获取系统的当前版本并拆分它。 所以你可以得到大调和小调版本。

let sys_version = UIDevice.current.systemVersion
let all_version = sys_version.components(separatedBy: ".")
print("Major version : \(all_version[0])")
print("Minor version : \(all_version[1])")

细节

Xcode 10.2.1 (10E1001)

链接

OperatingSystemVersion

解决方案

extension OperatingSystemVersion {
    func getFullVersion(separator: String = ".") -> String {
        return "\(majorVersion)\(separator)\(minorVersion)\(separator)\(patchVersion)"
    }
}

let os = ProcessInfo().operatingSystemVersion
print(os.majorVersion)          // 12
print(os.minorVersion)          // 2
print(os.patchVersion)          // 0
print(os.getFullVersion())      // 12.2.0

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

快4.倍

func iOS_VERSION_EQUAL_TO(version: String) -> Bool {
    return UIDevice.current.systemVersion.compare(version, options: NSString.CompareOptions.numeric) == ComparisonResult.orderedSame
}

func iOS_VERSION_GREATER_THAN(version: String) -> Bool {
    return UIDevice.current.systemVersion.compare(version, options: NSString.CompareOptions.numeric) == ComparisonResult.orderedDescending
}

func iOS_VERSION_GREATER_THAN_OR_EQUAL_TO(version: String) -> Bool {
    return UIDevice.current.systemVersion.compare(version, options: NSString.CompareOptions.numeric) != ComparisonResult.orderedAscending
}

func iOS_VERSION_LESS_THAN(version: String) -> Bool {
    return UIDevice.current.systemVersion.compare(version, options: NSString.CompareOptions.numeric) == ComparisonResult.orderedAscending
}

func iOS_VERSION_LESS_THAN_OR_EQUAL_TO(version: String) -> Bool {
    return UIDevice.current.systemVersion.compare(version, options: NSString.CompareOptions.numeric) != ComparisonResult.orderedDescending
}

用法:

if iOS_VERSION_GREATER_THAN_OR_EQUAL_TO(version: "11.0") {
    //Do something!
}

附:KVISH回答翻译成Swift 4。x和重命名函数，因为我专门为iOS应用程序使用这个片段。

在Swift 2及更高版本中，检查系统版本(以及许多其他版本)最简单和最简单的方法是:

if #available(iOS 9.0, *) { // check for iOS 9.0 and later

}

此外，使用#available你可以检查这些版本:

iOS
iOSApplicationExtension
macOS
macOSApplicationExtension
watchOS
watchOSApplicationExtension
tvOS
tvOSApplicationExtension
swift

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。