Compare version numbers in Objective-C

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
}

Sparkle (the most popular software update framework for MacOS) has a SUStandardVersionComparator class that does this, and also takes into account build numbers and beta markers. I.e. it correctly compares 1.0.5 > 1.0.5b7 or 2.0 (2345) > 2.0 (2100). The code only uses Foundation, so should work fine on iOS as well.

I thought I'd just share a function I pulled together for this. It is not perfect at all. Please take a look that the examples and results. But if you are checking your own version numbers (which I have to do to manage things like database migrations) then this may help a little.

(also, remove the log statements in the method, of course. those are there to help you see what it does is all)

Tests:

[self isVersion:@"1.0" higherThan:@"0.1"];
[self isVersion:@"1.0" higherThan:@"0.9.5"];
[self isVersion:@"1.0" higherThan:@"0.9.5.1"];
[self isVersion:@"1.0.1" higherThan:@"1.0"];
[self isVersion:@"1.0.0" higherThan:@"1.0.1"];
[self isVersion:@"1.0.0" higherThan:@"1.0.0"];

// alpha tests
[self isVersion:@"1.0b" higherThan:@"1.0a"];
[self isVersion:@"1.0a" higherThan:@"1.0b"];
[self isVersion:@"1.0a" higherThan:@"1.0a"];
[self isVersion:@"1.0" higherThan:@"1.0RC1"];
[self isVersion:@"1.0.1" higherThan:@"1.0RC1"];

Results:

1.0 > 0.1
1.0 > 0.9.5
1.0 > 0.9.5.1
1.0.1 > 1.0
1.0.0 < 1.0.1
1.0.0 == 1.0.0
1.0b > 1.0a
1.0a < 1.0b
1.0a == 1.0a
1.0 < 1.0RC1       <-- FAILURE
1.0.1 < 1.0RC1     <-- FAILURE

notice that alpha works but you have to be very careful with it. once you go alpha at some point you cannot extend that by changing any other minor numbers behind it.

Code:

- (BOOL) isVersion:(NSString *)thisVersionString higherThan:(NSString *)thatVersionString {

// LOWER
if ([thisVersionString compare:thatVersionString options:NSNumericSearch] == NSOrderedAscending) {
    NSLog(@"%@ < %@", thisVersionString, thatVersionString);
    return NO;
}

// EQUAL
if ([thisVersionString compare:thatVersionString options:NSNumericSearch] == NSOrderedSame) {
    NSLog(@"%@ == %@", thisVersionString, thatVersionString);
    return NO;
}

NSLog(@"%@ > %@", thisVersionString, thatVersionString);
// HIGHER
return YES;
}

Here is the swift 4.0 + code for version comparison

 let currentVersion = "1.2.0"

 let oldVersion = "1.1.1"

 if currentVersion.compare(oldVersion, options: NSString.CompareOptions.numeric) == ComparisonResult.orderedDescending {
        print("Higher")
    } else {
        print("Lower")
    }

If you know each version number will have exactly 3 integers separated by dots, you can parse them (e.g. using sscanf(3)) and compare them:

const char *version1str = "1.0.1";
const char *version2str = "1.2.5";
int major1, minor1, patch1;
int major2, minor2, patch2;
if(sscanf(version1str, "%d.%d.%d", &major1, &minor1, &patch1) == 3 &&
   sscanf(version2str, "%d.%d.%d", &major2, &minor2, &patch2) == 3)
{
    // Parsing succeeded, now compare the integers
    if(major1 > major2 ||
      (major1 == major2 && (minor1 > minor2 ||
                           (minor1 == minor2 && patch1 > patch2))))
    {
        // version1 > version2
    }
    else if(major1 == major2 && minor1 == minor2 && patch1 == patch2)
    {
        // version1 == version2
    }
    else
    {
        // version1 < version2
    }
}
else
{
    // Handle error, parsing failed
}

Glibc has a function strverscmp and versionsort… unfortunately, not portable to the iPhone, but you can write your own fairly easily. This (untested) re-implementation comes from just reading the documented behavior, and not from reading Glibc's source code.

int strverscmp(const char *s1, const char *s2) {
    const char *b1 = s1, *b2 = s2, *e1, *e2;
    long n1, n2;
    size_t z1, z2;
    while (*b1 && *b1 == *b2) b1++, b2++;
    if (!*b1 && !*b2) return 0;
    e1 = b1, e2 = b2;
    while (b1 > s1 && isdigit(b1[-1])) b1--;
    while (b2 > s2 && isdigit(b2[-1])) b2--;
    n1 = strtol(b1, &e1, 10);
    n2 = strtol(b2, &e2, 10);
    if (b1 == e1 || b2 == e2) return strcmp(s1, s2);
    if (n1 < n2) return -1;
    if (n1 > n2) return 1;
    z1 = strspn(b1, "0"), z2 = strspn(b2, "0");
    if (z1 > z2) return -1;
    if (z1 < z2) return 1;
    return 0;
}

Here is a recursive function that do the works with multiple version formatting of any length. It also works for @"1.0" and @"1.0.0"

static inline NSComparisonResult versioncmp(const NSString * a, const NSString * b)
{
    if ([a isEqualToString:@""] && [b isEqualToString:@""]) {
        return NSOrderedSame;
    }

    if ([a isEqualToString:@""]) {
        a = @"0";
    }

    if ([b isEqualToString:@""]) {
        b = @"0";
    }

    NSArray<NSString*> * aComponents = [a componentsSeparatedByString:@"."];
    NSArray<NSString*> * bComponents = [b componentsSeparatedByString:@"."];
    NSComparisonResult r = [aComponents[0] compare:bComponents[0] options:NSNumericSearch];

    if(r != NSOrderedSame) {
        return r;
    } else {
        NSString* newA = (a.length == aComponents[0].length) ? @"" : [a substringFromIndex:aComponents[0].length+1];
        NSString* newB = (b.length == bComponents[0].length) ? @"" : [b substringFromIndex:bComponents[0].length+1];
        return versioncmp(newA, newB);
    }

}

Test samples :

versioncmp(@"11.5", @"8.2.3");
versioncmp(@"1.5", @"8.2.3");
versioncmp(@"1.0", @"1.0.0");
versioncmp(@"11.5.3.4.1.2", @"11.5.3.4.1.2");

Based on @nathan-de-vries 's answer, I wrote SemanticVersion.swift for comparing Semantic Version, and here is the test cases.