Compare string versions

gistfile1.m

+ (BOOL)currentVersionIsGreaterOrEqualThan:(NSString *)baseVersion
{
    // baseVersion is something like @"1.0.5"
    NSArray *baseVersionComponents = [baseVersion componentsSeparatedByString:@"."];
    
    NSString *version = [UIDevice currentDevice].systemVersion;
    NSArray *components = [version componentsSeparatedByString:@"."];
    
    // the number of components of both version must be the same
    for (int i = 0; i < [components count]; i++) {
        if ([components[i] integerValue] < [baseVersionComponents[i] integerValue]) {
            return NO;
        }
    }
    
    return YES;
}