {   // actualVersion is lower than the requiredVersion } 

Answer 2

I'll add my method, which compares strictly numeric versions (no a, b, RC etc.) with any number of components.

+ (NSComparisonResult)compareVersion:(NSString*)versionOne toVersion:(NSString*)versionTwo {     NSArray* versionOneComp = [versionOne componentsSeparatedByString:@"."];     NSArray* versionTwoComp = [versionTwo componentsSeparatedByString:@"."];      NSInteger pos = 0;      while ([versionOneComp count] > pos || [versionTwoComp count] > pos) {         NSInteger v1 = [versionOneComp count] > pos ? [[versionOneComp objectAtIndex:pos] integerValue] : 0;         NSInteger v2 = [versionTwoComp count] > pos ? [[versionTwoComp objectAtIndex:pos] integerValue] : 0;         if (v1 < v2) {             return NSOrderedAscending;         }         else if (v1 > v2) {             return NSOrderedDescending;         }         pos++;     }      return NSOrderedSame; }