用于检测所有版本的iPhone和iPad设备。

#define IS_IPAD (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
#define IS_IPHONE (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
#define IS_IPHONE_5 (IS_IPHONE && [[UIScreen mainScreen] bounds].size.height == 568.0)
#define IS_IPHONE_6 (IS_IPHONE && [[UIScreen mainScreen] bounds].size.height == 667.0)
#define IS_IPHONE_6_PLUS (IS_IPHONE && [[UIScreen mainScreen] bounds].size.height == 736.0)
#define IS_RETINA ([[UIScreen mainScreen] scale] == 2.0) 

使用下列守则:

CGFloat screenScale = [[UIScreen mainScreen] scale];

CGRect screenBounds = [[UIScreen mainScreen] bounds]; 

CGSize screenSize = CGSizeMake(screenBounds.size.width * screenScale, screenBounds.size.height * screenScale); 

if (screenSize.height==1136.000000)
{ 
    // Here iPhone 5 View

    // Eg: Nextview~iPhone5.Xib
} else {
   // Previous Phones 

   // Eg : Nextview.xib
}

针对SDK和OS的任何组合进行测试和设计:

斯威夫特

增加了iPad类型。iPad 2和iPad mini是非视网膜iPad。而iPad Mini 2及以上，iPad 3,4, iPad Air, Air 2, Air 3和iPad Pro 9.7具有相同的1024逻辑分辨率。iPad Pro的maxLength为1366。参考

import UIKit

public enum DisplayType {
    case unknown
    case iphone4
    case iphone5
    case iphone6
    case iphone6plus
    case iPadNonRetina
    case iPad
    case iPadProBig
    static let iphone7 = iphone6
    static let iphone7plus = iphone6plus
}

public final class Display {
    class var width:CGFloat { return UIScreen.main.bounds.size.width }
    class var height:CGFloat { return UIScreen.main.bounds.size.height }
    class var maxLength:CGFloat { return max(width, height) }
    class var minLength:CGFloat { return min(width, height) }
    class var zoomed:Bool { return UIScreen.main.nativeScale >= UIScreen.main.scale }
    class var retina:Bool { return UIScreen.main.scale >= 2.0 }
    class var phone:Bool { return UIDevice.current.userInterfaceIdiom == .phone }
    class var pad:Bool { return UIDevice.current.userInterfaceIdiom == .pad }
    class var carplay:Bool { return UIDevice.current.userInterfaceIdiom == .carPlay }
    class var tv:Bool { return UIDevice.current.userInterfaceIdiom == .tv }
    class var typeIsLike:DisplayType {
        if phone && maxLength < 568 {
            return .iphone4
        }
        else if phone && maxLength == 568 {
                return .iphone5
        }
        else if phone && maxLength == 667 {
            return .iphone6
        }
        else if phone && maxLength == 736 {
            return .iphone6plus
        }
        else if pad && !retina {
            return .iPadNonRetina
        }
        else if pad && retina && maxLength == 1024 {
            return .iPad
        }
        else if pad && maxLength == 1366 {
            return .iPadProBig
        }
        return .unknown
    }
}

看看它的实际应用 https://gist.github.com/hfossli/bc93d924649de881ee2882457f14e346

注意:例如，如果iPhone 6处于放大模式，UI就是放大版的iPhone 5。这些功能不是决定设备类型，而是决定显示模式，因此iPhone 5是本例中的理想结果。

objective - c

#define IS_IPAD (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
#define IS_IPHONE (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
#define IS_RETINA ([[UIScreen mainScreen] scale] >= 2.0)

#define SCREEN_WIDTH ([[UIScreen mainScreen] bounds].size.width)
#define SCREEN_HEIGHT ([[UIScreen mainScreen] bounds].size.height)
#define SCREEN_MAX_LENGTH (MAX(SCREEN_WIDTH, SCREEN_HEIGHT))
#define SCREEN_MIN_LENGTH (MIN(SCREEN_WIDTH, SCREEN_HEIGHT))
#define IS_ZOOMED (IS_IPHONE && SCREEN_MAX_LENGTH == 736.0)

#define IS_IPHONE_4_OR_LESS (IS_IPHONE && SCREEN_MAX_LENGTH < 568.0)
#define IS_IPHONE_5 (IS_IPHONE && SCREEN_MAX_LENGTH == 568.0)
#define IS_IPHONE_6 (IS_IPHONE && SCREEN_MAX_LENGTH == 667.0)
#define IS_IPHONE_6P (IS_IPHONE && SCREEN_MAX_LENGTH == 736.0)

