Check iOS version and write conditional code

I strongly recommend not to use iOS version numbers to write conditional code. There is usually a more reliable method of checking whether a particular feature available or not. But if you are in a deadly situation and hardly needed the version number then you can get iOS version number by UIDevice class. Here is the real code –

NSString *currSysVer = [[UIDevice currentDevice] systemVersion];

Here is how you can use this to write conditional code –

// A system version of 3.1 or greater is required to use CADisplayLink. The NSTimer
// class is used as fallback when it isn't available.
NSString *reqSysVer = @"3.1";
NSString *currSysVer = [[UIDevice currentDevice] systemVersion];
if ([currSysVer compare:reqSysVer options:NSNumericSearch] != NSOrderedAscending)
    displayLinkSupported = TRUE;

Above code works great but writing this condition is real pain every time. The solution of this is Macros. We can use Macros in objective c and reduce the line of code in above code.

Here is real code using Macros –

/*
 *  System Versioning Preprocessor Macros
 */
 
#define SYSTEM_VERSION_EQUAL_TO(v)                  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedSame)
#define SYSTEM_VERSION_GREATER_THAN(v)              ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedDescending)
#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v)  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedAscending)
#define SYSTEM_VERSION_LESS_THAN(v)                 ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)
#define SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(v)     ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedDescending)

And how we can use these Macros to write conditional code –

/*
 *  Usage
 */
 
if (SYSTEM_VERSION_LESS_THAN(@"4.0")) {
    ...
}
 
if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"3.1.1")) {
    ...
}

Hope these Macros will save someone's time.I guess you came to this post by searching similar kind of issues in any of the search engine and hope that this resolved your problem. If you find this tips useful, just drop a line below and share the link to others and who knows they might find it useful too. 

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