How to check iOS version?

There are version like 7.0 or 6.0.3, so we can simply convert version into numerics to compare. if version is like 7.0, simply append another ".0" to it and then take its numeric value.

 int version;
 NSString* iosVersion=[[UIDevice currentDevice] systemVersion];
 NSArray* components=[iosVersion componentsSeparatedByString:@"."];
 if ([components count]==2) {
    iosVersion=[NSString stringWithFormat:@"%@.0",iosVersion];

 }
 iosVersion=[iosVersion stringByReplacingOccurrencesOfString:@"." withString:@""];
 version=[iosVersion integerValue];

For 6.0.0

  if (version==600) {
    // Do something
  }

for 7.0

 if (version==700) {
   // Do something
 }

Basically the same idea as this one https://stackoverflow.com/a/19903595/1937908 but more robust:

#ifndef func_i_system_version_field
#define func_i_system_version_field

inline static int i_system_version_field(unsigned int fieldIndex) {
  NSString* const versionString = UIDevice.currentDevice.systemVersion;
  NSArray<NSString*>* const versionFields = [versionString componentsSeparatedByString:@"."];
  if (fieldIndex < versionFields.count) {
    NSString* const field = versionFields[fieldIndex];
    return field.intValue;
  }
  NSLog(@"[WARNING] i_system_version(%iu): field index not present in version string '%@'.", fieldIndex, versionString);
  return -1; // error indicator
}

#endif

Simply place the above code in a header file.

Usage:

int major = i_system_version_field(0);
int minor = i_system_version_field(1);
int patch = i_system_version_field(2);