[iphone] How can we programmatically detect which iOS version is device running on?



Answers

Update

From iOS 8 we can use the new isOperatingSystemAtLeastVersion method on NSProcessInfo

   NSOperatingSystemVersion ios8_0_1 = (NSOperatingSystemVersion){8, 0, 1};
   if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion:ios8_0_1]) {
      // iOS 8.0.1 and above logic
   } else {
      // iOS 8.0.0 and below logic
   }

Beware that this will crash on iOS 7, as the API didn't exist prior to iOS 8. If you're supporting iOS 7 and below, you can safely perform the check with

if ([NSProcessInfo instancesRespondToSelector:@selector(isOperatingSystemAtLeastVersion:)]) {
  // conditionally check for any version >= iOS 8 using 'isOperatingSystemAtLeastVersion'
} else {
  // we're on iOS 7 or below
}

Original answer iOS < 8

For the sake of completeness, here's an alternative approach proposed by Apple itself in the iOS 7 UI Transition Guide, which involves checking the Foundation Framework version.

if (floor(NSFoundationVersionNumber) <= NSFoundationVersionNumber_iOS_6_1) {
   // Load resources for iOS 6.1 or earlier
} else {
   // Load resources for iOS 7 or later
}
Question

This question already has an answer here:

I want to check if the user is running the app on iOS less than 5.0 and display a label in the app.

How do I detect which iOS is running on user's device programmatically?

Thanks!




To get more specific version number information with major and minor versions separated:

NSString* versionString = [UIDevice currentDevice].systemVersion;
NSArray* vN = [versionString componentsSeparatedByString:@"."];

The array vN will contain the major and minor versions as strings, but if you want to do comparisons, version numbers should be stored as numbers (ints). You can add this code to store them in the C-array* versionNumbers:

int versionNumbers[vN.count];
for (int i = 0; i < sizeof(versionNumbers)/sizeof(versionNumbers[0]); i++)
    versionNumbers[i] = [[vN objectAtIndex:i] integerValue];

* C-arrays used here for more concise syntax.




A simple check for iOS version less than 5 (all versions):

if([[[UIDevice currentDevice] systemVersion] integerValue] < 5){
        // do something
};



[[UIDevice currentDevice] systemVersion]



[[[UIDevice currentDevice] systemVersion] floatValue]



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