用法:http://pastie.org/9687735

注意:例如，如果iPhone 6处于放大模式，UI就是放大版的iPhone 5。这些功能不是决定设备类型，而是决定显示模式，因此iPhone 5是本例中的理想结果。

if ((int)[[UIScreen mainScreen] bounds].size.height == 568)
{
    // This is iPhone 5 screen
} else {
    // This is iPhone 4 screen
}

借用Samrat Mazumdar的回答，这里有一个估算设备屏幕大小的简单方法。它适用于最新的设备，但在未来的设备上可能会失败(正如所有猜测的方法一样)。如果设备正在镜像，它也会混淆(返回设备的屏幕大小，而不是镜像的屏幕大小)

#define SCREEN_SIZE_IPHONE_CLASSIC 3.5
#define SCREEN_SIZE_IPHONE_TALL 4.0
#define SCREEN_SIZE_IPAD_CLASSIC 9.7

+ (CGFloat)screenPhysicalSize
{
    if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
    {
        CGSize result = [[UIScreen mainScreen] bounds].size;
        if (result.height < 500)
            return SCREEN_SIZE_IPHONE_CLASSIC;  // iPhone 4S / 4th Gen iPod Touch or earlier
        else
            return SCREEN_SIZE_IPHONE_TALL;  // iPhone 5
    }
    else
    {
        return SCREEN_SIZE_IPAD_CLASSIC; // iPad
    }
} 

如果项目是用Xcode 6创建的，那么使用下面提到的代码来检测设备。

printf("\nDetected Resolution : %d x %d\n\n",(int)[[UIScreen mainScreen] nativeBounds].size.width,(int)[[UIScreen mainScreen] nativeBounds].size.height);

if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone){
    if ([[UIScreen mainScreen] respondsToSelector: @selector(scale)])
    {
        if([[UIScreen mainScreen] nativeBounds].size.height == 960 || [[UIScreen mainScreen] nativeBounds].size.height == 480){
            printf("Device Type : iPhone 4,4s ");

        }else if([[UIScreen mainScreen] nativeBounds].size.height == 1136){
            printf("Device Type : iPhone 5,5S/iPod 5 ");

        }else if([[UIScreen mainScreen] nativeBounds].size.height == 1334){
            printf("Device Type : iPhone 6 ");

        }else if([[UIScreen mainScreen] nativeBounds].size.height == 2208){
            printf("Device Type : iPhone 6+ ");

        }
    }
}else{
    printf("Device Type : iPad");
}

如果项目是在Xcode 5中创建并在Xcode 6中打开的，那么使用下面提到的代码来检测设备。(如果没有为iPhone 6,6+分配启动图像，此代码有效)

printf("\nDetected Resolution : %d x %d\n\n",(int)[[UIScreen mainScreen] nativeBounds].size.width,(int)[[UIScreen mainScreen] nativeBounds].size.height);
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone){
    if ([[UIScreen mainScreen] respondsToSelector: @selector(scale)])
    {
       if([[UIScreen mainScreen] nativeBounds].size.height == 960 || [[UIScreen mainScreen] nativeBounds].size.height == 480){
            printf("Device Type : iPhone 4,4s");
            appType=1;
        }else if([[UIScreen mainScreen] nativeBounds].size.height == 1136 || [[UIScreen mainScreen] nativeBounds].size.height == 1704){
            printf("Device Type : iPhone 5,5S,6,6S/iPod 5 ");
            appType=3;
        }
    }
}else{
    printf("Device Type : iPad");
    appType=2;
}

如果你仍然在使用Xcode 5，那么使用下面的代码来检测设备(iPhone 6和6+将不会被检测到)

printf("\nDetected Resolution : %d x %d\n\n",(int)[[UIScreen mainScreen] bounds].size.width,(int)[[UIScreen mainScreen] bounds].size.height);
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone){
    if ([[UIScreen mainScreen] respondsToSelector: @selector(scale)])
    {
        CGSize result = [[UIScreen mainScreen] bounds].size;
        CGFloat scale = [UIScreen mainScreen].scale;
        result = CGSizeMake(result.width * scale, result.height * scale);
        if(result.height == 960 || result.height == 480){
            printf("Device Type : iPhone 4,4S ");

        }else if(result.height == 1136){
            printf("Device Type : iPhone 5s/iPod 5");

        }
    }
}else{
    printf("Device Type : iPad");

}