在Swift 3中，你可以使用我的简单类KRDeviceType。

https://github.com/ulian-onua/KRDeviceType

它有很好的文档，并支持运算符==，>=，<=。

例如，要检测设备是否有iPhone 6/6s/7的边界，你可以使用next比较:

if KRDeviceType() == .iPhone6 {
// Perform appropiate operations
}

要检测设备是否有iPhone 5/5S/SE或更早(iPhone 4s)的边界，您可以使用下一个比较:

if KRDeviceType() <= .iPhone5 {   //iPhone 5/5s/SE of iPhone 4s
// Perform appropiate operations (for example, set up constraints for those old devices)
}

Add a 'New Swift File'-> AppDelegateEx.swift add an extension to AppDelegate import UIKit extension AppDelegate { class func isIPhone5 () -> Bool{ return max(UIScreen.mainScreen().bounds.width, UIScreen.mainScreen().bounds.height) == 568.0 } class func isIPhone6 () -> Bool { return max(UIScreen.mainScreen().bounds.width, UIScreen.mainScreen().bounds.height) == 667.0 } class func isIPhone6Plus () -> Bool { return max(UIScreen.mainScreen().bounds.width, UIScreen.mainScreen().bounds.height) == 736.0 } } usage: if AppDelegate.isIPhone5() { collectionViewTopConstraint.constant = 2 }else if AppDelegate.isIPhone6() { collectionViewTopConstraint.constant = 20 }

我用hfossli的答案翻译给了Swift

let IS_IPAD = UIDevice.currentDevice().userInterfaceIdiom == .Pad
let IS_IPHONE = UIDevice.currentDevice().userInterfaceIdiom == .Phone
let IS_RETINA = UIScreen.mainScreen().scale >= 2.0

let SCREEN_WIDTH = UIScreen.mainScreen().bounds.size.width
let SCREEN_HEIGHT = UIScreen.mainScreen().bounds.size.height
let SCREEN_MAX_LENGTH = max(SCREEN_WIDTH, SCREEN_HEIGHT)
let SCREEN_MIN_LENGTH = min(SCREEN_WIDTH, SCREEN_HEIGHT)

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

这个问题已经得到了上百次的回答，但这个解决方案对我来说是最好的，并且在引入新设备时帮助解决了这个问题，而我没有定义一个大小。

Swift 5助手:

extension UIScreen {
    func phoneSizeInInches() -> CGFloat {
        switch (self.nativeBounds.size.height) {
        case 960, 480:
            return 3.5  //iPhone 4
        case 1136:
            return 4    //iPhone 5
        case 1334:
            return 4.7  //iPhone 6
        case 2208:
            return 5.5  //iPhone 6 Plus
        case 2436:
            return 5.8  //iPhone X
        case 1792:
            return 6.1  //iPhone XR
        case 2688:
            return 6.5  //iPhone XS Max
        default:
            let scale = self.scale
            let ppi = scale * 163
            let width = self.bounds.size.width * scale
            let height = self.bounds.size.height * scale
            let horizontal = width / ppi, vertical = height / ppi
            let diagonal = sqrt(pow(horizontal, 2) + pow(vertical, 2))
            return diagonal
        }
    }
}

这是因为记住手机的英寸大小很容易，比如“5.5英寸”或“4.7英寸”，但很难记住准确的像素大小。

if UIScreen.main.phoneSizeInInches() == 4 {
  //do something with only 4 inch iPhones
}

这也给了你这样做的机会:

if UIScreen.main.phoneSizeInInches() < 5.5 {
  //do something on all iPhones smaller than the plus
}

默认值:尝试使用屏幕大小和比例来尝试计算对角线英寸。这是为了防止出现一些新的设备大小，它将尽力确定和代码，如最后一个例子，应该仍然工作。

这里是正确的测试设备，不依赖于方向

- (BOOL)isIPhone5
{
    CGSize size = [[UIScreen mainScreen] bounds].size;
    if (MIN(size.width,size.height) == 320 && MAX(size.width,size.height == 568)) {
        return YES;
    }
    return NO;
}

在Swift, iOS 8+项目中，我喜欢在UIScreen上做一个扩展，比如:

extension UIScreen {

    var isPhone4: Bool {
        return self.nativeBounds.size.height == 960;
    }

    var isPhone5: Bool {
        return self.nativeBounds.size.height == 1136;
    }

    var isPhone6: Bool {
        return self.nativeBounds.size.height == 1334;
    }

    var isPhone6Plus: Bool {
        return self.nativeBounds.size.height == 2208;
    }

}

(注意:nativeBounds是以像素为单位)。

然后代码会是这样的:

if UIScreen.mainScreen().isPhone4 {
    // do smth on the smallest screen
}

因此，代码清楚地表明这是对主屏幕的检查，而不是对设备模型的检查。