这是对Matt MC的回答的重复。只是UIScreen上的一个类别。

#import "UIScreen+Util.h"

@implementation UIScreen (Util)

+ (BOOL) isRetinaDisplay {
    static BOOL retina = NO;
    static BOOL alreadyChecked = NO;
    if (!alreadyChecked) {
        UIScreen *mainScreen = self.mainScreen;
        if (mainScreen) {
            retina = mainScreen.scale > 1.0;
            alreadyChecked = YES;
        }
    }
    return retina;
}

@end

@sickp的答案是正确的。为了简化操作，将这一行添加到共享中。pch文件:

#define IS_RETINA ([[UIScreen mainScreen] respondsToSelector:@selector(displayLinkWithTarget:selector:)] && ([UIScreen mainScreen].scale >= 2.0))

然后在任何文件中你都可以这样做:

if(IS_RETINA)
{
   // etc..
}

SSToolkit有一个这样做的方法:

http://sstoolk.it/documentation/Categories/UIScreen (SSToolkitAdditions) . html

它的用法如下:

[[UIScreen mainScreen] isRetinaDisplay];

比较浮点值是否相等总是让人感觉有点不可靠。 两者我都喜欢

[UIScreen mainScreen].scale > 1.0;

or

[UIScreen mainScreen].scale < 2.0;

+(BOOL)iPhoneRetina{
    return ([[UIScreen mainScreen] respondsToSelector:@selector(displayLinkWithTarget:selector:)] && ([UIScreen mainScreen].scale == 2.0))?1:0;
}

primulaveris's的修改版本，以简化最常见的用例。我用的是swift 2.2，但这应该没有关系。

extension UIScreen {
    static var isRetina: Bool {
        return screenScale >= 2.0
    }

    static var isRetinaHD: Bool {
        return screenScale >= 3.0
    }

    static var screenScale:CGFloat {
        return UIScreen.mainScreen().scale
    }
}

然后像这样简单地使用它们

print(UIScreen.isRetina)
print(UIScreen.isRetinaHD)
print(UIScreen.screenScale)