检测设备是否为iPhone X的最佳和最简单的方法是，

https://github.com/stephanheilner/UIDevice-DisplayName

var systemInfo = utsname()
uname(&systemInfo)
let machineMirror = Mirror(reflecting: systemInfo.machine)
let identifier = machineMirror.children.reduce("") { identifier, element in
guard let value = element.value as? Int8 , value != 0 else { return identifier}
            return identifier + String(UnicodeScalar(UInt8(value)))}

标识符是iPhone10,3或者iPhone10,6对于iPhone X。

检查设备型号/机器名称，不要在你的代码中直接使用点/像素计数，这是硬代码，对设备硬件没有意义，设备型号是设备类型匹配的唯一标识符。

#import <sys/utsname.h>

NSString* deviceName()
{
    struct utsname systemInfo;
    uname(&systemInfo);

    return [NSString stringWithCString:systemInfo.machine
                          encoding:NSUTF8StringEncoding];
}

结果:

@"iPhone10,3" on iPhone X (CDMA)
@"iPhone10,6" on iPhone X (GSM)

参考这个答案。

完整的代码实现:

#import <sys/utsname.h>

NSString * GetDeviceModel(void)
{
    static dispatch_once_t onceToken;
    static NSString *strModelID = nil;

    dispatch_once(&onceToken, ^{
#if TARGET_IPHONE_SIMULATOR
        strModelID = NSProcessInfo.processInfo.environment[@"SIMULATOR_MODEL_IDENTIFIER"];
#else
        struct utsname systemInfo;

        uname(&systemInfo);
        strModelID = [NSString stringWithCString:systemInfo.machine encoding:NSUTF8StringEncoding];
#endif
    });

    return strModelID;
}

// See the `Hardware strings` in https://en.wikipedia.org/wiki/List_of_iOS_devices
BOOL IsiPhoneX(void)
{
    NSString *strModelID = GetDeviceModel();

    return [strModelID isEqualToString:@"iPhone10,3"] || [strModelID isEqualToString:@"iPhone10,6"];
}

BOOL IsNotchiPhone(void)
{
    NSArray<NSString *> *notchiModels = @[
        @"iPhone10,3", @"iPhone10,6", // iPhone X
        @"iPhone11,2", @"iPhone11,4", @"iPhone11,6", // iPhone XS (Max)
        @"iPhone11,8", // iPhone XR
        @"iPhone12,1", @"iPhone12,3", @"iPhone12,5", // iPhone 11 (Pro (Max))
        @"iPhone13,1", @"iPhone13,2", @"iPhone13,3", @"iPhone13,4", // iPhone 12 ([mini]|[Pro (Max)])
    ];

    return [notchiModels containsObject:GetDeviceModel()];
}

SWIFT 4+回答

iPhone X, XR, XS, XSMAX, 11 Pro, 11 Pro Max:

注:需实物设备进行测试

参考

 let deviceType = UIDevice.current.modelName
        switch deviceType {
        case "iPhone10,3", "iPhone10,6":
            print("iPhoneX")
        case "iPhone11,2":
            print("iPhone XS")
        case "iPhone11,4":
            print("iPhone XS Max")
        case "iPhone11,6":
            print("iPhone XS Max China")
        case "iPhone11,8":
            print("iPhone XR")
        case "iPhone12,3":
            print("iPhone 11 Pro")
        case "iPhone12,5":
            print("iPhone 11 Pro Max")
        default:
            break
}

extension UIDevice {
    var modelName: String {
        var systemInfo = utsname()
        uname(&systemInfo)
        let machineMirror = Mirror(reflecting: systemInfo.machine)
        let identifier = machineMirror.children.reduce("") { identifier, element in
            guard let value = element.value as? Int8, value != 0 else { return identifier }
            return identifier + String(UnicodeScalar(UInt8(value)))
        }
        return identifier
    }
}

