NSScreen+HighestDensity.h

gistfile1.m

#import <Cocoa/Cocoa.h>

@interface NSScreen (HighestDensity)

+ (CGFloat)highestDensity;

@end

NSString+HighestDensity.m

#import "NSScreen+HighestDensity.h"

@implementation NSScreen (HighestDensity)

+ (CGFloat)highestDensity {
  // Support for OSX 10.6
  if (![[NSScreen mainScreen] respondsToSelector:@selector(backingScaleFactor)]) return 1.0f;
  
  NSArray *screens = [NSScreen screens];
  CGFloat highestDensity = 1.0f;
  for (NSScreen *screen in screens) {
    if ([screen backingScaleFactor] > highestDensity) {
      highestDensity = [screen backingScaleFactor];
    }
  }
  return highestDensity;
}

@end

NSStringHighestDensity.m

#import "NSScreen+HighestDensity.h"

@implementation NSScreen (HighestDensity)

+ (CGFloat)highestDensity {
  // Support for OSX 10.6
  if (![[NSScreen mainScreen] respondsToSelector:@selector(backingScaleFactor)]) return 1.0f;
  
  NSArray *screens = [NSScreen screens];
  CGFloat highestDensity = 1.0f;
  for (NSScreen *screen in screens) {
    if ([screen backingScaleFactor] > highestDensity) {
      highestDensity = [screen backingScaleFactor];
    }
  }
  return highestDensity;
}

@end