Simple Objective-C Class to Compare Version Number (X.X.X)
I needed to compare version strings to determine whether data needs to be manually migrated. Most references I found suggested to use - [NSString compare:options:NSNumericSearch]. This is not accurate when comparing between strings like "2.4.06" and "2.4.4", which will return "2.4.06" as the more recent version, when "2.4.4" should be instead.
I found a better comparator at https://github.com/nicolasembleton/NEVersionCompare, but to me, it seemed to be a little heavy, with a wrapper class around each version string, and several object creations (- [NSString subStringWithRange:], - [NSString stringByAppendingString:], etc). It also assumed that versions are made of four groups, and memory is assigned to hold their values.
As an exercise to myself, I created this class with the goal of improving ease of use (No wrapper class, just one class method), increasing performance and reducing memory footprint by parsing strings directly. I have not done a performance comparison as this is not a project to discredit other people's work, and I feel the differences will be negligible. Theoretically this should perform slightly faster.
Non-numerical characters are ignored. First character of a string must begin with a number, or 0 will be assumed. Here are some comparison results:
1.3.0 is equal to 1.3.0
1.3.0 is smaller than 1.3.1
1.3.0 is greater than 1.2.9
1.3.0 is smaller than 1.3.0.1 (1.3.0 is treated as 1.3.0.0)
1.3.0.0 is equal to 1.3.0
1.3.0A is equal to 1.3.0B (non-numeric is ignored)
1.3.100 is greater than 1.3.1
..3.100 is smaller than 1..3. (first group of ..3.100 is assumed to be 0)
.a.3.100 is greater than b.1.3. (0.3.100.0 is greater than 0.1.3.0)
I've also included the EQVersionCompareTests test class which produced this output.
If your version string contains non-numeric characters, then this class may not be suitable for you. Version strings for iOS should also only include numbers (ref: https://developer.apple.com/library/ios/documentation/IDEs/Conceptual/AppDistributionGuide/ConfiguringYourApp/ConfiguringYourApp.html).
Import EQVersionCompare.h & EQVersionCompare.m into your project.
Compare two version strings with + [EQVersionCompare compareVersion:with:]. First version string is greater than second one if it returns NSOrderedAscending or EQVersionCompareSmaller.
MIT License. Use in your projects and change it as desired.