斯威夫特5

func run() {
    let version = OperatingSystemVersion(majorVersion: 13, minorVersion: 0, patchVersion: 0)
    if ProcessInfo.processInfo.isOperatingSystemAtLeast(version) {
        runNewCode()
    } else {
        runLegacyCode()
    }
}

func runNewCode() {
    guard #available(iOS 13.0, *) else {
        fatalError()
    }
    // do new stuff
}

func runLegacyCode() {
    // do old stuff
}

如果你想查看WatchOS。

斯威夫特

let watchOSVersion = WKInterfaceDevice.currentDevice().systemVersion
print("WatchOS version: \(watchOSVersion)")

objective - c

NSString *watchOSVersion = [[WKInterfaceDevice currentDevice] systemVersion];
NSLog(@"WatchOS version: %@", watchOSVersion);

如果你正在使用Swift 2，并且你想要检查操作系统版本以使用某个API，你可以使用新的可用性特性:

if #available(iOS 8, *) {
    //iOS 8+ code here.
}
else {
    //Code for iOS 7 and older versions.
    //An important note: if you use #availability, Xcode will also 
    //check that you don't use anything that was introduced in iOS 8+
    //inside this `else` block. So, if you try to use UIAlertController
    //here, for instance, it won't compile. And it's great.
}

我写这个答案是因为它是谷歌中swift 2 check系统版本查询的第一个问题。

let Device = UIDevice.currentDevice()
let iosVersion = NSString(string: Device.systemVersion).doubleValue

let iOS8 = iosVersion >= 8
let iOS7 = iosVersion >= 7 && iosVersion < 8

检查为

if(iOS8)
{

}
else 
{
}  

斯威夫特5

我们不需要创建扩展，因为ProcessInfo给了我们版本信息。你可以在下面看到iOS的示例代码。

let os = ProcessInfo().operatingSystemVersion

switch (os.majorVersion, os.minorVersion, os.patchVersion) {
case (let x, _, _) where x < 8:
    print("iOS < 8.0.0")

case (8, 0, _):
    print("iOS >= 8.0.0, < 8.1.0")

case (8, _, _):
    print("iOS >= 8.1.0, < 9.0")

case (9, _, _):
    print("iOS >= 9.0.0")

default:
    print("iOS >= 10.0.0")
}

参考:http://nshipster.com/swift-system-version-checking/

let osVersion = NSProcessInfo.processInfo().operatingSystemVersion
let versionString = osVersion.majorVersion.description + "." + osVersion.minorVersion.description + "." + osVersion.patchVersion.description
print(versionString)