使用简单的方法检测任何设备。像下面,

func isPhoneDevice() -> Bool {
    return UIDevice.current.userInterfaceIdiom == .phone
}

func isDeviceIPad() -> Bool {
    return UIDevice.current.userInterfaceIdiom == .pad
}

func isPadProDevice() -> Bool {
    let SCREEN_WIDTH: CGFloat = UIScreen.main.bounds.size.width
    let SCREEN_HEIGHT: CGFloat = UIScreen.main.bounds.size.height
    let SCREEN_MAX_LENGTH: CGFloat = fmax(SCREEN_WIDTH, SCREEN_HEIGHT)

    return UIDevice.current.userInterfaceIdiom == .pad && SCREEN_MAX_LENGTH == 1366.0
}

func isPhoneXandXSDevice() -> Bool {
    let SCREEN_WIDTH = CGFloat(UIScreen.main.bounds.size.width)
    let SCREEN_HEIGHT = CGFloat(UIScreen.main.bounds.size.height)
    let SCREEN_MAX_LENGTH: CGFloat = fmax(SCREEN_WIDTH, SCREEN_HEIGHT)

    return UIDevice.current.userInterfaceIdiom == .phone && SCREEN_MAX_LENGTH == 812.0
}

func isPhoneXSMaxandXRDevice() -> Bool {
    let SCREEN_WIDTH = CGFloat(UIScreen.main.bounds.size.width)
    let SCREEN_HEIGHT = CGFloat(UIScreen.main.bounds.size.height)
    let SCREEN_MAX_LENGTH: CGFloat = fmax(SCREEN_WIDTH, SCREEN_HEIGHT)

    return UIDevice.current.userInterfaceIdiom == .phone && SCREEN_MAX_LENGTH == 896.0
}

像这样叫，

if isPhoneDevice() {
     // Your code
}

对于那些获得2001px而不是2436px的原生边界高度的人(比如我)，这是因为你使用的是iOS 11 (Xcode 8而不是Xcode 9)之前的旧SDK构建的应用程序。使用旧SDK, iOS将在iPhone X上显示应用程序的“黑盒子”，而不是将屏幕边缘扩展到顶部的“传感器缺口”。这减少了屏幕大小，这就是为什么该属性返回2001而不是2436。

如果您只对设备检测感兴趣，最简单的解决方案是检查两个大小。我使用这种方法来检测FaceID，同时使用一个旧的Xcode SDK，它没有ENUM值指定生物特征类型。在这种情况下，使用屏幕高度进行设备检测似乎是知道设备是否具有FaceID还是TouchID的最佳方法，而无需更新Xcode。

在看完所有的答案后，我最后是这么做的:

解决方案(兼容Swift 4.1)

extension UIDevice {
    static var isIphoneX: Bool {
        var modelIdentifier = ""
        if isSimulator {
            modelIdentifier = ProcessInfo.processInfo.environment["SIMULATOR_MODEL_IDENTIFIER"] ?? ""
        } else {
            var size = 0
            sysctlbyname("hw.machine", nil, &size, nil, 0)
            var machine = [CChar](repeating: 0, count: size)
            sysctlbyname("hw.machine", &machine, &size, nil, 0)
            modelIdentifier = String(cString: machine)
        }

        return modelIdentifier == "iPhone10,3" || modelIdentifier == "iPhone10,6"
    }

    static var isSimulator: Bool {
        return TARGET_OS_SIMULATOR != 0
    }
}

Use

if UIDevice.isIphoneX {
    // is iPhoneX
} else {
    // is not iPhoneX
}

Note

Pre Swift 4.1你可以检查应用程序是否在模拟器上运行，就像这样:

TARGET_OS_SIMULATOR != 0

从Swift 4.1开始，你可以使用目标环境平台条件检查应用程序是否在模拟器上运行:

#if targetEnvironment(simulator)
    return true
#else
    return false
#endif

(旧的方法仍然有效，但这个新方法更经得起未来的考验)