斯威夫特的另一种方式:

//MARK: -  Device Check
let iPad = UIUserInterfaceIdiom.Pad
let iPhone = UIUserInterfaceIdiom.Phone
@available(iOS 9.0, *) /* AppleTV check is iOS9+ */
let TV = UIUserInterfaceIdiom.TV

extension UIDevice {
    static var type: UIUserInterfaceIdiom 
        { return UIDevice.currentDevice().userInterfaceIdiom }
}

用法:

if UIDevice.type == iPhone {
    //it's an iPhone!
}

if UIDevice.type == iPad {
    //it's an iPad!
}

if UIDevice.type == TV {
    //it's an TV!
}

注意:如果你的应用只针对iPhone设备，在iPhone兼容模式下运行的iPad将为以下语句返回false:

#define IPAD     UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad

检测实体iPad设备的正确方法是:

#define IS_IPAD_DEVICE      ([(NSString *)[UIDevice currentDevice].model hasPrefix:@"iPad"])

斯威夫特的另一种方式:

//MARK: -  Device Check
let iPad = UIUserInterfaceIdiom.Pad
let iPhone = UIUserInterfaceIdiom.Phone
@available(iOS 9.0, *) /* AppleTV check is iOS9+ */
let TV = UIUserInterfaceIdiom.TV

extension UIDevice {
    static var type: UIUserInterfaceIdiom 
        { return UIDevice.currentDevice().userInterfaceIdiom }
}

用法:

if UIDevice.type == iPhone {
    //it's an iPhone!
}

if UIDevice.type == iPad {
    //it's an iPad!
}

if UIDevice.type == TV {
    //it's an TV!
}

对于最新版本的iOS，只需添加UITraitCollection:

extension UITraitCollection {

    var isIpad: Bool {
        return horizontalSizeClass == .regular && verticalSizeClass == .regular
    }
}

然后在UIViewController中检查:

if traitCollection.isIpad { ... }

UI_USER_INTERFACE_IDIOM()只返回iPad如果应用程序是iPad或通用。如果这是一款运行在iPad上的iPhone应用，那么它就不会这么做。所以你应该检查模型。

在Swift 4.2和Xcode 10中

if UIDevice().userInterfaceIdiom == .phone {
    //This is iPhone
} else if UIDevice().userInterfaceIdiom == .pad { 
    //This is iPad
} else if UIDevice().userInterfaceIdiom == .tv {
    //This is Apple TV
}

如果你想检测特定的设备

let screenHeight = UIScreen.main.bounds.size.height
if UIDevice().userInterfaceIdiom == .phone {
    if (screenHeight >= 667) {
        print("iPhone 6 and later")
    } else if (screenHeight == 568) {
        print("SE, 5C, 5S")
    } else if(screenHeight<=480){
        print("4S")
    }
} else if UIDevice().userInterfaceIdiom == .pad { 
    //This is iPad
}